DIETARY PROTEIN AND EXERCISE: EVERYTHING YOU NEED TO KNOW.

‘Are you taking protein?’ is probably one of the most ironic questions new gym-goers ask when trying to figure out the world of exercise and healthy eating. You will hear a variety of answers depending on who you ask, ranging from “You need to eat six meals per day to stimulate muscle growth” to “Don’t take any protein supplements, they are bad for you”. This article aims to break down all thing’s protein; it loosely follows on from a previous article titled Understanding protein powder: safety, dosages, uses. A comprehensive guide to the dietary supplement.

Recommended protein intake is most certainly a controversial topic and one which has experienced considerable change in recent years. Currently, the recommended dietary allowance (RDA) for protein intake varies based on the individual’s physical activity level. As an individual’s physical activity increases so should their dietary intake; this is due to increased rates of amino acid/protein metabolisation during exercise (1) and damage to muscle tissue caused by exercise (2). Here are the current daily recommended ranges according to the International Olympic Committee (IOC) and the International Society of Sports Nutritionists (ISSN) (3).

• General population – 0.8-1.0g/kg body weight
• Physically active individual –1.0-1.5g/kg body weight
• Strength/resistance training individual – 1.5-2.0 g/kg body weight

Protein recommendations are based on measurement of nitrogen balance and utilisation of amino acid tracers. Nitrogen is the fundamental component of amino acids, which are considered the building blocks of protein (4). Nitrogen balance measurement involves tracking the total amount of nitrogen which is consumed vs the amount which is excreted; when an individual is in nitrogen balance they are considered to be consuming and excreting an equal amount of nitrogen, therefore their dietary intake meets nutritional requirements (5).

One of the common things you’ll hear in the media is that high protein consumption causes kidney failure, reportedly due to the increased strain placed on the glomerular pressure and filtration systems (6). The research which cited these issues was conducted in individuals already with renal disease, and the dots were connected to healthy individuals. Significant research has been done into this area with healthy individuals since nothing has been proven (7, 8, 9, 10).

Another commonly held belief is that high protein consumption affects calcium retention, which could predispose an individual to osteoporosis. This again has been extrapolated from studies with small sample sizes and methodological errors. Recent research has shown that the phosphate content of foods is protective against bone resorption (11).

Another topic which gains a lot of attention around protein intake is timing, specifically for exercising individuals who are performance or body composition focused. It is agreed that protein timing is essential for recovery, inducing hypertrophy, glycogen resynthesis, and perhaps maintenance of proper immune function (12).

This article’s aim is not to go into a detailed analysis of pre, intra, post-workout protein timing and amounts - that would be another article altogether!

The branched-chain amino acids (BCAAs) are three of the nine essential amino acids, specifically leucine, isoleucine, and valine. A significant body of research has stated the benefits of BCAAs on muscle protein synthesis (13), which has led to a range of BCAA supplements becoming popular.

The benefits and applicability of a BCAA supplement depend on an individual’s exercise habits and dietary patterns, along with other factors. For individuals consuming a low protein diet, BCAA supplementation can prove to be beneficial in promoting muscle retention and growth; this supplementation can be either during or after exercise (14). However, for individuals with an already high dietary protein intake (>1.5 g/kg/day) supplementation has been shown to be ineffective due to an already high BCAA content from whole food sources (15).