Kitava is a Melanesian island that has maintained an almost entirely traditional, non-industrial diet until very recently. It was the subject of a study by Dr. Staffan Lindeberg and colleagues, which I have written about many times, in which they demonstrated that Kitavans have a very low (undetectable) rate of heart attack, stroke, diabetes and overweight. Dr. Lindeberg described their diet as consisting mostly of yam, sweet potato, taro, cassava, coconut, fruit, fish and vegetables. Over the seven days that Dr. Lindeberg measured food intake, they ate 69% of their calories as carbohydrate, 21% as fat (mostly from coconut) and 10% as protein.
I recently received an e-mail from a Kitavan by the name of Job Daniel. He's working at the Papua New Guinea Institute of Medical Research in Madang, studying the social and economic impacts of malaria and related health issues in Papua New Guinea. He recalls many details of Dr. Lindeberg's visit to Kitava, which Dr. Lindeberg has confirmed are correct. Job generously offered to answer some of my questions about the traditional Kitavan diet. My questions are in bold, and his responses are below.
How many meals a day do Kitavans eat?
People on the island eat mostly two meals a day. But nowadays, breakfast is mainly comprised of tubers (yam and sweet potato and greens all cooked in coconut cream and salt) and dinner is the same with the inclusion of fish as protein most often. In between these two meals, lunch is seen as a light refreshment with fruits or young coconut only to mention these two popular ones. In between the morning and the evening, we mostly eat fruits as snack or lunch. Generally speaking, there are only two main meals per day, i.e breakfast and dinner.
Do Kitavans eat any fermented food?
There are fermented fruits and nuts like you've said for breadfruit, nuts, yams and not forgetting fish. We ferment them by using the traditional method of drying them over the fire for months. And this fermented foods last for almost one to two years without getting stale or spoiled. Food preservation is a skill inherited from our great grand fathers taking into consideration the island's location and availability of food. Foods such as bread fruit and fish are fermented and preserved to serve as substitutes to fresh food in times of trouble or shortage. Otherwise, they're eaten along the way.
Is this really fermentation or simply drying?
To your query about the fermentation methods we use, apart from drying food over the fire, we also use this method like the Hawaiians do with taro [poi- SJG]. For our case we bury a special kind of fruit collected from the tree and buried in the ground to ripen, which takes about 2 - 3 days. I don't really know the English name, but we call it 'Natu' in vernecular. There's also a certain nut when it falls from the tree, women collect them and peel off the rotten skin, then mumu [earth oven- SJG] them in the ground covered with leaves to protect them from burning from the extreme heat of the fire, both from the open fire on top and hot stones underneath. After a day, the nuts are removed from the mumu and loaded into very big baskets which are then shifted to the sea for fermentation. This takes a week (minimum) to ferment or be ready for consumption at last. After the fermentation period is over, i.e one week some days or two
weeks to be exact, then the nuts are finally ready for eating. The length of time it takes before the nuts are no longer edible is roughly one week.
What parts of the fish are eaten?
As islanders, we eat almost every creature and body part of a sea creature. Especially fish eggs, it is one of the favorites of children. They always prefer it burnt on the fire and consumed greedily. Every part of the fish is eaten except for the feces, gall bladder, bones and the scales.
Is food shortage really rare on Kitava?
Generally speaking it is rare. BUT sometimes we run out of food only if there is a drought and the sea is useless. Otherwise, we tend to use the preserved or fermented foods on the dryer in the kitchen. As you would understand, we have seasons and they affect the type and availability of food on the island. In the beginning of the year, we eat sweet potato, cassava and mostly tuna for protein. During mid year, before yam comes in to replace sweet potato and cassava, taro is then ready for harvest. And then yams are ready for harvesting so the food supply is continued on. OK when yams are harvested, some are eaten, some are stored away for reserve and seedlings. In this way, we don't run out food towards the end of the year before sweet potato would be ready for harvest. So as you can see, the food supply on the island is somewhat planned by our ancestral economists where it continues throughout the year without stopping.
Do Kitavans traditionally eat pork, and if so, how often?
We do eat pork but not that often because pork meat is chiefly regarded important on the island. We only eat pork on special occasions so I'd rather say that pork is only eaten occasionally. In most cases in the middle of the year when the yams are harvested (yam harvest celebrations and towards the end of the year for certain rites and activities). Otherwise the everyday meal is always topped with fish.
How long are infants breast fed on Kitava?
Women breast feed for a minimum of 2 years. But breast feeding is again determined by the size and health situation of the baby. If the baby is looking healthy and big, it is most likely that this baby would be adopted temporarily by someone else so as to be removed from breast milk after two years of age minimum. Child care nowadays is paramount as people start to realize the importance of health and hygiene in general. But Kitavans are well known in that part of the country for their hygiene practices. They also got the provincial and district awards for a 'clean community' in early 90s and right now, they still maintain their hygiene level and awareness.
Are there any other foods that are commonly eaten on Kitava that I might not be aware of?
Bananas, pineapple, corn and watermelons. For watermelon and corn, they are plentiful especially at this time of the year.
Thanks for your help, Job! I know many people will appreciate reading these responses.
Showing posts with label Kitava. Show all posts
Showing posts with label Kitava. Show all posts
Sunday, December 5, 2010
Wednesday, August 18, 2010
Tropical Plant Fats: Coconut Oil, Part I
Traditional Uses for Coconut
Coconut palms are used for a variety of purposes throughout the tropics. Here are a few quotes from the book Polynesia in Early Historic Times:
Coconut fat is roughly 90 percent saturated, making it one of the most highly saturated fats on the planet. For this reason, it has been the subject of grave pronouncements by health authorities over the course of the last half century, resulting in its near elimination from the industrial food system. If the hypothesis that saturated fat causes heart disease and other health problems is correct, eating coconut oil regularly should tuck us in for a very long nap.
