Protein intake and its impact on overall health and wellbeing - what does the literature say?
I was asked yesterday to debunk all of the 'broscience' and 'gymrat' info about protein intake...so here goes...
Protein is an essential macronutrient required by the human body for various vital functions, including tissue repair, muscle building, hormone production, and immune system regulation. It is necessary to consume sufficient amounts of protein through your diet to maintain optimal health and wellbeing.
Several studies have investigated the link between protein intake and health outcomes, including weight management, muscle strength and mass, bone health, and cardiovascular health. The current scientific evidence on protein intake and its impact on health and wellbeing is very robust.
Protein is known to increase feelings of fullness, thereby reducing the intake of calories and helping in weight management. A study conducted on overweight adults showed that a high-protein diet led to greater weight loss and fat loss than a low-protein diet with similar caloric intake1. Similarly, in another study, increasing the proportion of protein in the diet from 15% to 30% of total calories led to greater weight loss and fat loss in overweight individuals2.
Muscle Strength and Mass
Protein plays a crucial role in building and repairing muscle tissue. A higher protein intake, combined with resistance training, can lead to increased muscle strength and mass. In a study of older adults, consuming 1.2 grams of protein per kilogram of body weight per day led to increased muscle strength and mass after 12 weeks of resistance training3.
Protein is a crucial component of bone tissue and plays a vital role in maintaining bone health. Studies have shown that consuming sufficient protein can improve bone density and reduce the risk of osteoporosis, a condition characterized by weak and brittle bones. In a study of postmenopausal women, a higher protein intake was associated with better bone density and a lower risk of fractures.
Recent studies have investigated the link between protein intake and cardiovascular health. Some evidence suggests that a higher protein intake may help in reducing blood pressure and improving cholesterol levels, thereby reducing the risk of heart disease. However, more research is needed to establish a clear link between protein intake and cardiovascular health.
As you can see from the science, protein intake plays a vital role in maintaining optimal health and wellbeing. Consuming sufficient protein through your diet can help in weight management, building and repairing muscle tissue, improving bone health, and reducing the risk of osteoporosis. While some evidence suggests that a higher protein intake may improve cardiovascular health, more research is needed in this area.
But how much do I need...well it does depend upon your gender, size and goals, but I recommend that individuals consume at the very least 0.8 grams of protein per kg of body weight per day to maintain optimal health and wellbeing.
Leidy HJ, Carnell NS, Mattes RD, Campbell WW. Higher protein intake preserves lean mass and satiety with weight loss in pre-obese and obese women. Obesity (Silver Spring). 2007 Feb;15(2):421-9. doi: 10.1038/oby.2007.531. PMID: 17299116.
Wycherley TP, Moran LJ, Clifton PM, Noakes M, Brinkworth GD. Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials. Am J Clin Nutr. 2012 Dec;96(6):1281-98. doi: 10.3945/ajcn.112.044321. Epub 2012 Oct 24. PMID: 23097268.
Muscle Strength and Mass:
Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018 Mar;52(6):376-384. doi: 10.1136/bjsports-2017-097608. Epub 2017 Jul 11. PMID: 28698222.
Hannan MT, Tucker KL, Dawson-Hughes B, Cupples LA, Felson DT, Kiel DP. Effect of dietary protein on bone loss in elderly men and women: the Framingham Osteoporosis Study. J Bone Miner Res. 2000 Aug;15(8):2504-12. doi: 10.1359/jbmr.2000.15.8.2504. PMID: 10934641.
Kerstetter JE, O'Brien KO, Insogna KL. Dietary protein affects intestinal calcium absorption. Am J Clin Nutr. 1998 Dec;68(6):859-65. doi: 10.1093/ajcn/68.6.859. PMID: 9848512.
Rebholz CM, Friedman EE, Powers LJ, et al. Dietary Protein Intake and Blood Pressure: A Systematic Review of Randomized Controlled Trials. Hypertension. 2019 Apr;73(4):e19-e32. doi: 10.1161/HYPERTENSIONAHA.118.11958. PMID: 30852915.
Sacks FM, Lichtenstein AH, Wu JHY, et al. Dietary fats and cardiovascular disease: a presidential advisory from the American Heart Association. Circulation. 2017 Jul 18;136(3):e1-e23. doi: 10.1161/CIR.0000000000000510. Epub 2017 Jun 15. PMID: 28620111.