A report came out recently showing that melanoma incidence has increased dramatically in the US since 1973, particularly among women. The authors suggested the rise could be due to increasing sun exposure, which I am highly skeptical of. The data he cites to support that idea are quite weak. I think the prevalence of vitamin D deficiency in this country suggests otherwise.
Melanoma is the most deadly form of skin cancer, and the only type that is commonly life-threatening. Its link to sun exposure is tenuous at best. For example, it often occurs on the least sun-exposed parts of the body, and its incidence is lower in outdoor workers.
What is the solution to rising melanoma incidence? Sunblock! Slather it on, ladies and gentlemen! No matter that we evolved outdoors! No matter that it may do nothing for melanoma incidence or mortality! No matter that you'll be vitamin D deficient! No matter that it contains known carcinogens! 30+ SPF, the more the better. Don't let one single deadly UV photon through.
The irony of all this is that if you believe the data on vitamin D, avoiding the sun would cause many more cancers than it would prevent, even if all melanoma were due to sun exposure.
Monday, July 14, 2008
Sunday, July 13, 2008
Fish Oil and Asthma Weirdness
I read an interesting study today on fish oil and asthma. It's the result of a randomized controlled trial, the kind that can actually tell us about cause and effect.In 1990, researchers assembled a group of 533 pregnant women and divided them into three groups. One group received 4g/day fish oil in capsules, one group got 4g/day of olive oil in capsules, and the third group got no oil. They were told to take the capsules from gestational week 30 until delivery. The 16 year-old children of women who took fish oil capsules during pregnancy had a 63% lower rate of asthma than the olive oil group, and an 87% lower rate of allergic asthma. Pretty straightforward.
Now for the weirdness. The no oil group actually did better than the other two groups, with a 71% lower asthma rate than the olive oil group, and no cases of allergic asthma whatsoever! The result was not statistically different from the fish oil group however. So we have just gone from a result that suggests fish oil is protective, to one that suggests fish oil is neutral and olive oil is detrimental!
The result is really hard to believe, especially since Mediterranean countries with high olive oil intakes don't have elevated rates of asthma. It was also hard for the authors to believe, so they invoked a concept called "contamination bias". In this case, what that means is that the no oil group may have been eating more fish than the olive oil group.
It could have happened because they had been informed of the study's hypothesis (this was required by the Danish Scientific Ethical Committee System). They knew they weren't getting fish oil, they knew there was preliminary evidence that fish oil protects against preterm birth and heart disease (in the Inuit, incidentally), so the authors speculate that they went out and started eating fish. This didn't happen in the olive oil group because according to a questionnaire, half of them thought they were getting fish oil already!
I will say, in favor of this hypothesis, that the no oil group looks remarkably like the fish oil group in terms of the rate and age of onset of asthma. I think the result needs to be replicated before we can really say what happened. It's unfortunate, because it was a large, well-designed study. In the meantime, keep on eating fish.
Thanks to snowriderguy for the CC photo
Friday, July 11, 2008
How to Dress to Minimize a Large Bust
Here's a nice video by Katie Stiles on how to dress to minimize and flatter a very large bust. She shows us five before and after outfits and tops.Via Before and After TV
Thursday, July 10, 2008
Grains and Human Evolution
You've heard me say that I believe grains aren't an ideal food for humans. Part of the reason rests on the assertion that we have not been eating grains for long enough to have adapted to them. In this post, I'll go over what I know about the human diet before and after agriculture, and the timeline of our shift to a grain-based diet. I'm not an archaeologist so I won't claim that all these numbers are exact, but I think they are close enough to make my point.
As hunter-gatherers, we ate some combination of the following: land mammals (including organs, fat and marrow), cooked tubers, seafood (fish, mammals, shellfish, seaweed), eggs, nuts, fruit, honey, "vegetables" (stems, leaves, etc.), mushrooms, assorted land animals, birds and insects. The proportion of each food varied widely between groups and even seasons. This is pretty much what we've been living on since we evolved as a species, and even before, for a total of 1.5 million years or so (this number is controversial but is supported by multiple lines of evidence). There are minor exceptions, including the use of wild grains in a few areas, but for the most part, that's it.
The first evidence of a calorically important domesticated crop I'm aware of was about 11,500 years ago in the fertile crescent. They were cultivating an early ancestor of wheat called emmer. Other grains popped up independently in what is now China (rice; ~10,000 years ago), and central America (corn; ~9,000 years ago). That's why people say humans have been eating grains for about 10,000 years.