Coconut Eaters
As the Polynesians spread throughout the Eastern Pacific islands, they encountered shallow coral atolls that were not able to sustain their traditional starchy staples, taro, yams and breadfruit. Due to its extreme tolerance for poor, salty soils, the coconut palm was nearly the only food crop that would grow on these islands*. Therefore, their inhabitants lived almost exclusively on coconut and seafood for hundreds of years.
One group of islands that falls into this category is Tokelau, which fortunately for us was the subject of a major epidemiological study that spanned the years 1968 to 1982: the Tokelau Island Migrant Study (1). By this time, Tokelauans had managed to grow some starchy foods such as taro and breadfruit (introduced in the 20th century by Europeans), as well as obtaining some white flour and sugar, but their calories still came predominantly from coconut.
Over the time period in question, Tokelauans obtained roughly half their calories from coconut, placing them among the most extreme consumers of saturated fat in the world. Not only was their blood cholesterol lower than the average Westerner, but their hypertension rate was low, and physicians found no trace of previous heart attacks by ECG (age-adjusted rates: 0.0% in Tokelau vs 3.5% in Tecumseh USA). Migrating to New Zealand and cutting saturated fat intake in half was associated with a rise in ECG signs of heart attack (1.0% age-adjusted) (2, 3).
Diabetes was low in men and average in women by modern Western standards, but increased significantly upon migration to New Zealand and reduction of coconut intake (4). Non-migrant Tokelauans gained body fat at a slower rate than migrants, despite higher physical activity in the latter (5). Together, this evidence seriously challenges the idea that coconut is unhealthy.
The Kitavans also eat an amount of coconut fat that would make Dr. Ancel Keys blush. Dr. Staffan Lindeberg found that they got 21% of their 2,200 calories per day from fat, nearly all of which came from coconut. They were getting 17% of their calories from saturated fat; 55% more than the average American. Dr. Lindeberg's detailed series of studies found no trace of coronary heart disease or stroke, nor any obesity, diabetes or senile dementia even in the very old (6, 7).
Of course, the Tokelauans, Kitavans and other traditional cultures were not eating coconut in the form of refined, hydrogenated coconut oil cake icing. That distinction will be important when I discuss what the biomedical literature has to say in the next post.
* Most also had pandanus palms, which are also tolerant of poor soils and whose fruit provided a small amount of starch and sugar.
Coconut palms are used for a variety of purposes throughout the tropics. Here are a few quotes from the book Polynesia in Early Historic Times:
Most palms begin to produce nuts about five years after germination and continue to yield them for forty to sixty years at a continuous (i.e., nonseasonal) rate, producing about fifty nuts a year. The immature nut contains a tangy liquid that in time transforms into a layer of hard, white flesh on the inner surface of the shell and, somewhat later, a spongy mass of embryo in the nut's cavity. The liquid of the immature nut was often drunk, and the spongy embryo of the mature nut often eaten, raw or cooked, but most nuts used for food were harvested after the meat had been deposited and before the embryo had begun to form...Mainstream Ire
After the nut had been split, the most common method of extracting its hardened flesh was by scraping it out of the shell with a saw-toothed tool of wood, shell, or stone, usually lashed to a three-footed stand. The shredded meat was then eaten either raw or mixed with some starchy food and then cooked, or had its oily cream extracted, by some form of squeezing, for cooking with other foods or for cosmetic or medical uses...
Those Polynesians fortunate enough to have coconut palms utilized their components not only for drink and food-- in some places the most important, indeed life-supporting food-- but also for building-frames, thatch, screens, caulking material, containers, matting, cordage, weapons, armor, cosmetics, medicine, etc.
Coconut fat is roughly 90 percent saturated, making it one of the most highly saturated fats on the planet. For this reason, it has been the subject of grave pronouncements by health authorities over the course of the last half century, resulting in its near elimination from the industrial food system. If the hypothesis that saturated fat causes heart disease and other health problems is correct, eating coconut oil regularly should tuck us in for a very long nap.
Coconut Eaters
As the Polynesians spread throughout the Eastern Pacific islands, they encountered shallow coral atolls that were not able to sustain their traditional starchy staples, taro, yams and breadfruit. Due to its extreme tolerance for poor, salty soils, the coconut palm was nearly the only food crop that would grow on these islands*. Therefore, their inhabitants lived almost exclusively on coconut and seafood for hundreds of years.
One group of islands that falls into this category is Tokelau, which fortunately for us was the subject of a major epidemiological study that spanned the years 1968 to 1982: the Tokelau Island Migrant Study (1). By this time, Tokelauans had managed to grow some starchy foods such as taro and breadfruit (introduced in the 20th century by Europeans), as well as obtaining some white flour and sugar, but their calories still came predominantly from coconut.
Over the time period in question, Tokelauans obtained roughly half their calories from coconut, placing them among the most extreme consumers of saturated fat in the world. Not only was their blood cholesterol lower than the average Westerner, but their hypertension rate was low, and physicians found no trace of previous heart attacks by ECG (age-adjusted rates: 0.0% in Tokelau vs 3.5% in Tecumseh USA). Migrating to New Zealand and cutting saturated fat intake in half was associated with a rise in ECG signs of heart attack (1.0% age-adjusted) (2, 3).
Diabetes was low in men and average in women by modern Western standards, but increased significantly upon migration to New Zealand and reduction of coconut intake (4). Non-migrant Tokelauans gained body fat at a slower rate than migrants, despite higher physical activity in the latter (5). Together, this evidence seriously challenges the idea that coconut is unhealthy.
