Saturday, February 25, 2012

Setting the Record Straight on Protein

Of all the nutrients in our food, protein seems to be the one most besmirched by myth and misunderstanding.
Here are some of the more common fallacies made to pass off as facts:
  • You can only digest 20-30 grams of protein at each meal
  • High protein foods can cause kidney damage
  • Dietary protein increases the risk of heart disease
  • Diets high in protein could lead to bone damage

Recent studies have forced many ‘experts’ to question their long-standing beliefs about high protein foods.

Protein Digestion

Firstly, the notion that everyone (regardless of age, activity level, or weight), can digest the same amount of protein at each meal makes very little sense.
Secondly, there is evidence to the contrary to show that larger amounts of protein consumed less frequently leads to a more positive nitrogen balance. (Nitrogen balance is a way of measuring how protein is metabolized).
These studies show that even in non-exercising subjects, the body can digest and use a relatively large amount of protein (50-60 grams) when it's provided in a single meal [1].

Kidney Damage

This myth comes from incorrectly assuming that research data involving kidney disease patients also applies to healthy individuals.
While a severe low-protein diet may help patients with kidney failure, there is, however, a lack of evidence to show that protein intake above the RDA (recommended daily allowance) has any adverse effect on kidney function in healthy people.
A six-month study of overweight and obese subjects also shows that increasing the amount of protein in the diet does not have any adverse effect on several markers of kidney function [2].

Heart Disease

Researchers at Harvard Medical School examined the link between protein intake and heart disease in a group of 80,082 women. The study shows that protein from both animal and vegetable sources is linked to a lower risk of heart disease [3].
Dr. Bernard Wolfe has also shown that total cholesterol, VLDL cholesterol, LDL cholesterol and triglycerides all dropped when subjects made the switch to a high-protein diet [4].
Protein and Bone Health

Health experts have long thought that diets high in protein could lead to bone damage. But a recent series of studies by the US ‘Agricultural Research Service’ (ARS) suggest that bones aren't harmed by protein after all; they actually benefit from it, largely by aiding calcium absorption when the mineral is at low levels.

The Bottom Line

Experts who caution against high protein are usually the ones who throw caution to the winds when recommending high carbohydrate consumption to everybody (without regard for an individual’s metabolic type). With diabetes and insulin-resistance running rampant in India, its time to take a saner approach.
Different people can safely metabolize different amounts of protein, carbohydrate and fat. Find out what combination suits your body type and lifestyle best. An unbiased nutritionist (i.e. one who’s not blinded by dogma) can help.

1. [American Journal of Clinical Nutrition, 69, 1202-1208]
2. [International Journal of Obesity and Related Metabolic Disorders, 23, 1170-1177].
3. [American Journal of Clinical Nutrition, 70, 221-227].
4. [Clinical and Investigative Medicine, 22, 140-148].