Myths & Truths About Protein

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Once established, truisms and myths in nutrition die hard. Dietary protein intake has been subjected to many of these myths; high protein intake is considered harmful to the kidneys, is said to create an “acidic” environment in the body, and is purported to have a negative impact on bone health.

Protein Myths

A high protein intake is potentially harmful to the kidneys only if a person has a pre-existing renal condition (1). In healthy people, there is scant evidence that high protein intake, up to 3g per kilogram of bodyweight, has any negative affects on renal function. (1; 2)

Another myth about protein, particularly in natural health circles, is this idea that it is “acidic” to the body, and upsets the pH balance that the body likes to regulate tightly. Protein breakdown begins in the stomach, which is a naturally acidic environment – we need proper stomach acid production in order to properly digest proteins and food generally. Bicarbonate from the pancreas then neutralises the acidic chyme as it moves from the stomach into the small intestine. This is a normal physiological process, the acidity is neutralised in the process of digestion.

The negative impact of this so-called ‘acidic’ effect of dietary protein was traditionally said to be lowered bone mineral density; bones would secrete calcium in order to neutralise the ‘acidic’ environment, and this was supported by the fact that increased urinary calcium is noted with higher protein diets. (1)

This is also incorrect. Body stores of calcium are not negatively affected by high protein intake; in fact, protein intake promotes intestinal absorption of calcium (1; 3). It is now accepted that high protein diets positively influence bone mineral density through increased intestinal calcium absorption, stimulation of IGF-1, which promotes bone formation. (1; 3; 4)

With the myths out of the way, let’s turn our attention to a few reasons why eating a high protein diet is a good call.

Protein Truths

1: Appetite Regulation

Recently Stephan Guyenet posted his disappointment at the fact that even if the face of declining carbohydrate and sugar consumption, obesity trends are still rising.

The fact is that we need start making dietary recommendations that address why we eat, and why we overeat.

Protein is by far the most satiating of foods. Eating higher protein breakfasts controls appetite later in the day and leads to less overall calories consumed. (5; 6)

The term “hyperpalatability” has been used to describe foods with combinations of sugar, fat and salt, that play on our evolutionary hardwiring for these tastes and override our satiety mechanisms, leading to hedonic eating. (7)

Protein acts in opposition to these reward systems, and has a direct suppressing effect on the hedonic food-reward systems.

If you want to naturally control appetite, dietary protein is the most effective tool at your disposal.

2: Lean Body Mass

Why is this important?

From around age 30, metabolic rate starts to decline around 2-4% per year (8); when added to lowered activity levels, this means even if you eat the same amount as you did in your 20’s, you’ll put on weight.

The solution is to preserve your lean body mass, i.e. muscle tissue. This is why resistance training becomes so important as people age, to both preserve metabolic rate and bone density.

In elderly populations, increasing dietary protein promotes lean body mass and enhances muscular strength (9). In both young men and women, higher protein intake leads to improvements in body composition, and promotes strength and lean muscle development. (10)

3: Weight Maintenance

One of the biggest challenges we face isn’t getting people to lose weight, it’s getting people to maintain weight loss. Estimates range from anywhere up to 90% of people regain weight with interest after a weight-loss diet.

The most effective means of losing weight is losing body fat with minimal loss of lean mass (for the aforementioned metabolic benefits); higher protein diets lead to greater fat loss when carbs and fat are matched. (11)

Given that a calorie deficit is a prerequisite to weight loss, a higher protein diet will preserve lean body mass when calories are restricted. (12)

More importantly, keeping dietary protein intake high increases the likelihood of maintaining the weight once lost (13), which is the most important part of the battle.

Not only that, but the indirect consequences of weight loss from higher protein intake go beyond a smaller waistline; cardiometabolic markers like triglycerides and blood pressure all improve. (13)

4: Bone Health

Oh, the irony.

Higher protein intake reduces risks of fractures over the long-term, and increases bone mineral density (3). Protein increases intestinal calcium absorption, and directly stimulates IGF-1 bone formation activity. (1; 3; 4)

Protein becomes particular important in elderly populations, in whom it not only promotes bone mineral density, but also reduces inflammatory markers (14). Ensuring an adequate calcium intake alongside a high protein diet reduces bone loss in the elderly, and may be the best strategy for prevention of osteoporosis (3; 4)

Separating Myth From Reality

If you want something believed in nutrition, just keep repeating it over and over until it’s cemented as fact. This happens all the time, and protein has been subjected to its fair share of ‘nutritionisms.’