The Kitavans also eat an amount of coconut fat that would make Dr. Ancel Keys blush. Dr. Staffan Lindeberg found that they got 21% of their 2,200 calories per day from fat, nearly all of which came from coconut. They were getting 17% of their calories from saturated fat; 55% more than the average American. Dr. Lindeberg's detailed series of studies found no trace of coronary heart disease or stroke, nor any obesity, diabetes or senile dementia even in the very old (6, 7).
Of course, the Tokelauans, Kitavans and other traditional cultures were not eating coconut in the form of refined, hydrogenated coconut oil cake icing. That distinction will be important when I discuss what the biomedical literature has to say in the next post.
* Most also had pandanus palms, which are also tolerant of poor soils and whose fruit provided a small amount of starch and sugar.
Thursday, August 21, 2008
Kitava: Wrapping it Up
There's a lot to be learned from the Kitava study. Kitavans eat a diet of root vegetables, coconut, fruit, vegetables and fish and have undetectable levels of cardiovascular disease (CVD), stroke and overweight. Despite smoking like chimneys. 69% of their calories come from carbohydrate, 21% from fat and 10% from protein. This is essentially a carbohydrate-heavy version of what our paleolithic ancestors ate. They also get lots of sunshine and have a moderately high activity level.
The first thing we can say is that a high intake of carbohydrate is not enough, by itself, to cause overweight or the diseases of civilization. It's also not enough to cause insulin resistance. I sent an e-mail to Dr. Lindeberg asking if his group had measured Kitavans' glucose tolerance. He told me they had not. However, I can only guess they had good glucose control since they suffered from none of the complications of unmanaged diabetes.
The Kitavan diet is low in fat, but most of the fat they eat is saturated because it comes from coconuts. Compared to Americans and Swedes, they have a high intake of saturated fat. So much for the theory that saturated fat causes CVD... They also have a relatively high intake of fish fat, at 4g per day. This gives them a high ratio of omega-3 to omega-6 fatty acids, with plenty of DHA and EPA.
Their blood lipid profile is not what a mainstream cardiologist would expect. In fact, it's "worse" than the Swedish profile in many ways, despite the fact that Swedes are highly prone to CVD. This suggests that blood lipids are not causing CVD, but are simply markers of diet and lifestyle factors. That's very easy for me to swallow because it never made sense to me that our livers would try to kill us by secreting triglycerides and witholding HDL. The blood lipid profile that associates best with CVD and metabolic syndrome in the West (but has no relation to them on Kitava) is one that's consistent with a high carbohydrate intake. Where does carbohydrate come from in the West? Grains and sugar maybe?
Kitavans also have very low serum leptin. This may be a keystone to their leanness and health. It suggests that their diet is not interfering with the body's metabolic feedback loops that maintain leanness.
The Kitavan diet is one path to vibrant health. Like many other non-industrial groups, Kitavans eat whole, natural foods that are broadly consistent with what our hunter-gatherer ancestors would have eaten. It amazes me that as humans, we can live well on diets that range from complete carnivory to plant-rich omnivory. We are possibly the most adaptable species on the planet.
The ideal diet for humans includes a lot of possibilities. I believe the focus on macronutrients is misguided. There are examples of cultures that were/are healthy eating high-fat diets, high-carbohydrate diets and everything in between. What they do not eat is processed grains, particularly wheat, refined sugar, industrially processed vegetable oils and other modern foods. I believe these are unhealthy, and this is visible in the trail of destruction they have left around the globe. Its traces can be found in the Pacific islands, where close genetic relatives of the Kitavans have become morbidly obese and unhealthy on a processed-food diet.
One last caveat. I do still believe in the efficacy of low-carbohydrate diets for weight loss and health. The Western diet and lifestyle can damage the metabolism severely, particularly glucose metabolism. It seems to be somewhat reversible, but it depends on the extent of the damage and the individual. People with a history of overweight or poor glucose control should be careful with carbohydrate. It's possible that some people will not be able to handle normal amounts of carbohydrate in any form. Be aware of what your body is telling you.
The first thing we can say is that a high intake of carbohydrate is not enough, by itself, to cause overweight or the diseases of civilization. It's also not enough to cause insulin resistance. I sent an e-mail to Dr. Lindeberg asking if his group had measured Kitavans' glucose tolerance. He told me they had not. However, I can only guess they had good glucose control since they suffered from none of the complications of unmanaged diabetes.
The Kitavan diet is low in fat, but most of the fat they eat is saturated because it comes from coconuts. Compared to Americans and Swedes, they have a high intake of saturated fat. So much for the theory that saturated fat causes CVD... They also have a relatively high intake of fish fat, at 4g per day. This gives them a high ratio of omega-3 to omega-6 fatty acids, with plenty of DHA and EPA.
Their blood lipid profile is not what a mainstream cardiologist would expect. In fact, it's "worse" than the Swedish profile in many ways, despite the fact that Swedes are highly prone to CVD. This suggests that blood lipids are not causing CVD, but are simply markers of diet and lifestyle factors. That's very easy for me to swallow because it never made sense to me that our livers would try to kill us by secreting triglycerides and witholding HDL. The blood lipid profile that associates best with CVD and metabolic syndrome in the West (but has no relation to them on Kitava) is one that's consistent with a high carbohydrate intake. Where does carbohydrate come from in the West? Grains and sugar maybe?
Kitavans also have very low serum leptin. This may be a keystone to their leanness and health. It suggests that their diet is not interfering with the body's metabolic feedback loops that maintain leanness.
The Kitavan diet is one path to vibrant health. Like many other non-industrial groups, Kitavans eat whole, natural foods that are broadly consistent with what our hunter-gatherer ancestors would have eaten. It amazes me that as humans, we can live well on diets that range from complete carnivory to plant-rich omnivory. We are possibly the most adaptable species on the planet.
