Protein is essential for rebuilding muscles that have been broken down during exercise, and marathoners routinely tear down muscle fibers during training efforts.

The recommended daily allowance of protein for average men and women is between 46 and 56 grams per day. However, athletes often have higher requirements, so it’s important to talk with your doctor or dietician to determine your needs. Endurance athletes need about .53 to .72 grams of daily protein per pound of body weight. Post-exercise is a great time to give your body a shot of whey protein.

The omega-3 fatty acids in fish oil can help reduce muscle soreness and increase lean body mass — two goals common to most distance runners. These fatty acids are also required to create healthy cell walls and improve the function of the immune and nervous systems. Registered dietician Cassandra Forsythe suggests choosing fish oil supplements that contain at least 500 combined milligrams of DHA and EPA, the active omega-3 compounds.

Calcium is important for avoiding stress fractures from the impact of running, but without adequate vitamin D intake, calcium cannot be properly absorbed. Vitamin D is only present in a few foods, and the body is only able to manufacture it when exposed to sunlight. For many, indoor training and sunscreen use minimizes the body’s opportunity to create the nutrient. A deficiency in Vitamin D can increase the risk of some cancers and hinder athletic performance. If your doctor indicates your Vitamin D levels are low, Forsythe suggests supplementing with 1,000 international units daily.

One of the most common complaints among distance runners is joint pain. The high-impact nature of running can give your joints a beating, no matter how great your shoes or form. Supplementing with glucosamine and chondroitin each day can help your body regenerate cartilage that’s been worn down during training. According to the Council for Responsible Nutrition, the most commonly recommended daily dosages are 1,500 milligrams of glucosamine and 1,200 milligrams of chondroitin. This supplement may also reduce cartilage breakdown and produce an anti-inflammatory effect to aid in recovery, says sports nutritionist Ross Edgely.