Saturated Fat and Health: a Brief Literature Review, Part I

Even years ago, when I watched my saturated fat intake, I always had a certain level of cognitive dissonance about it. I knew that healthy non-industrial cultures often consumed large amounts of saturated fat. For example, the Masai of East Africa, who traditionally subsist on extremely fatty milk, blood and meat, do not appear to experience heart attacks. Their electrocardiogram readings are excellent and they have the lowest level of arterial plaque during the time of their lives when they are restricted (for cultural reasons) to their three traditional foods. They get an estimated 33% of their calories from saturated animal fat.

Then there are the Pacific islanders, who often eat large amounts of highly saturated coconut. Kitavans get 17% of their calories from saturated fat (Americans get about 10% on average), yet show no trace of heart disease, stroke or overweight. The inhabitants of the island of Tokelau, who I learned about recently, eat more saturated fat than any other culture I'm aware of. They get a whopping 55% of their calories from saturated fat! Are they keeling over from heart attacks or any of the other diseases that kill people in modern societies? Apparently not. So from the very beginning, the theory faces the problem that the cultures consuming the most saturated fat on Earth have an undetectable frequency of heart attacks and other modern non-communicable diseases.

Humans have eaten saturated animal fat since our species first evolved, and historical hunter-gatherers subsisted mostly on animal foods. Our closest recent relatives, neanderthals, were practically carnivores. Thus, the burden of proof is on proponents of the theory that saturated fat is unhealthy.

There have been countless studies on the relationship between saturated fat and health. The first studies were epidemiological. Epidemiological studies involve collecting data from one or more populations and seeing if any specific factors associate with the disease in question. For example, the Framingham Heart study collected data on diet, lifestyle and mortality from various diseases and attempted to connect diseases to lifestyle factors. This type of study is useful for creating hypotheses, but it can only determine associations. For example, it can establish that smokers tend to die more often from heart disease than non-smokers, but it can't determine that smoking is actually the cause of heart disease. This is because multiple factors often travel together. For example, maybe smokers also tend to take care of themselves less in other ways, sleeping less, eating more sugar, etc.

Epidemiological data are often incorrectly used to demonstrate causality. This is a big problem, and it irritates me to no end. There's only one way to show conclusively that a diet or lifestyle factor actually causes something else: a controlled trial. In a controlled trial, researchers break participants into two groups: an intervention group and a control group. If they want to know the effect of saturated fat on health, they will advise the participants in each group to eat different amounts of saturated fat, and keep everything else the same. At the end of the trial, they can determine the effect of saturated fat on health because it was the only factor that differed between groups. In practice, reducing saturated fat also involves either increasing unsaturated fat or decreasing total fat intake, so it's not perfect.

I'm not going to review the epidemiological data because they are contradictory and they are "lesser evidence" compared to the controlled trials that have been conducted. However, I will note that Dr. Ancel Keys' major epidemiological study linking saturated fat consumption to heart disease, the "Seven Countries" study, has been thoroughly discredited due to the omission of contradictory data (read: the other 15 countries where data were available). This was the study that sparked the anti-saturated fat movement. Older epidemiological studies and those conducted internationally tend to find nonexistent or weak links between saturated fat and health problems, while more recent American studies, such as the Nurses' Health study, have sometimes found strong associations. I'll address this phenomenon in another post.

In the next post, I'll get into the meaty data: the controlled trails evaluating the effect of saturated fat on health.

Thanks to Rockies for the CC photo.

Vitamin K2, menatetrenone (MK-4)

Weston Price established the importance of the MK-4 isoform of vitamin K2 (hereafter, K2) with a series of interesting experiments. He showed in chickens that blood levels of calcium and phosphorus depended both on vitamin A and K2, and that the two had synergistic effects on mineral absorption. He also showed that chickens preferred eating butter that was rich in K2 over butter low in K2, even when the investigators couldn't distinguish between them. Young turkeys fed K2-containing butter oil along with cod liver oil (A and D) also grew at a much faster rate than turkeys fed cod liver oil alone.

He hypothesized that vitamin A, vitamin D and vitamin K2 were synergistic and essential for proper growth and subsequent health. He particularly felt that the combination was important for proper mineral absorption and metabolism. He used a combination of high-vitamin cod liver oil and high-vitamin butter oil to heal cavities, reduce oral bacteria counts, and cure numerous other afflictions in his patients. He also showed that the healthy non-industrial groups he studied had a much higher intake of these fat-soluble, animal-derived vitamins than more modern cultures.

Price found an inverse correlation between the levels of K2 in butter and mortality from cardiovascular disease and pneumonia in a number of different regions. A recent study examined the relationship between K2 (MK-4 through 10) consumption and heart attack risk in 4,600 Dutch men. They found a strong inverse association between K2 consumption and heart attack mortality risk. Men with the highest K2 consumption had a whopping 51% lower risk of heart attack mortality and a 26% lower risk of death from all causes compared to men eating the least K2! Their sources of K2 MK-4 were eggs, meats and dairy. They obtained MK-5 through MK-10 from fermented foods and fish. The investigators found no association with K1, the form found in plants.

Perigord, France is the world's capital of foie gras, or fatty goose liver. Good news for the bon vivants: foie gras turns out to be the richest known source of K2. Perigord also has the lowest rate of cardiovascular mortality in France, a country already noted for its low CVD mortality.

Rats fed warfarin, a drug that inhibits K2 recycling, develop arterial calcification. Feeding the rats K2 completely inhibits this effect. Mice lacking matrix Gla protein (MGP), a vitamin K-dependent protein that guards against arterial calcification, develop heavily calcified aortas and die prematurely. So the link between K2 and cardiovascular disease is a very strong one.