The ideal diet for humans includes a lot of possibilities. I believe the focus on macronutrients is misguided. There are examples of cultures that were/are healthy eating high-fat diets, high-carbohydrate diets and everything in between. What they do not eat is processed grains, particularly wheat, refined sugar, industrially processed vegetable oils and other modern foods. I believe these are unhealthy, and this is visible in the trail of destruction they have left around the globe. Its traces can be found in the Pacific islands, where close genetic relatives of the Kitavans have become morbidly obese and unhealthy on a processed-food diet.
One last caveat. I do still believe in the efficacy of low-carbohydrate diets for weight loss and health. The Western diet and lifestyle can damage the metabolism severely, particularly glucose metabolism. It seems to be somewhat reversible, but it depends on the extent of the damage and the individual. People with a history of overweight or poor glucose control should be careful with carbohydrate. It's possible that some people will not be able to handle normal amounts of carbohydrate in any form. Be aware of what your body is telling you.
Wednesday, August 20, 2008
Cardiovascular Risk Factors on Kitava, Part IV: Leptin
Leptin is a hormone that is a central player in the process of weight gain and chronic disease. Its existence had been predicted for decades, but it was not identified until 1994. Although less well known than insulin, its effects on nutrient disposal, metabolic rate and feeding behaviors place it on the same level of importance.
Caloric intake and expenditure vary from day to day and week to week in humans, yet most people maintain a relatively stable weight without consciously adjusting food intake. For example, I become hungry after a long fast, whereas I won't be very hungry if I've stuffed myself for two meals in a row. This suggests a homeostatic mechanism, or feedback loop, which keeps weight in the body's preferred range. Leptin is the major feedback signal.
Here's how it works. Leptin is secreted by adipose (fat) tissue, and its blood levels are proportional to fat mass. The more fat, the more leptin. It acts in the brain to increase the metabolic rate, decrease eating behaviors, and inhibit the deposition of fat. Thus, if fat mass increases, hunger diminishes and the body tries to burn calories to regain its preferred equilibrium.
The next logical question is "how could anyone become obese if this feedback loop inhibits energy storage in response to fat gain?" The answer is a problem called leptin resistance. In people who are obese, the brain no longer responds to the leptin signal. In fact, the brain believes leptin levels are low, implying stored energy is low, so it thinks it's starving. This explains the low metabolic rate, increased tendency for fat storage and hyperphagia (increased eating) seen in many obese people. Leptin resistance has reset the body's preferred weight 'set-point' to a higher level.
Incidentally, some reaserchers have claimed that obese people gain fat because they don't fidget as much as others (a variation on the "obesity is caused by sloth" theory). This is based on the observation that thin people fidget more than overweight people. Leptin also influences activity levels, so I would argue that obese people fidget less than thin people due to their leptin resistance. In other words, they fidget less because they're fat, rather than the other way around.
The problem of leptin resistance is well illustrated by a rat model called the Zucker fatty strain. The Zucker rat has a mutation in the leptin receptor gene, making its brain unresponsive to leptin signals. The rat's fat tissue pumps out leptin, but its brain is deaf to it. This is basically a model of severe leptin resistance, the same thing we see in obese humans. What happens to these rats? They become hyperphagic, hypometabolic, obese, develop insulin resistance, impaired glucose tolerance, dyslipidemia, diabetes, and cardiovascular disease. Basically, severe metabolic syndrome.
This shows that leptin resistance is sufficient to cause many of the common metabolic problems that plague modern societies. In humans, it's a little known fact that leptin resistance precedes the development of obesity, insulin resistance, and impaired glucose tolerance! Furthermore, humans with leptin receptor mutations or impaired leptin production become hyperphagic and severely obese. This puts leptin at the top of my list of suspects.
So here we have the Kitavans, who are thin and healthy. How's their leptin? Incredibly low. Even in young individuals, Kitavan leptin levels average less than half of Swedish levels. Beyond age 60, Kitavans have 1/4 the leptin level of Swedish people. The difference is so great, the standard deviations don't even overlap.
This isn't surprising, since leptin levels track with fat mass and the Kitavans are very lean (average male BMI = 20, female BMI = 18). Now we are faced with a chicken and egg question. Are Kitavans thin because they're leptin-sensitive, or are they leptin-sensitive because they're thin?
There's no way to answer this question conclusively using the data I'm familiar with. However, in mice and humans, leptin resistance by itself can initiate a spectrum of metabolic problems very reminiscent of what we see so frequently in modern societies. This leads me to believe that there's something about the modern lifestyle that causes leptin resistance. As usual, my microscope is pointed directly at wheat. Its lectins are capable of binding to and desensitizing the leptin and insulin receptors in vitro, as I wrote about before. Staffan Lindeberg proposed that grain lectins could be responsible for leptin resistance here. This is one of many possible mechanisms by which wheat could wreak metabolic damage, particularly in its industrially processed form.
Caloric intake and expenditure vary from day to day and week to week in humans, yet most people maintain a relatively stable weight without consciously adjusting food intake. For example, I become hungry after a long fast, whereas I won't be very hungry if I've stuffed myself for two meals in a row. This suggests a homeostatic mechanism, or feedback loop, which keeps weight in the body's preferred range. Leptin is the major feedback signal.
Here's how it works. Leptin is secreted by adipose (fat) tissue, and its blood levels are proportional to fat mass. The more fat, the more leptin. It acts in the brain to increase the metabolic rate, decrease eating behaviors, and inhibit the deposition of fat. Thus, if fat mass increases, hunger diminishes and the body tries to burn calories to regain its preferred equilibrium.
