By Cliff Harvey PhD

Unless you’ve been living under a rock for the last twenty or more years, you’ll already know the importance of quality protein for muscle building, recovery, satiety, and mood improvements.

But you may not realise that protein is also important to preserve immunity, especially if you’re an athlete, or you’re working (or playing!) hard. In fact, one of the key aspects of over-stress, overtraining, and chronic fatigue is an increased susceptibility to infection.

A deficiency in protein is rare in the modern world. But when we consider that the recommended daily intake for protein is a woefully low 0.8 g per kilo of body weight per day and that levels of 2 x this amount or more are indicated for improved performance and body composition, higher protein intake may encourage better regulation of immunity and inflammation. 1

Some specific amino acids (AAs - the building blocks of protein) have shown specific benefits. Glutamine is the most abundant amino acid in human muscle tissue. It is likely to reduce the incidence of infections and improve immunity.2-5 Glutamine levels are correlated with overtraining in athletes, and plasma glutamine levels don’t rise in athletes with overtraining syndrome (OTS) over a training cycle.6 Furthermore, athletes suffering from OTS appear to maintain low plasma glutamine levels for months or even years.7 

So, protein, along with helping you to maintain muscle, lose fat, and improve satiety, could also help you to stay well over the winter and when you’re training and working hard.

Action points:

  1. Make the ‘base’ of every meal a quality protein (like meat, fish, free-range chicken or eggs, sprouted lentils or a good quality protein powder)

  2. Take a protein drink after training to help bolster protein and glutamine intake and enhance recovery

  3. Eat at least 1.2 g of protein per kilo of body weight per day. For an average woman, for example, this equates to around 25 g of protein per meal, over three meals (or a little over 100 g of chicken or fish, or 2 scoops of Clean Lean Protein)


Clean Lean Protein contains up to 90% protein with almost zero carbs and sugar! It also has a high glutamine/glutamic acid content to help preserve immunity.




  1. Lesourd BM, Mazari L. Immune responses during recovery from protein-energy malnutrition. Clinical Nutrition. 1997;16, Supplement 1:37-46.
  2. Castell LM, Poortmans JR, Newsholme EA. Does glutamine have a role in reducing infections in athletes? Eur J Appl Physiol Occup Physiol. 1996;73(5):488-90.
  3. Castell LM, Newsholme EA. The effects of oral glutamine supplementation on athletes after prolonged, exhaustive exercise. Nutrition. 1997;13(7-8):738-42.
  4. Castell LM, Newsholme EA. Glutamine and the effects of exhaustive exercise upon the immune response. Canadian journal of physiology and pharmacology. 1998;76(5):524-32.
  5. Castell LM. Can glutamine modify the apparent immunodepression observed after prolonged, exhaustive exercise? Nutrition. 2002;18(5):371-5.
  6. Mackinnon LT, Hooper SL. Plasma glutamine and upper respiratory tract infection during intensified training in swimmers. Med Sci Sports Exerc. 1996;28(3):285-90.
  7. Rowbottom DG, Keast D, Morton AR. The emerging role of glutamine as an indicator of exercise stress and overtraining. Sports medicine (Auckland, NZ). 1996;21(2):80-97.


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