Does whey protein supplementation during resistance exercise have additional benefits for decreasing hepatic fat content?

BACKGROUND

Exercise and diet have positive effects on hepatic fat reduction, and protein supplementation is known to lower hepatic fat accumulation. However, the effect of a combination of exercise and whey protein supplementation (WPS) on hepatic fat content (HFC) is unknown.

METHODS

We investigated the effect of WPS on HFC during resistance exercise and diet control intervention for four weeks. A total of 34 sedentary males participated and were randomly assigned to two groups: a protein supplement group (PSG, n = 18) and a control group (CG, n = 16). The PSG took 60 g of WPS per day, and the CG took 60 g of an isocaloric placebo per day. All participants were fed a calorie-controlled diet throughout the study period, with their daily caloric intake determined by their resting metabolic rate and physical activity level. Both groups performed resistance exercises supervised by experts at 60-70% of their maximum efforts for 60 min/day, 6 days/week for 4 weeks. HFC was assessed using the controlled attenuation parameter (CAP) after an 8 h fast, at pre-, mid-, and post-intervention. Liver enzymes and lipid profile were also analyzed after an 8 h fast and pre- and post-intervention.

RESULTS

The CAP was significantly reduced after 4 weeks of intervention in both groups (PSG, p < .001; CG, p = .002). However, there was no significant interaction between the group and changes in CAP. Interestingly, when comparing the pre- and mid-tests, both groups also had significantly reduced CAP (PSG, p = .027; CG, p = .028), but there was a significant difference in the amount of change in CAP between the two groups (PSG, -47.2 ± 25.4 dB/m; CG, -19.5 ± 15.1 dB/m; p = .042). For liver enzymes, there was a significant interaction between the two groups and a change in aspartate transaminase (AST) (p = .038). However, alanine aminotransferase (ALT) levels were significantly decreased only in the PSG group (p = .002). In lipids, both groups showed significantly decreased total cholesterol (p < .001) and low-density lipoprotein cholesterol (p < .001) after the intervention.

CONCLUSION

Our data showed that WPS may not enhance the overall effects of resistance exercise on HFC and lipid profiles. However, in part, WPS may have a beneficial effect on liver enzymatic changes and rapid response to resistance exercise-induced HFC reduction.

Rapid Detection of Adulterants in Whey Protein Supplement by Raman Spectroscopy Combined with Multivariate Analysis

The growing demand for whey protein supplements has made them the target of adulteration with cheap substances. Therefore, Raman spectroscopy in tandem with chemometrics was proposed to simultaneously detect and quantify three common adulterants (creatine, l-glutamine and taurine) in whey protein concentrate (WPC) powder. Soft independent modeling class analogy (SIMCA) and partial least squares discriminant analysis (PLS-DA) models were built based on two spectral regions (400-1800 cm-1 and 500-1100 cm-1) to classify different types of adulterated samples. The most effective was the SIMCA model in 500-1100 cm-1 with an accuracy of 96.9% and an error rate of 5%. Partial least squares regression (PLSR) models for each adulterant were developed using two different Raman spectral ranges (400-1800 cm-1 and selected specific region) and data pretreatment methods. The determination coefficients (R2) of all models were higher than 0.96. PLSR models based on typical Raman regions (500-1100 cm-1 for creatine and taurine, the combination of range 800-1000 cm-1 and 1300-1500 cm-1 for glutamine) were superior to models in the full spectrum. The lowest root mean squared error of prediction (RMSEP) was 0.21%, 0.33%, 0.42% for creatine, taurine and glutamine, and the corresponding limit of detection (LOD) values for them were 0.53%, 0.71% and 1.13%, respectively. This proves that Raman spectroscopy with the help of multivariate approaches is a powerful method to detect adulterants in WPC.