Theory on dietary essential amino acids and LDL

Dr. Kummerow, an honorary professor of biosciences at the University of Illinois, made his original discovery on causal relationship between low-density lipoprotein (LDL), cholesterol and dietary level of essential amino acids already more than 50 years ago (see, J Nutr. November 1961;75:319-329).

LDL is well known as the "bad cholesterol" and its increase in blood circulation is considered as one of the key indicators of heart disease. However, Dr. Kummerow claims that a high LDL is “only” a consequence of a diet lacking in essential amino acids.

As a simple background, the key protein component of LDL is apolipoprotein B, which serves to bind the lipoprotein particles to LDL-specific receptors on the cell surfaces. The LDL particles are used as a structural component of cell membranes or converted to steroid hormones. Apoliprotein B is the major protein in all lipoproteins, except high density lipoprotein (HDL; the good one).

In his research spanning 5 decades, Dr. Kummerow noticed that apoliprotein B inversely depended on dietary supply of the amino acid tryptophan. He further speculated that a high LDL level indicated a lack of essential amino acids, mainly tryptophan, in our diet. There is an interesting consequence of this thinking, because the current medical practitioners advice patients to avoid foods that are rich in tryptophan, for example eggs, turkey, nuts.

Should we believe Dr. Kummerow? Well, since he will be soon a healthy 102-old man, perhaps we should, especially as he advice concerns tryptophan which is also needed to prevent cases of mild depression and improve sleep (besides being an irreplaceable component of proteins).

Finally, some of other general ideas Dr. Kummerow holds are worth noticing. For example, “…A diet low in dietary cholesterol and in fats that raise blood cholesterol will not provide long-term prevention of coronary heart disease. Protein from animal products normally needs to be in the diet because this contains all the essential amino acids and essential fatty acids, and has the best biological value. Reducing dietary cholesterol intake to a level at or below 200 mg a day will result in a less nutritious diet for most people. A diet low in dietary cholesterol and cholesterol-raising fats is likely to be deficient in protein, vitamins and minerals.”