The next logical question is "how could anyone become obese if this feedback loop inhibits energy storage in response to fat gain?" The answer is a problem called leptin resistance. In people who are obese, the brain no longer responds to the leptin signal. In fact, the brain believes leptin levels are low, implying stored energy is low, so it thinks it's starving. This explains the low metabolic rate, increased tendency for fat storage and hyperphagia (increased eating) seen in many obese people. Leptin resistance has reset the body's preferred weight 'set-point' to a higher level.
Incidentally, some reaserchers have claimed that obese people gain fat because they don't fidget as much as others (a variation on the "obesity is caused by sloth" theory). This is based on the observation that thin people fidget more than overweight people. Leptin also influences activity levels, so I would argue that obese people fidget less than thin people due to their leptin resistance. In other words, they fidget less because they're fat, rather than the other way around.
The problem of leptin resistance is well illustrated by a rat model called the Zucker fatty strain. The Zucker rat has a mutation in the leptin receptor gene, making its brain unresponsive to leptin signals. The rat's fat tissue pumps out leptin, but its brain is deaf to it. This is basically a model of severe leptin resistance, the same thing we see in obese humans. What happens to these rats? They become hyperphagic, hypometabolic, obese, develop insulin resistance, impaired glucose tolerance, dyslipidemia, diabetes, and cardiovascular disease. Basically, severe metabolic syndrome.
This shows that leptin resistance is sufficient to cause many of the common metabolic problems that plague modern societies. In humans, it's a little known fact that leptin resistance precedes the development of obesity, insulin resistance, and impaired glucose tolerance! Furthermore, humans with leptin receptor mutations or impaired leptin production become hyperphagic and severely obese. This puts leptin at the top of my list of suspects.
So here we have the Kitavans, who are thin and healthy. How's their leptin? Incredibly low. Even in young individuals, Kitavan leptin levels average less than half of Swedish levels. Beyond age 60, Kitavans have 1/4 the leptin level of Swedish people. The difference is so great, the standard deviations don't even overlap.
This isn't surprising, since leptin levels track with fat mass and the Kitavans are very lean (average male BMI = 20, female BMI = 18). Now we are faced with a chicken and egg question. Are Kitavans thin because they're leptin-sensitive, or are they leptin-sensitive because they're thin?
There's no way to answer this question conclusively using the data I'm familiar with. However, in mice and humans, leptin resistance by itself can initiate a spectrum of metabolic problems very reminiscent of what we see so frequently in modern societies. This leads me to believe that there's something about the modern lifestyle that causes leptin resistance. As usual, my microscope is pointed directly at wheat. Its lectins are capable of binding to and desensitizing the leptin and insulin receptors in vitro, as I wrote about before. Staffan Lindeberg proposed that grain lectins could be responsible for leptin resistance here. This is one of many possible mechanisms by which wheat could wreak metabolic damage, particularly in its industrially processed form.
Sunday, August 17, 2008
Cardiovascular Risk Factors on Kitava, Part III: Insulin
The Kitava study continues to get more and more interesting in later publications. Dr. Lindeberg and his colleagues continued exploring disease markers in the Kitavans, perhaps because their blood lipid findings were not consistent with what one would expect to find in a modern Western population with a low prevalence of CVD.
In their next study, the researchers examined Kitavans' insulin levels compared to Swedish controls. This paper is short but very sweet. Young Kitavan men and women have a fasting serum insulin level considerably lower than their Swedish counterparts (KM 3.9 IU/mL; SM 5.7; KW 3.5; SW 6.2). Kitavan insulin is relatively stable with age, whereas Swedish insulin increases. In the 60-74 year old group, Kitavans have approximately half the fasting serum insulin of Swedes. One thing to keep in mind is that these are average numbers. There is some overlap between the Kitavan and Swedish numbers, with a few Kitavans above the Swedish mean.
In figure 2, they address the possibility that exercise is the reason for Kitavans' low insulin levels. Kitavans have an activity level comparable to a moderately active Swedish person. They divided the Swedes into three categories: low, medium, and high amounts of physical activity at work. The people in the "low" category had the highest insulin, followed by the "high" group and then the "medium" group. The differences were small, however, and Kitavans had far lower serum insulin, on average, than any of the three Swedish groups. These data show that exercise can not explain Kitavans' low insulin levels.
The researchers also found that they could accurately predict average Swedish and Kitavan insulin levels using an equation that factored in age, BMI and waist circumference. This shows that there is a strong correlation between body composition and insulin levels, which applies across cultures.
Now it's time to take a step back and do some interpreting. First of all, this paper is consistent with the idea (but does not prove) that elevated insulin is a central element of overweight, vascular disease and possibly the other diseases of civilization. While we saw previously that mainstream blood lipid markers do not correlate well with CVD or stroke on Kitava, insulin has withstood the cross-cultural test.
In my opinion, the most important finding in this paper is that a high-carbohydrate diet does not necessarily lead to elevated fasting insulin. This is why I think the statement "carbohydrate drives insulin drives fat" is an oversimplification. What drives fat accumulation is chronically high insulin (hyperinsulinemia), which the Kitavans do not have. With a properly-functioning pancreas and insulin-sensitive tissues (which many people in industrial societies do not have), a healthy person can eat a high-carbohydrate meal and keep blood glucose under control. Insulin definitely spikes, but it's temporary. The rest of the day, insulin is at basal levels. The Kitavans show that insulin spikes per se do not cause hyperinsulinemia.
So this leads to the Big Question: what causes hyperinsulinemia?? The best I can give you is informed speculation. Who has hyperinsulinemia? Industrial populations, especially the U.S. and native populations that have adopted Western foods. Who doesn't? Non-industrial populations that have not been affected by Western food habits, including the traditional Inuit, the Kuna, the traditional Masai and the Kitavans.
