Dietary Guidelines, Cholesterol & You!
Jeff Novick, MS, RDN
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.
http://www.washingtonpost.com/blogs/won ... l/?hpid=z1Have we been wrong all these years?
As with my recent discussions on saturated fat, part of this discussion is whether cholesterol is harmful in-and-of-itself as a component of the diet or is cholesterol just a marker for an unhealthy dietary pattern high in animal products, which would also be high in animal protein, high in saturated fat, low in fiber, etc. Is cholesterol a harmful component that should be reduced or is it a marker of an unhealthy dietary pattern that should be switched to a healthy plant-based dietary pattern. Is it a harmful component, a marker or both.
This seems to be the issues.
To clear this up, let's look at two studies in particular that address whether dietary 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. (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...
http://m.ajcn.nutrition.org/content/25/ ... pdf#page=1This was a very well done study that used controlled formula diets in a very controlled setting over 11 weeks. You can read the details of the study in the "Materials and methods" section. Basically, the subjects, who were inmates of the Philadelphia prison system were fed their usual prison diet for 7 days, then over the next 7 days, had their diets gradually switched over to an experimental formula diet that contained no cholesterol. Then, for 21 days, they were all kept exclusively on the cholesterol free formula diet. At this point, the 7 inmates with the highest blood cholesterol levels and the 7 with 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 the amount of cholesterol in it. One groups formula had no cholesterol, the second had 106 mg, the third 212 mg and the fourth 317 mg, each per 1000 calories. The results showed that for each 100 mg/1000 calories increase in dietary cholesterol, serum cholesterol increased 12 mg per 100 ml with the serum 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, who I have discussed before.
The second one, Inactivating Mutations in NPC1L1 and Protection from Coronary Heart Disease, was just recently published in November of 2014 in the New England Journal of Medicine. (N Engl J Med 2014; 371:2072-2082November 27, 2014DOI: 10.1056/NEJMoa1405386). You can see a copy of the abstract of study online here…
http://www.nejm.org/doi/pdf/10.1056/NEJMoa1405386and you can read about it here
http://news.wustl.edu/news/Pages/27658.aspxBasically, there are people who as a result of a genetic variant have LDL levels that average 12 mg/dl lower than the general population, which is about a 10% percent reduction from average LDL levels. It turns out that they also have about half the risk of coronary heart disease as does 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 the diet, 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.
Short-Term Reductions in Serum Lipids through Diet and Exercise
New England Journal of Medicine, 323: 1142, 1990;
http://www.nejm.org/doi/full/10.1056/NE ... 0183231613Plasma Lipid Lowering in Short-term Life-style Change
Arch Intern Med. 1991;151(7):1275-1276. doi:10.1001/archinte.1991.00400070053004.
http://archinte.jamanetwork.com/article ... eid=615244(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 the diet and a marker for an unhealthy animal-based dietary pattern. Recommendations to reduce &/or eliminate cholesterol should remain and the best way to do that is to switch from a unhealthy animal-based dietary pattern based to a healthy lower fat, lower calorie-dense dietary dietary pattern based predominately on minimally processed plant foods.
In Health
Jeff
Special thanks to my friend and colleague Jay Kenny, PhD, RD, who reminded me of the 1972 Mattson study.