Journal Title (Medline/Pubmed accepted abbreviation): Br J Nutr
Page numbers: 716-723
Summary of Background and Research Design
Background:The health benefits associated with increased dairy intake may be attributable to the whey component of dairy proteins. This study evaluated the effects of whey protein supplementation on body composition, lipids, insulin, and glucose compared with casein and glucose (control) supplementation in overweight or obese individuals for 12 weeks.
Hypothesis: Whey protein is associated with the health benefits observed with increased dairy intake.
Subjects: 70 men and women with a mean age of 48.4 ± 0.86 years and a mean body mass index (BMI) of 31.3 ± 0.8 kg/m2
Experimental design:Randomized, parallel group study
Treatments and protocol:Subjects were randomized to 54 g/day of either whey protein or casein, versus an equivalent amount of glucose (control) supplementation for 12 weeks. Fasting blood samples and dual-energy X-ray absorptiometry measurements were taken.
Summary of research findings:
- Subjects supplemented with whey protein had no significant change in body composition or serum glucose at 12 weeks compared with the control or casein group
- Correspondingly, there were no differences in total energy intake among the 3 groups at baseline, 6, and 12 weeks. The only significant dietary differences were the percentages of energy from carbohydrate and protein, which would be expected based on the nature of the supplements given to the 3 groups.
- Fasting triacyglycerol (TAG) levels were significantly lower in the whey group compared with the control group at 6 weeks (P = .025) and 12 weeks (P = .035)
- There was a significant decrease in total cholesterol and low-density lipoprotein cholesterol at week 12 in the whey group compared with the casein (P = .026 and P =.045, respectively) and control groups (P < .001 and P =.003, respectively)
- Fasting insulin levels and homeostasis model assessment of insulin resistance scores were also significantly decreased in the whey group compared with the control group (P = .049 and P = .034, respectively)
Interpretation of findings/Key practice applications:
Whey protein is the component of dairy that improves fasting lipids and insulin levels in overweight and obese individuals, suggesting that it is the main component of dairy products that provides health benefits. One potential limitation of the study is that it was not clear if the physical activity levels among the 3 groups were monitored and if there were differences in this parameter. However, the lack of differences in any body composition parameters supports that physical activity levels may have been comparable among the groups.