Clinically proven health benefits of whey protein

You’ve probably heard that whey protein is good for you. Whey protein is the liquid fraction of whey that separates from milk during the cheese-making process. It is a high-quality protein replete with all the essential amino acids. It is also highly digestible, with quicker gut absorption compared with other proteins. These enviable qualities make whey an excellent source of dietary protein.

Three iterations of whey exist: whey protein concentrate, whey protein isolate, and whey protein hydrolysate. Of these, whey protein concentrate is the most popular and cheapest. It is commonly used by body builders and athletes to boost protein intake and gain muscle.

The effects of whey on the body have been studied, with mixed results. Nevertheless, let’s take a closer look at five studies in which researchers have demonstrated specific health benefits of whey.

Muscle growth

In a low-power study that examined the acute effects of whey or soy (both rapidly absorbed) vs casein (slowly absorbed) on muscle protein synthesis (MPS) in healthy young men, researchers discovered the intake of whey protein hydrolysate triggered MPS to a greater degree compared with casein—both at rest and post-resistance exercise. Moreover, when compared with soy, whey triggered a greater increase in MPS after resistance exercise.

In the study, participants completed repetitions of unilateral leg resistance exercise followed by the consumption of a drink consisting of equal amounts of essential amino acids (10 g) as either whey hydrolysate, micellar casein, or soy protein isolate. MPS and other variables were measured using blood tests.

“Our results suggest that the type of protein consumed is a modulating factor in determining postprandial resting and post-exercise muscle anabolism in young healthy men, both at rest and after resistance exercise. Moreover, this effect may be related to the leucine content of the protein consumed and how quickly it is digested,” concluded the authors.

Of note, the ingestion of whey protein yielded a larger increase in blood essential amino acids, branched-chain amino acids, and leucine concentrations compared with casein and soy.

Hypertension

According to some research, dairy whey protein may be the main factor underlying the health benefits of increased dairy consumption, including positive effects on blood pressure and heart health.

In a relatively low-power study that assessed the effects of whey protein supplementation vs control supplementation on blood pressure, vascular function, and inflammatory markers in overweight or obese individuals (mean BMI: 31.3 kg/m²), participants were randomized to receive either whey protein, casein, or glucose supplementation (ie, control) for 12 weeks.

Systolic blood pressure levels among participants significantly decreased at week 6 in the whey and casein groups, as well as at week 12. Diastolic blood pressure levels also decreased among individuals in the whey and casein groups at week 12 vs the control group. Furthermore, the augmentation index—a measure of systemic arterial stiffness taken from the ascending aortic pressure waveform—was reduced at 12 weeks in the whey group vs the casein and control groups.

No significant changes in inflammatory markers were observed. The researchers concluded that whey protein may improve blood pressure and vascular function in overweight and obese individuals.

Type 2 diabetes

Previous researchers have shown that whey protein boasts insulinotropic events and could decrease postprandial glycemia in healthy study participants. Apparently, this effect also extends to those with diabetes, according to the results of a low-powered study that examined whether meals with a high glycemic index plus whey protein could enhance glucose control in participants with type 2 diabetes.

In the study, participants ate high-glycemic index breakfasts (white bread) and subsequent high-glycemic index lunches (mashed potatoes with meatballs). These meals were supplemented with whey on one day, with whey exchanged for lean ham and lactose on another day. Postprandial venous blood samples were obtained to determine blood glucose, serum insulin, glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide 1 (GLP-1) concentrations.

The investigators found that insulin responses increased after both breakfast (31%) and lunch (57%) when whey was incorporated into the meal vs when it wasn’t. Following lunch, blood glucose responses significantly decreased with whey ingestion. Postprandial GIP responses were heightened after whey ingestion. However, no differences were observed in GLP-1 between the reference and test meals.

“It can be concluded that the addition of whey to meals with rapidly digested and absorbed carbohydrates stimulates insulin release and reduces postprandial blood glucose excursion after a lunch meal consisting of mashed potatoes and meatballs in type 2 diabetic subjects,” wrote the authors.

Inflammatory bowel disease

Increased intestinal permeability (IP) may play a role in the activity and relapse of Crohn disease (CD). Furthermore, glutamine may improve IP.

In a low-power, randomized, controlled trial, participants in a remission phase from CD with abnormal IP were randomized to receive either oral glutamine (glutamine group) or whey protein at 0.5 g/kg ideal body weight/day (active control group) for 2 months. The researchers analyzed the lactulose mannitol excretion ratio in urine, and morphometry was performed by computerized image analysis system. They found that IP and morphology were significantly improved in both study groups.

According to the authors:

“Increased IP is a common feature in about 30%–65% of patients with CD. IP has been implicated in the etiopathogenesis of CD, as the alterations in IP are seen in 25% of healthy first-degree relatives of CD, who may develop CD eventually. Abnormal IP has been associated with early relapse with a sevenfold increase in the relapse rates in patients with increased IP compared to normal IP. Abnormal IP also precedes clinical flare-ups; hence, it is suggested as a marker of impending relapse. Besides this, the magnitude of alteration in IP also correlates with the activity of the disease, where improvement in the disease activity corresponds with improvement in IP after therapy. Thus maintenance of normal IP may have a therapeutic benefit on the natural course of the disease.”

Inflammation

In a meta-analysis of nine randomized clinical trials, researchers noted a small but ultimately insignificant drop in C-reactive protein (CRP) levels—markers of inflammation—secondary to daily whey supplementation of < 20 g/day. However, they did observe a significant reduction in CRP levels among participants supplemented with high doses of whey protein ( ≥ 20 g/day of whey) and in those with high CRP levels ( ≥ 3 mg/L) at baseline.

“Although we successfully identified baseline CRP concentration as a potential effect modifier and major contributor to the overall between-study variation in meta-regression analysis, our results should be interpreted with caution because of the evidence of heterogeneity,” concluded the investigators.

Before you geek out on whey, keep in mind that excessive consumption may lead to nausea, pain, bloating, cramping, flatulence, and diarrhea. Plus, your body can use only so much protein. Moderate consumption is usually well tolerated, but those who are lactose intolerant may benefit from whey protein hydrolysate or isolate vs concentrate.