A full 16% of a lean individual’s body weight is protein. Most of us know that protein’s functions include being a part of our structure (i.e. muscles), but it also represents some of our hormones, enzymes, blood-clotting factors, lipoproteins and visual pigments.
Many diet plans have been high-protein (i.e. Atkins) which appeared to work in the short-term, but it was feared such food intake would raise triglycerides (TG) and/or cholesterol, putting individuals at greater risk for cardiovascular disease. They were also difficult to follow long-term.
Comparisons of Popular Diets and Heart Disease Risks
A study 1 compared 8 diets on how each affected weight and related risk factors. Diets included Weight Watchers, New Glucose Revolution, Atkins, Ornish and US government’s 2005 Food Guide Pyramid. Subjects were overweight premenopausal women. Results found that women on the lowest carbohydrate and highest protein plan (Atkins) had the most weight loss with accompanying favorable changes in risk factors. Weight loss does lower risk, but study was not long-term.
Also concluded, consistent with other studies, was that triglycerides, high-density lipoprotein (HDL), blood pressure, and measures of insulin resistance differences were either insignificant or more favorable with very-low-carbohydrate intake. This goes against the common assumption that low-carbohydrate diets with high-fat content increase cardiovascular risk. However, with recent trials, higher LDL (the undesirable type) levels have been seen with low-carbohydrate vs. low-fat diets. Could quality of our carbohydrates today account for some of these results?
In this study, the Ornish (very low-fat), Weight Watchers High-carbohydrate, and New Glucose Revolution programs were the top three for averting heart disease based on study criteria for evaluation. Considerable focus in these plans is on fruits and vegetables.
Another study3 compared how three healthy diets affected risk for heart disease. They used a carbohydrate-rich diet similar to DASH (15% protein), a higher protein (25%) plan, and a higher unsaturated fat (15% protein) which would be close to the Mediterranean diet.
Although all three plans showed favorable results for coronary heart disease risk, blood TG levels were lowered only in the high-protein and high-fat diets. This would be expected as TG readings are affected by starch/sugar, particularly processed products. Unfortunately, the majority of the carbohydrate eaten today falls in this category and contains little nutrients.
Another review2 looked at studies on soy protein as related to LDL. As always, contradictory study results did not lead to a definite answer. This could partly be blamed on different forms of soy utilized and inclusion of isoflavonones. In 2006, the American Heart Association concluded that, although soy was not particularly helpful in lowering lipid levels, it could be an excellent source of vegetable protein to reduce saturated fat in the diet.
Common Sense and Heart Risks
All studies have limitations, usually regarding factors not accounted for, human miscalculations/actions, or not long-term. Listen to your body and learn what adversely affects how you feel. Basic advice most experts agree on still holds true and will give you the best chance for living an overall healthy life:
1. Eat your vegetables and fruits (see Food Guide Pyramid).
2. Limit saturated and trans fat.
3. Limit processed and salty foods (use whole grains).
4. Move your body!
Bibliography
1. Yunsheng MA, Pagoto SL; Griffith JA , Merriam PA, Ockene IS, Hafner AR, Olendzki CO. "A Dietary Quality Comparison of Popular Weight-Loss Plans". J Am Diet Assoc. 2007;107:1786-1791
2. Van Horn L, McCoil, M, Kris-Etherton PM, Burke F, Carson JAS, Champagne CM, Karmally W, Sikand, G. "The Evidence for Dietary Prevention and Treatment of Cardiovascular Disease". J Am Diet Assoc. 2008;108:287-324
3. Swain JF, McCarron PB, Hamilton EF, Sacks FM, Appel LJ. "Characteristics of the Diet Patterns Tested in the Optimal Macronutrient intake Trial to Prevent Heart Disease (OmniHeart): Options for a Heart-Healthy Diet." J Am Diet Assoc. 2008;108:257-265
