Since vegetable foodstuffs are nearly cholesterol free, the intake of cholesterol via nutrition results from the consumption of animal foodstuffs.
Endogenous cholesterol production is regulated via the insulin/glucagon ratio. Test persons with increased cholesterol concentrations were also shown to have a higher insulin/glucagon ratio than test persons with normal cholesterol values. (21)
The composition of the food proteins has an influence on the release of the metabolism hormones insulin and glucagon. Animal proteins stimulate the release of insulin and activate HMG-CoA reductase, the limiting enzyme for cholesterol synthesis.
Vegetable proteins usually contain more arginine than lysine. Animal proteins on the other hand contain more lysine and leucine than vegetable proteins. A cholesterol-lowering effect especially of soy protein was detected in several studies, which was mainly attributed to the high arginine concentration of this vegetable protein. (22, 23, 24)
A high intake of lysine in form of animal proteins causes arginine to be incorporated into atherogenic apoproteins like Apo E more frequently. These proteins are transport molecules for lipids and cholesterol.
Vegetarian diets have a positive effect on cholesterol concentrations. Some studies were able to discover a more favorable HDL/LDL ratio. (25, 26, 27)
The LDL cholesterol of vegetarians has proved less susceptible to oxidization than that of non-vegetarians. This is attributed to the high intake of antioxidant substances in vegetarians.(28)
- Hubbard R et al: Effect of dietary protein on serum insulin and glucagon levels in hyper- and normocholesterolemic men; Atherosclerosis 1989 Mar; 76(1): 55-61
- Sanchez A et al: Plasma amino acids and the insulin/ glucagon ratio as an explanation for the dietary protein modulation of atherosclerosis; Med Hypotheses 1991 Aug; 36(4): 324-9
- Carroll KK et al: Soy consumption and cholesterol reduction: review of animal and human studies; J Nutr 1995 Mar; 125(3 Suppl): 594S-597S
- Wong WW et al: Cholesterol-lowering effect of soy protein in normocholesterolemic and hypercholesterolemic men, Am J Clin Nutr 1998 Dec; 68(6 Suppl): 1385S-1389S
- Robinson F et al: Changing from a mixed to self-selcted vegetarian diet-influence on blood lipids; J Hum Nutr Diet 2002 Oct; 15(5): 323-9
- Hoffmann I et al: Giessen Wholesome Nutrtion Stuudy: relation between a health-conscious diet and blood lipids; Eur J Clin Nutr 2001 Oct; 55(10): 887-95
- Bederova A et al: Comparison of nutrient intake and corresponding biochemica parameters in adolescent vegetarians and non-vegetarians; Cas Lek Cesk 2000 Jul 5; 139(13): 396-400
- Nagyova A et al: LDL and HDL oxidation and fatty acid composition in vegetarians; Ann Nutr Metab 2001; 45(4): 148-51