Protein Supplementation Part 2

Article by Tanya Mezher

Although it is recommended to meet your protein needs through dietary sources, there will be times when those needs are not met and supplementation can fill in the gaps. There are many options out there, so here is some more information on common choices. 

Which is best: whey, casein, or plant proteins? Studies have shown consumption protein after resistance exercise is effective in muscle re-building and strengthening. Two popular options are milk-based proteins, casein and whey. These are both complete proteins, meaning they contain all 9 essential amino acids, and are the main proteins found in milk. Although casein represents the majority of protein in milk, it is slower to digest, and therefore takes longer to release amino acids into the bloodstream. For this reason, whey protein is more commonly used in protein supplements and powders. Those who are lactose-intolerant may benefit from a version of whey protein powders made from whey isolatewhich is more highly processed (removing the majority of lactose) versus whey concentrate. Opting for a plant-based protein like soy, pea, or wheat can also mitigate the effects of lactose-intolerance. Current evidence shows that dairy protein supplements appear to be superior than other proteins tested, likely due to the leucine content (see more on BCAA and leucine below), digestive capabilities, and structure of dairy proteins. However, further studies are warranted to test isolated plant-based protein in comparison to dairy protein supplements. 

Leucine is an essential, branched chain amino acid, important for metabolic functions and protein synthesis. Supplementation of leucine alone appears safe in doses up to 500 mg per kg per day (i.e. 38 grams per day for a 75 kg / 165 lb individual). However, there is limited evidence of the beneficial effects of supplementation if adequate dietary protein is already being consumed.

Branch Chain Amino Acids (BCAAs) are named in reference to their chemical structure. The three branched chain amino acids include leucine, isoleucine and valine. BCAAs are essential amino acids, meaning they cannot be made in the body but must come from food. Especially good sources are animal products such as meat, poultry, fish, eggs and milk. BCAAs make up about 16% of the amino acids in muscle proteins and unlike other essential amino acids, they can be metabolized for energy during exercise. Although BCAA supplementation of up to 20 g/day appears safe without adverse effects, there is limited research and minimal evidence of improved performance for endurance activities such as running. BCAA supplements may help muscle gain and strength when combined with weight training, however because the other essential amino acids are also required for protein synthesis, it is not likely BCAA supplements alone are any more helpful than eating sufficient high quality protein foods. 

Bottom line: It is recommended that protein needs be met through dietary sources and only supplemented if adequate needs cannot be met via diet. Protein supplements such as whey, casein, or plant proteins may be indicated when adequate needs are not met through a variety of dietary sources. Dairy is proven superior over isolated plant proteins at this time, and whey is more common due to its digestibility. BCAA supplementation (of which Leucine is most popular) may be safe up to 20 g/day and only beneficial if adequate dietary intake is not met.