Mammals can synthesize K2 MK-4 from K1, but humans seem to be bad at it since most of us are K2 deficient despite eating ample K1. This suggests that through evolution, we lost the ability to synthesize K2 in sufficient amounts because we always obtained it abundantly in our diets from nutrient-dense animal tissues.

The synergism Weston Price observed between vitamins A, D and K2 now has a solid mechanism. In a nutshell, vitamins A and D signal the production of some very important proteins, and K2 is required to activate them once they are made. Many of these proteins are involved in mineral metabolism, thus the effects Price saw in his experiments and observations in non-industrialized cultures. For example, osteocalcin is a protein that organizes calcium and phosphorus deposition in the bones and teeth. It's produced by cells in response to vitamins A and D, but requires K2 to perform its function. This suggests that the effects of vitamin D on bone health could be amplified greatly if it were administered along with K2. By itself, K2 is already highly protective against fractures in the elderly. It works out perfectly, since K2 also protects against vitamin D toxicity.

I'm not going to go through all the other data on K2 in detail, but suffice it to say it's very very important. I believe that K2 is a 'missing link' that explains many of our modern ills, just as Weston Price wrote. Here are a few more tidbits to whet your appetite: K2 may affect glucose control and insulin release (1, 2). It's concentrated in the brain, serving an as yet unknown function.

Hunter-gatherers didn't have multivitamins, they had nutrient-dense food. As long as you eat a natural diet containing some vegetables and some animal products, and lay off the processed grains, sugar and vegetable oil, the micronutrients will take care of themselves.

Vitamin K2, MK-4 is only found in animal products. The best sources known are grass-fed butter from cows eating rapidly growing grass, and foie gras. K2 tends to associate with beta-carotene in butter, so the darker the color, the more K2 it contains (also, the better it tastes). Fish eggs, other grass-fed dairy, shellfish, insects and other organ meats are also good sources. Chris Masterjohn compiled a list of food sources in his excellent article on the Weston Price foundation website. I highly recommend reading it if you want more detail. K2 MK-7 is found abundantly in natto, a type of fermented soybean, and seems to have some of the same effects as MK-4 on bone health in clinical trials. However, it is not the from of K2 that mammals synthesize for themselves so I'm not convinced it's the real thing.

Finally, you can also buy K2 supplements. The best one is butter oil, the very same stuff Price used to treat his patients. I have used this one personally, and I noticed positive effects on my skin overnight. Thorne research makes a synthetic liquid K2 MK-4 supplement that is easy to dose drop-wise to get natural amounts of it. Other K2 MK-4 supplements are much more concentrated than what you could get from food so I recommend avoiding them. I am generally against supplements, but I've ordered the Thorne product for a little self-experimentation. I want to see if it has the same effect on my skin as the butter oil (update- it does).

The French Paradox

According to the World Health Organization, 82 out of every 100,000 French men between ages 35 and 74 died as a result of cardiovascular disease (CVD) in the year 2000. In that same year, 216 out of 100,000 men between the same ages in the U.S. succumbed to the same disease.

According to the Food and Agriculture Organization of the UN, during roughly the same time period, the average French person ate slightly more total fat and almost three times more animal fat than the average American. Animal fats came from dairy, lard, red meats, fish and poultry, and contributed to a much higher overall saturated fat intake in the French. This has been called the "French paradox", the paradox being that saturated fat is supposed to cause CVD.

Researchers have been scrambling to identify the factor that is protecting French hearts from the toxic onslaught of saturated fat. What could possibly be preventing the buttery sludge coursing through their arteries from killing them on the spot? One hypothesis is that wine is protective. Although the modern French don't actually drink much more alcohol than Americans on average, wine contains a number of molecules that are potentially protective.

One of these that has gotten a lot of attention is resveratrol, an activator of SIRT1, a deacetylase enzyme that is involved in stress resistance and lifespan regulation. But lo and behold, it turns out that there isn't enough of it in wine to be helpful. Now researchers are turning their attention to a class of molecules called procyanidins, but I suspect that this will turn up negative as well. The protective molecule is probably ethanol, but no one wants to hear that because it doesn't resolve the paradox.

As a person with a French background who has spent quite a bit of time in France, the notion of a French paradox is insulting. It implies that the French are eating an unhealthy diet, but are somehow miraculously protected by a compound they're ingesting by accident. Any French person will tell you there is no paradox. When you make a commitment to seek out the freshest, most delicious ingredients available and cook them yourself, your diet will be healthier than if you count the grams of this and that on your TV dinner.

There's more. Americans consume almost twice the amount of sugar as the average French person. I find this surprising, given the large amount of sugar I've seen on French tables, but I think it speaks to the huge amount of sugar we consume in the US. Much of it probably comes from the high-fructose corn syrup in soda. I'll save my rant about that for another time.

Another thing that stands out about French food habits is the absence of snacking. Mealtimes in France tend to be well-defined, and grazing is looked down upon. I think this is probably essential for maintaining adequate insulin sensitivity in the face of (delicious) refined carbohydrates like baguette.

And finally, the French enjoy their food more than the average nation. I wouldn't underestimate the value of this for health and overall well-being.

So what was the paradox again? I can't remember. Maybe a more parsimonious explanation of the data is that saturated fat isn't so bad after all, and enjoying wholesome food and limiting sugar is the true prescription for health.

Thanks to Gaetan Lee for the creative commons photo.