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Nutrition: Whey up the evidenceNovember 14, 2017
Protein supplements for athletes come in many forms but do you really need them? Anita Bean explains
Protein supplements can be broadly divided into three main categories: protein powders (the kind you mix with milk or water into a shake); ready-to-drink shakes; and high protein bars.
They may contain whey protein, casein, egg, soya or other non-dairy sources such as pea, hemp or brown rice protein – or a mixture of all of these.
What do they do?
The supplements provide a concentrated source of protein to supplement your usual intake.
Whey protein is derived from milk and contains high levels of the essential amino acids, which are readily digested, absorbed and retained by the body for muscle repair. Whey protein may also enhance immune function.
Casein, also derived from milk, provides a slower-digested protein as well as high levels of amino acids.
Soy protein is less widely used in supplements but is a good option for vegans and people with high cholesterol levels – 25g of soya protein daily can help to reduce cholesterol levels. Other non-dairy proteins such as pea, brown rice and hemp are often combined so they provide the full range of essential amino acids.
What’s the evidence?
Studies have shown that either a casein or whey supplement immediately after resistance training raises blood levels of amino acids and promotes protein synthesis.
Male volunteers who took 1.2g per kg of their bodyweight per day of whey protein during six weeks of resistance training achieved greater muscle mass and strength gains compared with those who took a placebo, found a 2006 study but others have reported no or minimal effects.
In one trial, those consuming 20g of whey supplement before and after resistance sessions had greater increases in muscle mass and strength over 10 weeks compared with those consuming a placebo. And another research paper showed that when athletes consumed whey immediately before and after a training session, they could perform more reps and lift heavier weights 24 hours and 48 hours after the workout compared with those who had a placebo.
It’s not all about whey
It’s important to point out that consuming any high-quality protein source immediately after a weights or strength sessions will help to promote muscle repair and growth.
Compared with casein or soy, whey supplements may be a better option in the immediate post-training period as whey is absorbed quicker, but there is no strong evidence that it results in greater muscle growth over 24 hours.
Whey can also help to boost immunity and researchers found that those athletes who consumed it following a 40km cycling time trial experienced a smaller drop in glutathione levels, a substance in the body linked to lowered immunity.
So, do you need protein supplements?
In studies where athletes were already consuming adequate amounts of protein in the diet, taking an additional source in the form of a supplement before and after training made absolutely no difference to their muscle synthesis or strength.
It is undisputed that resistance training increases muscle protein turnover and therefore the daily protein requirement. But it remains controversial whether supplements are necessary to increase muscle mass or strength or whether you can get sufficient protein from your food.
The American College of Sports Medicine (ACSM) advise that protein requirements can be met from the diet alone without the use of supplements.
Where else to get your protein
Foods such as milk, eggs, meat, poultry and fish all supply eight essential amino acids in amounts closely matched to the body’s requirements and are also naturally high in the important amino acid leucine.
If you’re already eating enough protein (1.2 to 2.0g per kg of your body weight per day is required) and getting around 20-25g protein per meal, then an additional protein from supplements is unlikely to produce further gains in muscle mass, strength or performance. Perhaps the main benefit of protein supplements and the best argued case for taking them is their convenience.
Any side effects?
Any excessive intake of protein, whether from food or supplements, is not harmful but offers no health or performance advantage. Concerns about excess protein harming the liver and kidneys or causing calcium loss from the bones have been disproved.
» Anita Bean is an award-winning registered sports nutritionist who is author of The Complete Guide to Sports Nutrition (Bloomsbury, £18.99)