The story is more complicated than the dates suggest, however. Although wheat had its origin 11,500 years ago, it didn't become widespread in Western Europe for another 4,500 years. So if you're of European descent, your ancestors have been eating grains for roughly 7,000 years. Corn was domesticated 9,000 years ago, but according to the carbon ratios of human teeth, it didn't become a major source of calories until about 1,200 years ago! Many American groups did not adopt a grain-based diet until 100-300 years ago, and in a few cases they still have not. If you are of African descent, your ancestors have been eating grains for 9,000 to 0 years, depending on your heritage. The change to grains was accompanied by a marked decrease in dental health that shows up clearly in the archaeological record.
Practically every plant food contains some kind of toxin, but grains produce a number of nasty ones that humans are not well adapted to. Grains contain a large amount of phytic acid for example, which strongly inhibits the absorption of a number of important minerals. Tubers, which were our main carbohydrate source for about 1.5 million years before agriculture, contain less of it. This may have been a major reason why stature decreased when humans adopted grain-based agriculture. There are a number of toxins that occur in grains but not in tubers, such as certain heat-resistant lectins.
Non-industrial cultures often treated their seeds, including grains, differently than we do today. They used soaking, sprouting and long fermentation to decrease the amount of toxins found in grains, making them more nutritious and digestible. Most grain staples are not treated in this way today, and so we bear the brunt of their toxins even more than our ancestors did.
From an evolutionary standpoint, even 11,500 years is the blink of an eye. Add to that the fact that many people descend from groups that have been eating grains for far less time than that, and you begin to see the problem. There is no doubt that we have begun adapting genetically to grains. All you have to do to understand this is look back at the archaeological record, to see the severe selective pressure (read: disease) that grains placed on its early adopters. But the question is, have we had time to adapt sufficiently to make it a healthy food? I would argue the answer is no.
There are a few genetic adaptations I'm aware of that might pertain to grains: the duplication of the salivary amylase gene, and polymorphisms in the angiotensin-converting enzyme (ACE) and apolipoprotein B genes. Some groups duplicated a gene that secretes the enzyme amylase into the saliva, increasing its production. Amylase breaks down starch, indicating a possible increase in its consumption. The problem is that we were getting starch from tubers before we got it from grains, so it doesn't really argue for either side in my opinion. The ACE and apolipoprotein B genes may be more pertinent, because they relate to blood pressure and LDL cholesterol. Blood pressure and blood cholesterol are both factors that respond well to low-carbohydrate (and thus low-grain) diets, suggesting that the polymorphisms may be a protective adaptation against the cardiovascular effects of grains.
The fact that up to 1% of people of European descent may have full-blown celiac disease attests to the fact that 7,000 years have not been enough time to fully adapt to wheat on a population level. Add to that the fact that nearly half of genetic Europeans carry genes that are associated with celiac, and you can see that we haven't been weeded out thoroughly enough to tolerate wheat, the oldest grain!
Based on my reading, discussions and observations, I believe that rice is the least problematic grain, wheat is the worst, and everything else is somewhere in between. If you want to eat grains, it's best to soak, sprout or ferment them. This activates enzymes that break down most of the toxins. You can soak rice, barley and other grains overnight before cooking them. Sourdough bread is better than normal white bread. Unfermented, unsprouted whole wheat bread may actually be the worst of all.
As hunter-gatherers, we ate some combination of the following: land mammals (including organs, fat and marrow), cooked tubers, seafood (fish, mammals, shellfish, seaweed), eggs, nuts, fruit, honey, "vegetables" (stems, leaves, etc.), mushrooms, assorted land animals, birds and insects. The proportion of each food varied widely between groups and even seasons. This is pretty much what we've been living on since we evolved as a species, and even before, for a total of 1.5 million years or so (this number is controversial but is supported by multiple lines of evidence). There are minor exceptions, including the use of wild grains in a few areas, but for the most part, that's it.
The first evidence of a calorically important domesticated crop I'm aware of was about 11,500 years ago in the fertile crescent. They were cultivating an early ancestor of wheat called emmer. Other grains popped up independently in what is now China (rice; ~10,000 years ago), and central America (corn; ~9,000 years ago). That's why people say humans have been eating grains for about 10,000 years.
The story is more complicated than the dates suggest, however. Although wheat had its origin 11,500 years ago, it didn't become widespread in Western Europe for another 4,500 years. So if you're of European descent, your ancestors have been eating grains for roughly 7,000 years. Corn was domesticated 9,000 years ago, but according to the carbon ratios of human teeth, it didn't become a major source of calories until about 1,200 years ago! Many American groups did not adopt a grain-based diet until 100-300 years ago, and in a few cases they still have not. If you are of African descent, your ancestors have been eating grains for 9,000 to 0 years, depending on your heritage. The change to grains was accompanied by a marked decrease in dental health that shows up clearly in the archaeological record.
