Lecithin

• The magazine Flex strongly urges bodybuilders to take lecithin supplements. Because lecithin plays an important role in the digestion of fats and the reduction of cholesterol levels, it can help improve your overall lipoprotein profile. Lecithin also contains choline, an essential nutrient depleted during a long or intense workout. Flex recommends bodybuilders consume four or more tablespoons of granular lecithin, which can be added to smoothies, cereal or salads. Flex recommends supplementation because most lecithin-rich foods are either high in saturated fat or highly processed.
  
  

Magnesium

• Muscles need magnesium to properly contract, making adequate intake of this nutrient crucial for developing power. Unfortunately, many athletes have marginal deficiencies of magnesium, which could hinder performance and muscle growth. Muscle & Fitness magazine recommends 250-450 mg of magnesium every day in the form of magnesium succinate or magnesium aspartate. Food sources include leafy greens, salmon, broccoli, nuts, seeds and beans.
  
  

Glutamine

• The amino acid glutamine helps pull water and glycogen into muscle cells. According to Muscle & Fitness, this means "size, baby!" Glutamine also helps ensure that amino acids don't abandon muscle growth for some other physiological task. In addition to its bodybuilding functions, glutamine also boosts immunity, which could mean you'll be in the gym instead of stuck home in bed. Muscle & Fitness recommends five grams in the morning and another five after your workout.
  
  

Potassium

• Intense physical activity and excessive fluid loss, from sweating for example, can deplete potassium levels. Potassium plays an important role in muscle contraction and nerve transmission. It also helps the body maintain fluid balance and utilize carbohydrates and protein for energy. Potassium deficiency results in muscle weakness and fatigue. The best sources of potassium are potatoes, bananas, broccoli, mushrooms, avocado, kale, milk, nuts, green beans, tofu, tomatoes, fish, celery and blackstrap molasses.
  
  

Vitamin D

• Vitamin D plays an important role in muscle function and in achieving gains in physical strength, according to research reported in Flex. Vitamin D deficiency is one of the most common nutrient deficiencies among Americans. Because many bodybuilders avoid dairy products (which are usually vitamin D fortified), they may be at increased risk. The best source of vitamin D is the sun, but many experts are reluctant to recommend sun exposure because of the increased risk of skin cancer this solution poses. Dietary sources of vitamin D include sardines and foods commonly fortified with this vitamin, such as milk, juice and cereal.