Whey protein benefits for overweight adults

A world-leading study by Australian researchers has found that whey protein, found in dairy foods, improved a number of health risk factors in overweight or obese adults.

Two research papers that describe the intervention trial are about to be published in two peer-reviewed journals – Obesity and the British Journal of Nutrition.

The randomised, single blind, parallel design study, conducted by Associate Professor Sebely Pal and colleagues from Curtin University, evaluated the effects of whey protein supplementation on a number of health risk factors in a group of overweight or obese adults.

The study to be published in Obesity evaluated the effects of whey protein isolate on blood pressure, vascular function and inflammatory markers compared with casein and a control (glucose) in overweight and obese adults.¹ The study to be published in the British Journal of Nutrition looked at the effects of whey protein isolate on body composition, lipids, insulin and glucose.²

All 70 participants – 60 women and 10 men – were overweight or obese, with a mean BMI of 31–32. For 12 weeks, they were randomly allocated to replace a portion of their normal diet with a package of supplement – whey protein isolate (27 g protein), sodium caseinate (27 g protein) or glucose (27 g) – twice a day (30 minutes or less before breakfast and 30 minutes or less before their evening meal). Participants also consumed one or less daily serve of dairy.^1,2

After the 12 weeks, the researchers found that there was no overall effect of supplements on body weight, BMI, waist, waist:hip ratio, total body fat, android fat, gynoid fat and lean body mass between or within groups.² However, the whey protein group showed improvements in their cholesterol levels, insulin levels, blood pressure and artery stiffness.^1,2

Supplementation with whey protein for 12 weeks decreased total cholesterol (TC) and LDL cholesterol compared with the supplementation with control and casein. TC and LDL cholesterol were decreased by 7% in the whey group compared to baseline.²

Plasma insulin levels were decreased by 11% in the whey group at week 12, compared to baseline. There was no effect of casein supplementation on any metabolic risk parameter compared with the control.²

Supplementation with whey and casein protein for 12 weeks decreased systolic blood pressure (SBP) compared to baseline (4% decrease for whey and 4.2% decrease for casein). There was no significant difference in SBP between diets at 12 weeks. Diastolic blood pressure was also decreased compared to baseline (3.3% decrease for whey).¹

Arterial stiffness, measured as Central Augmentation Index (AI), was significantly decreased by 14% from baseline in subjects who consumed the whey protein for 12 weeks. This decline was 21% greater than in the control group and 23% greater than in the casein groups (P<0.05).¹

The beneficial effects of whey proteins on serum lipids and insulin are important observations. The authors suggest that at the very least, whey protein may slow down overweight and obese adults’ progression to the metabolic syndrome, cardiovascular disease and diabetes. They suggest that collectively, whey protein has the potential to be used as an additional component in dietary plans and in functional foods aimed at the management of chronic diseases in overweight and obese individuals.^1,2

Dairy Australia dietitian Glenys Zucco said the results highlighted whey protein had important health benefits for overweight and obese adults.

"Previous research has indicated that people who consume higher amounts of dairy foods such as milk, yoghurt and cheese tend to have a lower risk of heart disease and type 2 diabetes than people who eat little or no dairy foods,³" Ms Zucco said.

"This study suggests that one of the reasons for this may be due to the bioactive proteins found in whey protein."

Whey protein makes up about 20 percent of the protein naturally present in dairy foods such as milk, yoghurt and cheese.

It has been estimated that about 30% of Australian adults have the metabolic syndrome – a combination of factors such as obesity, unhealthy cholesterol levels, high blood pressure and insulin resistance, which significantly increase the risk of cardiovascular disease and type 2 diabetes.⁴

Project leader and a key researcher at Curtin University in Western Australia, Sebely Pal said her latest results highlighted benefits of overweight and obese patients taking regular whey protein.

"The full health-giving potential of whey proteins is a growing area of research, so there is much potential for these outcomes to have a real impact on health," Dr Pal said.

References

Pal S, Ellis V. The chronic effects of whey proteins on blood pressure, vascular function, and inflammatory markers in overweight individuals. Obesity (Silver Spring). 2009 Nov 5 [Epub ahead of print].
Pal S, Ellis V, Dhaliwal S. Effects of whey protein isolate on body composition, lipids, insulin and glucose in overweight and obese individuals. Br J Nutr. 2010 Apr 9:1-8. [Epub ahead of print].
Elwood PC, Givens DI, Beswick AD, et al. The survival advantage of milk and dairy consumption: an overview of evidence from cohort studies of vascular diseases, diabetes and cancer. J Am Coll Nutr. 2008;27(6):723S-34S.
Barr ELM, Magliano DJ, Zimmet PZ, et al. AusDiab 2005. The Australian Diabetes, Obesity and Lifestyle Study. Melbourne: International Diabetes Institute; 2006.