Practically every plant food contains some kind of toxin, but grains produce a number of nasty ones that humans are not well adapted to. Grains contain a large amount of phytic acid for example, which strongly inhibits the absorption of a number of important minerals. Tubers, which were our main carbohydrate source for about 1.5 million years before agriculture, contain less of it. This may have been a major reason why stature decreased when humans adopted grain-based agriculture. There are a number of toxins that occur in grains but not in tubers, such as certain heat-resistant lectins.
Non-industrial cultures often treated their seeds, including grains, differently than we do today. They used soaking, sprouting and long fermentation to decrease the amount of toxins found in grains, making them more nutritious and digestible. Most grain staples are not treated in this way today, and so we bear the brunt of their toxins even more than our ancestors did.
From an evolutionary standpoint, even 11,500 years is the blink of an eye. Add to that the fact that many people descend from groups that have been eating grains for far less time than that, and you begin to see the problem. There is no doubt that we have begun adapting genetically to grains. All you have to do to understand this is look back at the archaeological record, to see the severe selective pressure (read: disease) that grains placed on its early adopters. But the question is, have we had time to adapt sufficiently to make it a healthy food? I would argue the answer is no.
There are a few genetic adaptations I'm aware of that might pertain to grains: the duplication of the salivary amylase gene, and polymorphisms in the angiotensin-converting enzyme (ACE) and apolipoprotein B genes. Some groups duplicated a gene that secretes the enzyme amylase into the saliva, increasing its production. Amylase breaks down starch, indicating a possible increase in its consumption. The problem is that we were getting starch from tubers before we got it from grains, so it doesn't really argue for either side in my opinion. The ACE and apolipoprotein B genes may be more pertinent, because they relate to blood pressure and LDL cholesterol. Blood pressure and blood cholesterol are both factors that respond well to low-carbohydrate (and thus low-grain) diets, suggesting that the polymorphisms may be a protective adaptation against the cardiovascular effects of grains.
The fact that up to 1% of people of European descent may have full-blown celiac disease attests to the fact that 7,000 years have not been enough time to fully adapt to wheat on a population level. Add to that the fact that nearly half of genetic Europeans carry genes that are associated with celiac, and you can see that we haven't been weeded out thoroughly enough to tolerate wheat, the oldest grain!
Based on my reading, discussions and observations, I believe that rice is the least problematic grain, wheat is the worst, and everything else is somewhere in between. If you want to eat grains, it's best to soak, sprout or ferment them. This activates enzymes that break down most of the toxins. You can soak rice, barley and other grains overnight before cooking them. Sourdough bread is better than normal white bread. Unfermented, unsprouted whole wheat bread may actually be the worst of all.
Wednesday, July 9, 2008
Another China Tidbit
A final note about the Chinese study in the previous post: the overweight vegetable-eaters (read: wheat eaters) exercised more than their non-vegetable-eating, thin neighbors. So although their average calorie intake was a bit higher, their expenditure was as well. So much for 'calories in, calories out'...
Although I speculated in the last post that affluent people might be eating more wheat and fresh vegetables, the data don't support that. Participants with the highest income level actually adhered to the wheat and vegetable-rich pattern the least, while low-income participants were most likely to eat this way.
Interestingly, education showed a (weaker) trend in the opposite direction. More educated participants were more likely to eat the wheat-vegetable pattern, while the opposite was true of less educated participants. Thus, it looks like wheat makes people more educated. Just kidding, that's exactly the logic we have to avoid when interpreting this type of study!
Although I speculated in the last post that affluent people might be eating more wheat and fresh vegetables, the data don't support that. Participants with the highest income level actually adhered to the wheat and vegetable-rich pattern the least, while low-income participants were most likely to eat this way.
Interestingly, education showed a (weaker) trend in the opposite direction. More educated participants were more likely to eat the wheat-vegetable pattern, while the opposite was true of less educated participants. Thus, it looks like wheat makes people more educated. Just kidding, that's exactly the logic we have to avoid when interpreting this type of study!
Sugar Tolerance: Does it Change
Over at the LivingAfterWLS Neighborhood we had a great question from our Neighbor Paula. She wants to know if our tolerance for sugar can change with the 5 Day Pouch Test. Take a look:Question from Paula:"Before the 5DPT, I could eat almost anything and not have a problem. (Which is where part of my problem came in and why I did the 5dpt.) The other night I ate a graham cracker with some peanut
Tuesday, July 8, 2008
Wheat in China
Dr. Michael Eades linked to an interesting study yesterday on his Health and Nutrition blog. It's entitled "Vegetable-Rich Food Pattern is Related to Obesity in China."