But if you want better body composition, easier weight loss, better weight maintenance, and preservation of lean and bone mass into your twilight years, orientating your diet around protein intake is a solid strategy.

And before everyone jumps at the assumption that this is validation of some Paleo/primal meat—orientated emphasis, check yourself. The same benefits can be obtained through consumption of adequate protein in the context of a plant-based diet.

The principle is the protein, not necessarily where or how you get it.


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References

Cuenca-Sanchez, M., Navas-Carrillo, D. and Orenes-Pinero, E. (2015). Controversies Surrounding High-Protein Diet Intake: Satiating Effect and Kidney and Bone Health. Advances in Nutrition: An International Review Journal, 6(3), pp.260-266.

Helms, E., Aragon, A. and Fitschen, P. (2014). Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr, 11(1), p.20.

Cao, J. and Nielsen, F. (2010). Acid diet (high-meat protein) effects on calcium metabolism and bone health. Current Opinion in Clinical Nutrition and Metabolic Care, 13(6), pp.698-702.

Dawson-Hughes, B. (2003). Interaction of dietary calcium and protein in bone health in humans. The Journal of Nutrition, March; 133(3), pp.852S-854S.

Rains, T., Leidy, H., Sanoshy, K., Lawless, A. and Maki, K. (2015). A randomized, controlled, crossover trial to assess the acute appetitive and metabolic effects of sausage and egg-based convenience breakfast meals in overweight premenopausal women. Nutrition Journal, 14(1), p.17.

Fallaize, R., Wilson, L., Gray, J., Morgan, L. and Griffin, B. (2012). Variation in the effects of three different breakfast meals on subjective satiety and subsequent intake of energy at lunch and evening meal. European Journal of Nutrition, 52(4), pp.1353-1359.

Rolls, E. (2010). Taste, olfactory and food texture reward processing in the brain and obesity. Int J Obes Relat Metab Disord, 35(4), pp.550-561.

Berardi JB, Andrews R (2013). The Essentials of Sport and Exercise Nutrition. 2nd Edition. Toronto: Precision Nutrition Inc.

Daly, R., O’Connell, S., Mundell, N., Grimes, C., Dunstan, D. and Nowson, C. (2014). Protein-enriched diet, with the use of lean red meat, combined with progressive resistance training enhances lean tissue mass and muscle strength and reduces circulating IL-6 concentrations in elderly women: a cluster randomized controlled trial. American Journal of Clinical Nutrition, 99(4), pp.899-910.

Antonio, J., Ellerbroek, A., Silver, T., Orris, S., Scheiner, M., Gonzalez, A. and Peacock, C. (2015). A high protein diet (3.4 g/kg/d) combined with a heavy resistance training program improves body composition in healthy trained men and women – a follow-up investigation. J Int Soc Sports Nutr, 12(1).

Soenen, S., Bonomi, A., Lemmens, S., Scholte, J., Thijssen, M., van Berkum, F. and Westerterp-Plantenga, M. (2012). Relatively high-protein or ‘low-carb’ energy-restricted diets for body weight loss and body weight maintenance?. Physiology & Behavior, 107(3), pp.374-380.

Churchward-Venne, T., Murphy, C., Longland, T. and Phillips, S. (2013). Role of protein and amino acids in promoting lean mass accretion with resistance exercise and attenuating lean mass loss during energy deficit in humans. Amino Acids, 45(2), pp.231-240.

Leidy, H., Clifton, P., Astrup, A., Wycherley, T., Westerterp-Plantenga, M., Luscombe-Marsh, N., Woods, S. and Mattes, R. (2015). The role of protein in weight loss and maintenance. American Journal of Clinical Nutrition.

Daly, R., O’Connell, S., Mundell, N., Grimes, C., Dunstan, D. and Nowson, C. (2014). Reply to AM Bernstein et al. American Journal of Clinical Nutrition, 99(6), pp.1521-1522.