We can safely rule out that total fat, saturated fat and carbohydrate cause hyperinsulinemia, based on data from the Inuit, the Masai and the Kitavans, respectively. We can also safely rule out that there's some specific food that protects these populations, since they eat completely different things. Exercise is also not a compelling explanation, based on the data above and others. What does that leave us with? Western food habits. In my opinion, the trail of metabolic destruction that has followed Westerners throughout the world is probably due in large part to wheat and refined sugar.
I'm not the first person to come up with this idea, far from it. The idea that specific types of carbohydrate foods, rather than carbohydrate in general, are responsible for the diseases of civilization, has been around for at least a century. It was an inescapable conclusion in the time of Weston Price, when anthropologists and field physicians could observe the transitions of native people to Western diets all over the world. This information has gradually faded from our collective consciousness as native cultures have become increasingly rare. The Kitava study is a helpful modern-day reminder.
In their next study, the researchers examined Kitavans' insulin levels compared to Swedish controls. This paper is short but very sweet. Young Kitavan men and women have a fasting serum insulin level considerably lower than their Swedish counterparts (KM 3.9 IU/mL; SM 5.7; KW 3.5; SW 6.2). Kitavan insulin is relatively stable with age, whereas Swedish insulin increases. In the 60-74 year old group, Kitavans have approximately half the fasting serum insulin of Swedes. One thing to keep in mind is that these are average numbers. There is some overlap between the Kitavan and Swedish numbers, with a few Kitavans above the Swedish mean.
In figure 2, they address the possibility that exercise is the reason for Kitavans' low insulin levels. Kitavans have an activity level comparable to a moderately active Swedish person. They divided the Swedes into three categories: low, medium, and high amounts of physical activity at work. The people in the "low" category had the highest insulin, followed by the "high" group and then the "medium" group. The differences were small, however, and Kitavans had far lower serum insulin, on average, than any of the three Swedish groups. These data show that exercise can not explain Kitavans' low insulin levels.
The researchers also found that they could accurately predict average Swedish and Kitavan insulin levels using an equation that factored in age, BMI and waist circumference. This shows that there is a strong correlation between body composition and insulin levels, which applies across cultures.
Now it's time to take a step back and do some interpreting. First of all, this paper is consistent with the idea (but does not prove) that elevated insulin is a central element of overweight, vascular disease and possibly the other diseases of civilization. While we saw previously that mainstream blood lipid markers do not correlate well with CVD or stroke on Kitava, insulin has withstood the cross-cultural test.
In my opinion, the most important finding in this paper is that a high-carbohydrate diet does not necessarily lead to elevated fasting insulin. This is why I think the statement "carbohydrate drives insulin drives fat" is an oversimplification. What drives fat accumulation is chronically high insulin (hyperinsulinemia), which the Kitavans do not have. With a properly-functioning pancreas and insulin-sensitive tissues (which many people in industrial societies do not have), a healthy person can eat a high-carbohydrate meal and keep blood glucose under control. Insulin definitely spikes, but it's temporary. The rest of the day, insulin is at basal levels. The Kitavans show that insulin spikes per se do not cause hyperinsulinemia.
So this leads to the Big Question: what causes hyperinsulinemia?? The best I can give you is informed speculation. Who has hyperinsulinemia? Industrial populations, especially the U.S. and native populations that have adopted Western foods. Who doesn't? Non-industrial populations that have not been affected by Western food habits, including the traditional Inuit, the Kuna, the traditional Masai and the Kitavans.
We can safely rule out that total fat, saturated fat and carbohydrate cause hyperinsulinemia, based on data from the Inuit, the Masai and the Kitavans, respectively. We can also safely rule out that there's some specific food that protects these populations, since they eat completely different things. Exercise is also not a compelling explanation, based on the data above and others. What does that leave us with? Western food habits. In my opinion, the trail of metabolic destruction that has followed Westerners throughout the world is probably due in large part to wheat and refined sugar.
I'm not the first person to come up with this idea, far from it. The idea that specific types of carbohydrate foods, rather than carbohydrate in general, are responsible for the diseases of civilization, has been around for at least a century. It was an inescapable conclusion in the time of Weston Price, when anthropologists and field physicians could observe the transitions of native people to Western diets all over the world. This information has gradually faded from our collective consciousness as native cultures have become increasingly rare. The Kitava study is a helpful modern-day reminder.
Friday, August 15, 2008
Cardiovascular Risk Factors on Kitava, Part II: Blood Lipids
The findings in the previous post are all pretty much expected in a population that doesn't get heart disease. However, things started to get interesting when Lindeberg's group measured the Kitavans' serum lipids ("cholesterol"). Kitavan and Swedish total cholesterol is about the same in young men, around 174 mg/dL (4.5 mmol/L). It rises with age in older Swedish men but not Kitavans.
Doctors commonly refer to total cholesterol over 200 mg/dL (5.2 mmol/L) as "high", so Kitavan men are in the clear. On the other hand, Kitavan women should be dying of heart disease left and right with their high middle-age cholesterol of 247 mg/dL (6.4 mmol/L)! That's actually higher than the value for Swedish women of the same age, who are far more prone to heart disease than Kitavans.
The fun doesn't stop there. Total cholesterol isn't a good predictor of heart attack risk, but there are better measures. Some of the best predictors in Western populations are low HDL and high triglycerides (these are also markers of the metabolic syndrome). It's well established that HDL goes down on a high-carbohydrate diet, and triglycerides go up. That's exactly what we see in Kitavans. Their HDL is slightly lower than Swedes' at middle and old age, and their triglycerides are higher on average. Judging by these numbers, Kitavans should have cardiovascular disease (CVD) equal to or worse than Swedes, who suffer from a high rate of cardiovascular mortality.
