As a dedicated bodybuilder and m&f reader, you’re likely well aware of the benefits of the milk proteins – whey and casein – for promoting muscle growth. But you probably know little about a closely related supplement that also offers muscle-building advantages. That supplement is colostrum, and recent studies show it can offer huge benefits to bodybuilders.

Colostrum comes from the very same udders that produce the milk you drink. The major difference is colostrum is produced only shortly before and after the cow gives birth. Essentially a form of milk that’s much higher in immune-system-enhancing compounds and anabolic agents such as insulinlike growth factor-1 (IGF-1), colostrum has also been shown to have higher levels of the hormone leptin than milk. Leptin helps keep your metabolic rate up and hunger down.

Research on the effect of colostrum in athletes shows it can help increase muscle mass and strength, as well as prevent fatigue, by buffering levels of acidity that rise during exercise. Its mass- and strength-producing effects are likely due to its high IGF-1 content, which increases during colostrum supplementation. IGF-1 is critical for instigating muscle growth, and its immunity-enhancing properties are important for bodybuilders as well as other athletes. The immune compounds it contains, namely a variety of immunoglobulins, can help aid recovery after training and prevent you from getting sick and missing training sessions.

Researchers from the University of Queensland in Australia conducted a study on highly trained cyclists to investigate the effects of colostrum on immune function and recovery. During the first five weeks, subjects took either 10 grams of colostrum or whey protein per day. During the sixth and final week, subjects performed two time trials and five consecutive days of high-intensity training. The scientists reported in a 2007 issue of the Journal of Applied Physiology that subjects who took colostrum had improved immune function and decreased symptoms of respiratory illness compared to subjects who took whey.

Enhancing your immune function can improve recovery and allow you to train harder. In fact, the same researchers reported in a 2006 study that cyclists who supplemented with colostrum bettered their cycling performance. You may not be a cyclist, but this research has definite implications for you in the gym. Enhanced cycling performance is similar to enhanced gym performance: You can get more reps with a given weight and train harder for longer. This all equates to greater muscle growth, which is the bottom line we’re all looking for.