Protein in milk has several functional properties
Protein in milk may represent a promising lifestyle intervention strategy for the prevention and management of various chronic disease including obesity, cancer, and type 2 diabetes.
Milk is a protein-rich food, we all know that. Those of you who train regularly are probably familiar with one specific type: whey proteins. Protein in milk can be divided in two major classes, with whey proteins contributing to approximately 20% of proteins in milk and caseins representing about 80% of them.
Whey protein, in particular, include different sub-types such as lactoalbumin, serum albumin, immunoglobulins, lactoferrin and proteose-peptone fractions [1]. You have probably heard of some of these proteins before, but you didn’t know they were whey proteins.
Caseins are a group of protein in milk that are classified based on Greek letters: a, b, g, and k-caseins.
Now that I have explained how proteins in milk are organized, let’s dig more into their functional properties. First of all, milk proteins are known for their positive effect on satiety, with whey proteins being potentially more satiating than caseins. Both whey and casein proteins can stimulate insulin secretion in healthy, obese, pre-diabetic and type 2 diabetes individuals.
Proteins in milk are often used as supplements by athletes who want to increase their muscle mass. Indeed, it is well known that dairy proteins can increase muscle protein synthesis in humans. Actually, I also recommend whey protein supplementation to elderly people, for the favorable influence these proteins have on bone health and sarcopenia. For the latter, a co-supplementation with the branched-chained amino acid leucine can be useful as well.
For a maximum effect on muscle protein synthesis, the timing is important. When I work with non-athlete people, I usually recommend taking protein supplements during the morning. However, in terms of nutrition for athletes, there are some other considerations that need to be done.
Indeed, the timing of protein ingestion influences protein balance. More specifically, muscle protein synthesis is enhanced when whey proteins are consumed right after an intense exercise.
It is also good to know that the co-ingestion of carbohydrate together with proteins during the recovery phase after training has many potential positive effects. The latter include a positive net protein balance, an enhanced glycogen re-synthesis in muscles, and a reduction in muscle soreness.
Speaking of other protein in milk, it is important to underline that lactoferrin has antimicrobial activities and, notably, it is able to prevent Helicobacter pilori infection. This is good news for gastric cancer prevention.
Protein in milk have several potentially positive effects. However, this is not enough to claim that milk is necessarily a healthy drink. A possible contamination with endocrine disruptors (such as PCBs and plasticizers), potential high estrogen concentrations and the negative effects associated with milk processing (which include milk homogenization, heat treatments, and others) can seriously affect milk health properties. Keep following my blog for more updates on this interesting topic!
References
- Burd, N. A. et al. (2009) ‘Exercise training and protein metabolism: influences of contraction, protein intake, and sex-based differences’, Journal of Applied Physiology, 106(5), pp. 1692–1701. doi: 10.1152/japplphysiol.91351.2008.
- Horner, K., Drummond, E. and Brennan, L. (2016) ‘Bioavailability of milk protein-derived bioactive peptides: A glycaemic management perspective’, Nutrition Research Reviews, 29(1), pp. 91–101. doi: 10.1017/S0954422416000032.
- Howarth, K. R. et al. (2009) ‘Coingestion of protein with carbohydrate during recovery from endurance exercise stimulates skeletal muscle protein synthesis in humans’, Journal of Applied Physiology, 106(4), pp. 1394–1402. doi: 10.1152/japplphysiol.90333.2008.
- Hulston, C. et al. (2010) ‘Protein ingestion increases muscle protein synthesis after, but not during, endurance exercise’, British Journal of Sports Medicine. British Association of Sport and Exercise Medicine, 44(14), pp. i6–i7. doi: 10.1136/bjsm.2010.078972.19.
- Ivy, J. L. et al. (2002) ‘Early postexercise muscle glycogen recovery is enhanced with a carbohydrate-protein supplement’, Journal of Applied Physiology, 93(4), pp. 1337–1344. doi: 10.1152/japplphysiol.00394.2002.
- Kumar, V. et al. (2009) ‘Human muscle protein synthesis and breakdown during and after exercise’, Journal of Applied Physiology, 106(6), pp. 2026–2039. doi: 10.1152/japplphysiol.91481.2008.
- Luden, N. D., Saunders, M. J. and Todd, M. K. (2007) ‘Postexercise carbohydrate-protein- antioxidant ingestion decreases plasma creatine kinase and muscle soreness.’, International journal of sport nutrition and exercise metabolism, 17(1), pp. 109–23. Available at: http://www.ncbi.nlm.nih.gov/pubmed/17460336.
- Nongonierma, A. B. and FitzGerald, R. J. (2015) ‘Bioactive properties of milk proteins in humans: A review’, Peptides. Elsevier Inc., 73(0), pp. 20–34. doi: 10.1016/j.peptides.2015.08.009.
- Rasmussen, B. B. et al. (2000) ‘An oral essential amino acid-carbohydrate supplement enhances muscle protein anabolism after resistance exercise’, Journal of Applied Physiology, 88(2), pp. 386–392. doi: 10.1152/jappl.2000.88.2.386.
[1] Proteose-peptone fractions are acid-soluble and heat-stable milk protein fraction characterized by relevant functional properties.
