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Myth #1: Eating cholesterol and saturated fat raises cholesterol levels in the blood.
Most of us grew up being told that foods like red meat, eggs and bacon raise our cholesterol levels. This idea is so deeply ingrained in our cultural psyche that few people even question it. But is it really true?
The diet-heart hypothesis—which holds that eating cholesterol and saturated fat raises cholesterol in our blood—originated with studies in both animals and humans more than half a century ago. However, more recent (and higher quality) evidence doesn’t support it.
On any given day, we have between 1,100 and 1,700 milligrams of cholesterol in our body. 25% of that comes from our diet, and 75% is produced inside of our bodies by the liver. Much of the cholesterol that’s found in food can’t be absorbed by our bodies, and most of the cholesterol in our gut was first synthesized in body cells and ended up in the gut via the liver and gall bladder. The body tightly regulates the amount of cholesterol in the blood by controlling internal production; when cholesterol intake in the diet goes down, the body makes more. When cholesterol intake in the diet goes up, the body makes less.
This explains why well-designed cholesterol feeding studies (where they feed volunteers 2-4 eggs a day and measure their cholesterol) show that dietary cholesterol has very little impact on blood cholesterol levels in about 75% of the population. The remaining 25% of the population are referred to as “hyper-responders”. In this group, dietary cholesterol does modestly increase both LDL (“bad cholesterol” and HDL (“good cholesterol”), but it does not affect the ratio of LDL to HDL or increase the risk of heart disease. (2)
In other words, eating cholesterol isn’t going to give you a heart attack. You can ditch the egg-white omelettes and start eating yolks again. That’s a good thing, since all of the 13 essential nutrients eggs contain are found in the yolk. Egg yolks are an especially good source of choline, a B-vitamin that plays important roles in everything from neurotransmitter production to detoxification to maintenance of healthy cells. (3) Studies show that up to 90% of Americans don’t get enough choline, which can lead to fatigue, insomnia, poor kidney function, memory problems and nerve-muscle imbalances. (4)
In my video, Eggs vs. Cigarettes in Atherosclerosis, I profiled a study showing that both smoking and eating eggs can harm our arteries. But even egg yolks alone were associated with artery-clogging plaque buildup nearly two thirds as bad as smoking.
This certainly ruffled some feathers.
Yes, eggs are by far the number one source of cholesterol in the American diet, but some letters to the editor protested that dietary cholesterol may have very little impact on blood cholesterol levels, citing a study published in 1971 performed on eight people. But if one looks at dozens of studies together, covering hundreds of study subjects, we find that blood cholesterol concentration is “clearly increased by added dietary cholesterol.” In my video, Debunking Egg Industry Myths, there is an extreme example just to illustrate: a year in the life of a study subject taken on and off eggs. First, the researchers take him off eggs, putting him on a cholesterol-free diet, and his blood cholesterol plummets within just three weeks. Then they give him lots of eggs, and his cholesterol shoots back up, stays high until they take the eggs away and put him back on the cholesterol free diet, and so on and so forth. The researchers were essentially turning his high blood cholesterol on and off like a light switch (made out of eggs).
Of course the only reason we care about our cholesterol levels or how much plaque is building up inside our arteries is because we want to avoid the consequences, like a heart attack. So do eggs increase our risk of cardiovascular disease? The latest meta-analysis, the latest compilation of all the best studies on egg consumption and risk of heart disease going back to 1930, found that, overall, those who ate the most eggs had a 19% increased risk of cardiovascular disease, a 68% increased risk of diabetes, and, once you have diabetes, an even greater 85% increased risk of heart disease. It didn’t take much; less than a single egg a day was associated with a significantly increased risk of heart disease. Just over half an egg a day may increase heart disease risk 6% (40% in separated diabetes patients), and the risk of diabetes by 29%. The researchers conclude that their findings support the American Heart Association dietary guidelines, which advise restricted egg consumption in adults for preventing cardiometabolic disease, like diabetes, our seventh leading cause of death, and heart disease, our number one killer.
A reduction of animal fat and an increase of vegetable fat in the diet is said to lower the blood cholesterol. This is correct, but the effect of such dietary changes is very small. Ramsay and Jackson reviewed 16 trials using diet as intervention. They concluded that the so-called step-I diet, which is similar to the dietary advices that are given nationwise by the health authorities in many countries, lower the serum cholesterol by 0 to 4% only. There are more effective diets, but they are unpalatable to most People.
Studies of African tribes have shown that intakes of enormous amounts of animal fat do not necessarily raise blood cholesterol; on the contrary it may be very low. Samburu people, for instance, eat about a pound of meat and drink almost two gallons of raw milk each day during most of the year. Milk from the African Zebu cattle is much fatter than cow’s milk, which means that the Samburus consume more than twice the amount of animal fat than the average American, and yet their cholesterol is much lower, about 170 mg/dl (4.3 meq/l).
According to the Masai people in Kenya, vegetables and fibers are food for cows. They themselves drink half a gallon of Zebu milk every day and their parties are sheer orgies of meat. On such occasions several pounds of meat per person is not unusual. Inspite of that the cholesterol of the Masai tribesmen is among the lowest ever measured in the world, about fifty percent of the value of the average American.
Shepherds in Somalia eat almost nothing but milk from their camels. About a gallon and a half a day is normal, which amounts to almost one pound of butter fat, because camel’s milk is much fatter than cow’s milk. But although more than sixty percent of their energy consumption comes from animal fat, their mean cholesterol is only about 150 mg/dl (3.8 meq/l), far lower than in most Western people.
Proponents of the diet-heart idea say that these African tribesmen are accustomed to their diet and that their organisms have inherited a cleverness to metabolize cholesterol. However, a study of Masai people who had lived for a long time in the Nairobi metropolis showed this to be wrong. If the low cholesterol of the Masai tribesmen was inherited, it should have been even low erin Nairobi, because here their diet with all certainty included less animal fat than the diet of the Masai tribesmen. But the mean cholesterol level in twentysix males in Nairobi was twenty-five percent higher than that of their cattle-breeding colleagues at the countryside.
And there is more evidence. Although it is possible to change blood cholesterol a little in laboratory experiments and clinical trials by dieting, it is impossible to find any relationship between the make up of the diet and the blood cholesterol of individuals, who are not participating in a medical experiment. In other words, individuals who live as usual and eat their food without listening to doctors or dieticians, show no connection between what they eat and the level of their blood cholesterol.
If the diet-heart idea were correct individuals who eat great amounts of animal fat would have higher cholesterol than those who eat small amounts; and individuals who eat small amounts of vegetable fat should have higher cholesterol than those who eat great amounts. If not, there is no reason to meddle with people’s diet.
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