It's one of these epidemiological studies where they try to divide subjects into different categories of eating patterns and see how health problems associate with each one. They identified four patterns: the 'macho' diet high in meat and alcohol; the 'traditional' diet high in rice and vegetables; the 'sweet tooth' pattern high in cake, dairy and various drinks; and the 'vegetable rich' diet high in wheat, vegetables, fruit and tofu. The only pattern that associated with obesity was the vegetable-rich diet. The 25% of people eating closest to the vegetable-rich pattern were more than twice as likely to be obese as the 25% adhering the least.
The authors of the paper try to blame the increased obesity on a higher intake of vegetable oil from stir-frying the vegetables, but that explanation is juvenile and misleading. A cursory glance at table 3 reveals that the vegetable-eaters weren't eating any more fat than their thinner neighbors. Dr. Eades suggests that their higher carbohydrate intake (+10%) and higher calorie intake (+120 kcal/day) are responsible for the weight gain, but I wasn't satisfied with that explanation so I took a closer look.
One of the most striking elements of the 'vegetable-rich' food pattern is its replacement of rice with wheat flour. The 25% of the study population that adhered the least to the vegetable-rich food pattern ate 7.3 times more rice than wheat, whereas the 25% sticking most closely to the vegetable-rich pattern ate 1.2 times more wheat than rice! In other words, wheat flour had replaced rice as their single largest source of calories. This association was much stronger than the increase in vegetable consumption itself!
All of a sudden, the data make perfect sense. Wheat seems to destroy the metabolism of cultures wherever it goes. I think the reason we don't see the same type of association in American epidemiological studies is that everyone eats wheat. Only in a culture that has a true diversity of diet can you find a robust association like this. The replacement of rice with wheat may have caused the increase in calorie intake as well, subsequent to metabolic dysfunction. Clinical trials of low-carbohydrate diets as well as 'paleolithic diets' have shown good metabolic outcomes from wheat avoidance, although one can't be sure that wheat is the only culprit from those data.
I don't think the vegetables had anything to do with the weight gain, they were just incidentally associated with wheat consumption. But I do think these data argue against the commonly-held idea that vegetables protect against overweight.
It's one of these epidemiological studies where they try to divide subjects into different categories of eating patterns and see how health problems associate with each one. They identified four patterns: the 'macho' diet high in meat and alcohol; the 'traditional' diet high in rice and vegetables; the 'sweet tooth' pattern high in cake, dairy and various drinks; and the 'vegetable rich' diet high in wheat, vegetables, fruit and tofu. The only pattern that associated with obesity was the vegetable-rich diet. The 25% of people eating closest to the vegetable-rich pattern were more than twice as likely to be obese as the 25% adhering the least.
The authors of the paper try to blame the increased obesity on a higher intake of vegetable oil from stir-frying the vegetables, but that explanation is juvenile and misleading. A cursory glance at table 3 reveals that the vegetable-eaters weren't eating any more fat than their thinner neighbors. Dr. Eades suggests that their higher carbohydrate intake (+10%) and higher calorie intake (+120 kcal/day) are responsible for the weight gain, but I wasn't satisfied with that explanation so I took a closer look.
One of the most striking elements of the 'vegetable-rich' food pattern is its replacement of rice with wheat flour. The 25% of the study population that adhered the least to the vegetable-rich food pattern ate 7.3 times more rice than wheat, whereas the 25% sticking most closely to the vegetable-rich pattern ate 1.2 times more wheat than rice! In other words, wheat flour had replaced rice as their single largest source of calories. This association was much stronger than the increase in vegetable consumption itself!
All of a sudden, the data make perfect sense. Wheat seems to destroy the metabolism of cultures wherever it goes. I think the reason we don't see the same type of association in American epidemiological studies is that everyone eats wheat. Only in a culture that has a true diversity of diet can you find a robust association like this. The replacement of rice with wheat may have caused the increase in calorie intake as well, subsequent to metabolic dysfunction. Clinical trials of low-carbohydrate diets as well as 'paleolithic diets' have shown good metabolic outcomes from wheat avoidance, although one can't be sure that wheat is the only culprit from those data.
I don't think the vegetables had anything to do with the weight gain, they were just incidentally associated with wheat consumption. But I do think these data argue against the commonly-held idea that vegetables protect against overweight.
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