Dietary cholesterol and blood serum cholesterol

The idea that dietary cholesterol increases blood cholesterol achieved mainstream acceptance due in large part to the efforts of Dr. Ancel Keys. As a result of his lobbying, the American Heart Association recommends eating less than 300mg of cholesterol per day.

Here are some cholesterol measures from UC San Francisco:

• One large egg: ~200 mg of cholesterol
• 3.5 oz of shrimp: 194 mg of cholesterol
• 3.5 oz of veal: 135 mg of cholesterol
• 3.5 oz of chicken, no skin: 93 mg of cholesterol
• 3.5 oz of pork tenderloin: 79 mg of cholesterol
• 3.5 oz of ground beef: 9 mg of cholesterol
• 8 oz of whole milk: 33 mg of cholesterol

You can see how eggs got a bad rap, especially since those portion sizes are small by U.S. standards. And why this recommendation led to a low protein/high carbohydrate diet.

But what does the research suggest?

A meta study published in 1956 found no correlation

In 1955, Keys and four other scientists submitted Diet And Serum Cholesterol In Man: Lack Of Effect Of Dietary Cholesterol to the Journal of Nutrition.

Read that title again: Lack Of Effect Of Dietary Cholesterol.

It is concluded that in adult men the serum cholesterol level is essentially independent of the cholesterol intake over the whole range of natural human diets. It is probable that infants, children and women are similar.

Here are the findings:

1. An analysis of four cross-sectional surveys of men in Minnesota “showed no relationship between dietary cholesterol and the total serum cholesterol concentration over most of the ordinary cholesterol intake range characteristic of American diets.
2. Two surveys of men living on the island of Sardinia whose diets had markedly different cholesterol intake did not show any difference in the serum cholesterol concentrations; comparisons were made of men of the same age, physical activity, relative bodyweight, and general dietary pattern.
3. A 4-year research study of two groups of men showed no difference their cholesterol serum values. Group 1 had 33 men with diets that were consistently very low in cholesterol. Group 2 had 35 men of the same age and economic status but their diets that were very high in cholesterol.
4. A study of two groups of men failed to show any serum level dietary response at 4 and 12 months. In group one, 23 men voluntarily doubled their cholesterol intakes; in group 2, 41 halved theirs. For both groups the rest of the diet was more or less constant.
5. A detailed study of the complete dietary intake of 119 Minnesota businessman showed no significant increase in serum cholesterol despite having the businessmen increae their dietary cholesterol intake.
6. In four completely controlled experiments, the addition to or removal of 500 to 600 mg of cholesterol daily had no effect on serum classroom. The experiments focused on a rice-fruit (low dietary cholesterol) diet and an ordinary American diet (high dietary cholesterol).
7. In a completely controlled experiment on five physically healthy men, changing from a rice-fruit diet containing 500 mg of cholesterol to the same diet with no cholesterol showed no affect on the serum cholesterol level.
8. In a similar experiment with 13 men, boosting cholesterol intake to 374 mg/day 1369 mg/day revealed no significant effect serum cholesterol levels. In another 12 man group, the an equivalent lowering of dietary cholesterol also had no effect on the blood serum.

Sixty years ago, researchers failed to show correlation — much less causation — between dietary cholesterol and blood serum levels. Yet a squeaky wheel, Keys, pushed his recommendation that Americans reduce dietary fat. The rest is history.

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