Muscle weakness can result from muscle injuries, genetic disorders, nervous or musculoskeletal system diseases or vitamin deficiencies. Along with exercise, damaged muscles rely on vitamins for restoration and healing. While most people get their recommended daily vitamin intake from the foods they eat, those with damaged muscles may need supplemental assistance.
Vitamin D assists the body with calcium absorption, resulting in strong bones and muscles. Common sources of vitamin D include sunlight, supplements and foods such as tuna, salmon, fortified milk, cheese and eggs. Vitamin D deficiency can lead to muscle and bone-weakening disorders; however, toxic levels of vitamin D can also cause weakness. The US-based Food and Nutrition Board recommends 200 IU of daily vitamin D intake from birth to age 50, 400 IU for people 51 to 70 years old, and 600 IU for those 71 and older.
Vitamins C and E
A study presented at the Gerontological Society of America's yearly meeting in November 2009 showed the link between muscle strength and vitamins rich in antioxidants, such as vitamin C and vitamin E. University of Pittsburgh researcher and study contributor, Dr. Anne Newman noted that muscle improvement in participants could have been an indication of an already healthy diet. Oregon State University’s Linus Pauling Institute further supports the benefits of vitamins C and E on muscles degenerated by oxidative stress. The institute found that patients recovering from anterior cruciate ligament surgery reduced inflammation and improved leg muscle strength within three months of taking antioxidant-rich vitamins. Foods abundant in vitamins C and E include fruits, leafy green vegetables, nuts and seeds.
Found in foods such as whole-grain breads, pasta, rice, beans and nuts, vitamin B1 — thiamin — is essential to metabolic and muscular activity. Thiamin is a water-soluble vitamin and dissolves from the body daily through urination. This continuous dissolution can lead to B1 deficiency. According to the Linus Pauling Institute, thiamin deficiency can cause a disorder known as dry beriberi, characterized by atypical reflexes, muscle weakness and muscle pain. The institute, in accordance with the Food and Nutrition Board, recommends a daily thiamin intake of 1.1mg for adult females and 1.2mg for adult males.