Dietary Guidelines, Cholesterol & You!
As we have all heard, it seems the upcoming Dietary Guidelines will withdraw their recommendation to limit dietary cholesterol, which first appeared as a recommendation as part of the American Heart Association guidelines in 1961.
Have we been wrong all these years?
As with my recent discussions on saturated fat, part of this discussion iswhether cholesterol is harmful in-and-of-itself as a component of the diet oris cholesterol just a marker for an unhealthy dietary pattern high in animalproducts, which would also be high in animal protein, high in saturated fat,low in fiber, etc. Is cholesterol a harmful component that should be reducedor is it a marker of an unhealthy dietary pattern that should be replaced witha healthy plant-based dietary pattern, or both?
This seems to be the issue.
To clear this up, let's look at two studies in particular that address whetherdietary cholesterol matters, one very old and one very new.
The first one, Effect of dietary cholesterol on serum cholesterol in man, was done in 1972 and published in The American Journal of Clinical Nutrition. (JUN 25: 1972, pp. 589-594.) You can find a full text copy of the study online here for free.
This was a very well done study that used controlled formula diets in a verycontrolled setting over 11 weeks. You can read the details of the study inthe "Materials and methods" section. Basically, the subjects, who wereinmates of the Philadelphia prison system were fed their usual prison diet for7 days, then over the next 7 days, had their diets gradually switched over toan experimental formula diet that contained no cholesterol. Then, for 21days, they were all kept exclusively on the cholesterol free formula diet. Atthis point, the 7 inmates with the highest blood cholesterol levels and the 7with the lowest blood cholesterol levels were removed from the study. The remaining 56 subjects were divided into 4 groups. Over the next 6 weeks,each group was fed the exact same diet with the only difference being theamount of cholesterol in it. One group’s formula had no cholesterol; thesecond had 106 mg, the third 212 mg and the fourth 317 mg, each per 1000calories. The results showed that for each 100 mg/1000 calories increase indietary cholesterol, serum cholesterol increased 12 mg per 100 ml with theserum cholesterol of group 4 increasing 25%.
The conclusion stated, "relatively greater importance should be given to dietary cholesterol as a determinant of serum cholesterol in the United States population."
That was in 1972 and their results were in line with the work of Keys and Hegsted, which I have discussed before.
The second one, Inactivating Mutations in NPC1L1 and Protection fromCoronary Heart Disease, was just recently published in November of 2014 inthe New England Journal of Medicine. (2014; 371:2072-2082 November 27, 2014 DOI: 10.1056/NEJMoa1405386). You can see acopy of the abstract of the study online here. And you can read about it here.
Basically, there are people who as a result of a genetic variant have LDLlevels that average 12 mg/dl lower than the general population, which isabout a 10% percent reduction from average LDL levels. It turns out thatthey also have about half the risk of coronary heart disease as the general population.
So, let’s put all of this together.
As we saw in the first study, dietary cholesterol, even as a component of thediet, raised serum cholesterol about 25%. Interestingly, this is about the same percentage we see cholesterol and LDL lowered in studies on this way of eating.
These two studies show an average drop of 23% in total cholesterol and LDL“bad” cholesterol in just 21 days.
New England Journal of Medicine, 323: 1142, 1990;
Arch Intern Med. 1991;151(7):1275-1276.doi:10.1001/archinte.1991.00400070053004.
(NOTE: The 23% if an average and we have seen drops of 50% or more in those who come to the programs with the highest cholesterols and LDLs).
So, yes, cholesterol, like saturated fat, is both a harmful component of thediet and a marker for an unhealthy animal-based dietary pattern.Recommendations to reduce &/or eliminate cholesterol should remain andthe best way to do that is to switch from an unhealthy animal-based dietary pattern to a healthy plant-based dietary pattern.