Kitavan smokers had a lower HDL than nonsmokers, yet still did not develop CVD. Smoking is considered one of the most powerful risk factors for cardiovascular disease in Western populations.
I won't discuss LDL much because it's a weak predictor, but in case you're interested, it's lower in Kitavan males than Swedish males. It's about the same in Kitavan and Swedish females until old age, when Swedish LDL goes up.
These data seriously challenge the theory that certain patterns of blood lipids cause CVD. Kitavans, particularly the women, have a blood lipid profile that should have them clutching their chests, yet they remain healthy.
I have a theory of the relationship between blood lipids and CVD that can explain these data. I believe that blood lipids, rather than causing CVD, simply reflect diet composition and other lifestyle factors. Both on Kitava and in the West, low HDL and elevated triglycerides imply a high carbohydrate intake. Low-carbohydrate diets consistently raise HDL and lower triglycerides. On Kitava, carbohydrate comes mostly from root crops. In the West, it comes mostly from processed grains (typically wheat) and sugar. So the blood lipid pattern that associates best with CVD and the metabolic syndrome in the West is simply a marker of grain and sugar intake.
Doctors commonly refer to total cholesterol over 200 mg/dL (5.2 mmol/L) as "high", so Kitavan men are in the clear. On the other hand, Kitavan women should be dying of heart disease left and right with their high middle-age cholesterol of 247 mg/dL (6.4 mmol/L)! That's actually higher than the value for Swedish women of the same age, who are far more prone to heart disease than Kitavans.
The fun doesn't stop there. Total cholesterol isn't a good predictor of heart attack risk, but there are better measures. Some of the best predictors in Western populations are low HDL and high triglycerides (these are also markers of the metabolic syndrome). It's well established that HDL goes down on a high-carbohydrate diet, and triglycerides go up. That's exactly what we see in Kitavans. Their HDL is slightly lower than Swedes' at middle and old age, and their triglycerides are higher on average. Judging by these numbers, Kitavans should have cardiovascular disease (CVD) equal to or worse than Swedes, who suffer from a high rate of cardiovascular mortality.
Kitavan smokers had a lower HDL than nonsmokers, yet still did not develop CVD. Smoking is considered one of the most powerful risk factors for cardiovascular disease in Western populations.
I won't discuss LDL much because it's a weak predictor, but in case you're interested, it's lower in Kitavan males than Swedish males. It's about the same in Kitavan and Swedish females until old age, when Swedish LDL goes up.
These data seriously challenge the theory that certain patterns of blood lipids cause CVD. Kitavans, particularly the women, have a blood lipid profile that should have them clutching their chests, yet they remain healthy.
I have a theory of the relationship between blood lipids and CVD that can explain these data. I believe that blood lipids, rather than causing CVD, simply reflect diet composition and other lifestyle factors. Both on Kitava and in the West, low HDL and elevated triglycerides imply a high carbohydrate intake. Low-carbohydrate diets consistently raise HDL and lower triglycerides. On Kitava, carbohydrate comes mostly from root crops. In the West, it comes mostly from processed grains (typically wheat) and sugar. So the blood lipid pattern that associates best with CVD and the metabolic syndrome in the West is simply a marker of grain and sugar intake.
Thursday, August 14, 2008
Cardiovascular Risk Factors on Kitava, Part I: Weight and Blood Pressure
The Kitavans are an isolated population free of cardiovascular disease and stroke, despite the fact that more than three quarters of them smoke cigarettes. They eat a carbohydrate-heavy, whole-foods diet that is uninfluenced by modern food habits and consists mostly of starchy root crops, fruit, vegetables, coconut and fish. Their intake of grains and processed foods is negligible.
Naturally, when Dr. Lindeberg's group discovered that Kitavans don't suffer from heart disease or stroke, they investigated further. In the second paper of the series, they analyzed the Kitavans' "cardiovascular risk factors" that sometimes associate with heart disease in Western populations, such as overweight, hypertension, elevated total cholesterol and other blood lipid markers.
Kitavans are lean. Adult male body mass index (BMI) starts out at 22, and diminishes with age. For comparison, Swedes begin at a BMI of 25 and stay that way. Both populations lose muscle mass with age, so Kitavans are staying lean while Swedes are gaining fat. The average American has a BMI of about 28, which is considered overweight and 2 points away from being obese.
Kitavans also have a low blood pressure that rises modestly with age. This is actually a bit surprising to me, since other non-industrial groups like the Kuna do not experience a rise in blood pressure with age. Compared with Swedes, Kitavans' blood pressure is considerably lower at all ages.
In the next post, I'll discuss the Kitavans' blood lipid numbers ("cholesterol"), which challenge current thinking about heart disease risk factors.
Naturally, when Dr. Lindeberg's group discovered that Kitavans don't suffer from heart disease or stroke, they investigated further. In the second paper of the series, they analyzed the Kitavans' "cardiovascular risk factors" that sometimes associate with heart disease in Western populations, such as overweight, hypertension, elevated total cholesterol and other blood lipid markers.
Kitavans are lean. Adult male body mass index (BMI) starts out at 22, and diminishes with age. For comparison, Swedes begin at a BMI of 25 and stay that way. Both populations lose muscle mass with age, so Kitavans are staying lean while Swedes are gaining fat. The average American has a BMI of about 28, which is considered overweight and 2 points away from being obese.
Kitavans also have a low blood pressure that rises modestly with age. This is actually a bit surprising to me, since other non-industrial groups like the Kuna do not experience a rise in blood pressure with age. Compared with Swedes, Kitavans' blood pressure is considerably lower at all ages.
