Proponents of the cholesterol theory of cardiovascular disease believe that cholesterol and saturated fat in the diet cause elevations in plasma cholesterol levels and that this in turn causes the development of atherosclerosis and cardiovascular disease. This theory was popularised by Ancel Keys in the 1950’s and 1960’s in a series of studies where intakes of cholesterol and saturated fat were shown to correlate with cardiovascular disease rates in a number of countries. Despite protestations to the contrary and a concerted propaganda effort on the part of the proponents of this theory, since this time evidence has accumulated to show that dietary cholesterol and saturated fat has little effects on plasma levels of cholesterol. Much of the original work on the cholesterol theory of cardiovascular disease, including the studies by Ancel Keys, have been discredited due to methodological flaws. In particular, the deliberate manipulation of the diets of subject to add confounding variables has been exposed.
The best way to ascertain if red meat, eggs or anything else is a cause of cholesterol changes in the plasma of human is to allow subject to consume their normal diets, but just to ask them to substitute one protein source for another. This is advantageous because it limits the interference in the subjects normal lives and gives a better representation of normal free living conditions. For example in one study1, researchers investigated the changes to total cholesterol levels in a group of 47 healthy male volunteers caused by changes to the intakes of meat in their diet. Subjects consumed either beef for 3 months, chicken and fish for 3 months or pork for 3 months as their only source of meat. Researchers also included a 3 month interval period with no dietary stipulation. The rest of their diets were not controlled and they were allowed to continue their normal eating patterns. The results showed that the mean total cholesterol levels did not change between treatments and meat type therefore had no influence on plasma cholesterol levels.
When the authors performed the same experiment in 29 healthy females, they found a small but significant difference in mean values for total cholesterol levels. However, pooling the data of the females with the males removed any significant changes. The authors noted that serum triglyceride levels were highly variable and that high density lipoprotein (HDL) cholesterol levels showed inconsistent changes with some individuals experiencing increases and some experiencing decreases. The authors limited the subjects to one egg per day to prevent them playing a role in the study, but apart from this control, no other restrictions were placed on the subjects in terms of food selection or energy intake. This study is therefore a good representation of the free living conditions experienced by normal people. The fact that swapping meats did not modify cholesterol levels suggests that recommendations made by proponents of the cholesterol theory of cardiovascular disease to limit red meat intakes are unfounded.
Dr Robert Barrington’s Nutritional Recommendation: Avoiding red meat, eggs or any other cholesterol and saturated fat containing food will not cause alterations in plasma cholesterol levels. This is has been shown in healthy free living populations in well designed studies. Rather than encouraging people to avoid red meat, it should perhaps be emphasised that the quality of the meat is more important than the type or quantity of the meat. Organic, free range and grass fed meats are nutritionally superior to conventionally grown meat because the fatty acid profile favours inclusion of omega 3 fats in the former. In addition, organic meats should be free of pesticide residues and this confers health benefits in the long term. High fat meats are a common food in southern France, yet their rates of cardiovascular disease are low. The maasai too eat a diet containing very high amounts of cholesterol and saturated fat and yet have almost no cardiovascular disease amongst their populations. Eating red meat in moderation therefore is recommended for its nutritional content as long as high quality sources are sourced.
RdB
