Whey-casein protein blends combine the fast- and slow-digesting properties of whey and casein protein powder.

With a whey-casein blend, you get the best of both worlds: a spike in muscle protein synthesis from the rapidly-absorbed whey and a prolonged decrease in muscle breakdown from the slowly-absorbed casein (20).

In one study, 16 men at rest drank 20 grams of whey protein blend or 20 grams of whey-casein protein blend (21).

The researchers took muscle samples from the men two hours before and several hours after consumption and found no difference between the two groups in muscle protein synthesis, suggesting the blend is just as effective as whey protein when resting.

However, it’s unclear if protein blends are as effective as whey protein for increasing muscle protein synthesis around exercise.

In a ten-week study, 68 men received whey-casein protein blend or an equal amount of casein protein while undergoing lower-body resistance training (22).

Results showed that those consuming the whey-casein blend experienced less muscle fatigue compared to the casein group. Still, no differences in muscle size or strength were detected between the two groups.

The percentage of protein from whey and casein varies between products on the market. More often than not, the whey-casein blends contain more whey than casein.

For example, this whey-casein blend by Dymatize Nutrition has 75% whey and 25% casein protein per scoop, whereas this product by EAS Sports Nutrition does not list the percentage.