In the next post, I'll discuss the Kitavans' blood lipid numbers ("cholesterol"), which challenge current thinking about heart disease risk factors.
Wednesday, August 13, 2008
The Kitavans: Wisdom from the Pacific Islands
There are very few cultures left on this planet that have not been affected by modern food habits. There are even fewer that have been studied thoroughly. The island of Kitava in Papua New Guinea is host to one such culture, and its inhabitants have many profound things to teach us about diet and health.
The Kitava study, a series of papers produced primarily by Dr. Staffan Lindeberg and his collaborators, offers a glimpse into the nutrition and health of an ancient society, using modern scientific methods. This study is one of the most complete and useful characterizations of the diet and health of a non-industrial society I have come across. It's also the study that created, and ultimately resolved, my cognitive dissonance over the health effects of carbohydrate.
From the photos I've seen, the Kitavans are beautiful people. They have the broad, attractive faces, smooth skin and excellent teeth typical of healthy non-industrial peoples.
Like the Kuna, Kitavans straddle the line between agricultural and hunter-gatherer lifestyles. They eat a diet primarily composed of tubers (yam, sweet potato, taro and cassava), fruit, vegetables, coconut and fish, in order of calories. This is typical of traditional Pacific island cultures, although the relative amounts differ.
Grains, refined sugar, vegetable oils and other processed foods are virtually nonexistent on Kitava. They get an estimated 69% of their calories from carbohydrate, 21% from fat, 17% from saturated fat and 10% from protein. Most of their fat intake is saturated because it comes from coconuts. They have an omega-6 : omega-3 ratio of approximately 1:2. Average caloric intake is 2,200 calories per day (9,200 kJ). By Western standards, their diet is high in carbohydrate, high in saturated fat, low in total fat, a bit low in protein and high in calories.
Now for a few relevant facts before we really start diving in:
Overall, Kitavans possess a resistance to degenerative diseases that is baffling to industrialized societies. Not only is this typical of non-industrial cultures, I believe it represents the natural state of existence for Homo sapiens. Like all other animals, humans are healthy and robust when occupying their preferred ecological niche. Our niche happens to be a particularly broad one, ranging from complete carnivory to plant-rich omnivory. But it does not include large amounts of grains or modern industrial foods.
In the next few posts, I'll discuss more specific data about the health of the Kitavans, including their body composition, serum lipids, and hormone profile. These data challenge the theory of an "atherogenic lipid profile", the idea that certain blood lipid patterns cause heart disease.
The Kitava study, a series of papers produced primarily by Dr. Staffan Lindeberg and his collaborators, offers a glimpse into the nutrition and health of an ancient society, using modern scientific methods. This study is one of the most complete and useful characterizations of the diet and health of a non-industrial society I have come across. It's also the study that created, and ultimately resolved, my cognitive dissonance over the health effects of carbohydrate.
From the photos I've seen, the Kitavans are beautiful people. They have the broad, attractive faces, smooth skin and excellent teeth typical of healthy non-industrial peoples.
Like the Kuna, Kitavans straddle the line between agricultural and hunter-gatherer lifestyles. They eat a diet primarily composed of tubers (yam, sweet potato, taro and cassava), fruit, vegetables, coconut and fish, in order of calories. This is typical of traditional Pacific island cultures, although the relative amounts differ.
Grains, refined sugar, vegetable oils and other processed foods are virtually nonexistent on Kitava. They get an estimated 69% of their calories from carbohydrate, 21% from fat, 17% from saturated fat and 10% from protein. Most of their fat intake is saturated because it comes from coconuts. They have an omega-6 : omega-3 ratio of approximately 1:2. Average caloric intake is 2,200 calories per day (9,200 kJ). By Western standards, their diet is high in carbohydrate, high in saturated fat, low in total fat, a bit low in protein and high in calories.
Now for a few relevant facts before we really start diving in:
- Kitavans are not particularly active. They have an activity level comparable to a moderately active Swede, the population to which Dr. Lindeberg draws frequent comparisons.
- They have abundant food, and shortage is practically unknown.
- Their good health is probably not related to genetics, since genetically similar groups in the same region are exquisitely sensitive to the ravages of industrial food. Furthermore, the only Kitavan who moved away from the island to live a modern life is also the only fat Kitavan.
- Their life expectancy at birth is estimated at 45 years (includes infant mortality), and life expectancy at age 50 is an additional 25 years. This is remarkable for a culture with limited access to modern medicine.
- Over 75% of Kitavans smoke cigarettes. Even the most isolated societies have their modern vices.
For the whole of PNG, no case of IHD or atherothrombotic stroke has been reported in clinical investigations and autopsy studies among traditionally living Melanesians for more than seven decades, though an increasing number of myocardial infarctions [heart attacks] and angina pectoris in urbanized populations have been reported since the 1960s.Dementia was not found except in in two young Kitavans, who were born handicapped. The elderly remained sharp until death, including one man who reached 100 years of age. Kitavans are also unfamiliar with external cancers, with the exception of one possible case of breast cancer in an elderly woman.
Overall, Kitavans possess a resistance to degenerative diseases that is baffling to industrialized societies. Not only is this typical of non-industrial cultures, I believe it represents the natural state of existence for Homo sapiens. Like all other animals, humans are healthy and robust when occupying their preferred ecological niche. Our niche happens to be a particularly broad one, ranging from complete carnivory to plant-rich omnivory. But it does not include large amounts of grains or modern industrial foods.
In the next few posts, I'll discuss more specific data about the health of the Kitavans, including their body composition, serum lipids, and hormone profile. These data challenge the theory of an "atherogenic lipid profile", the idea that certain blood lipid patterns cause heart disease.
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