Even a marginal deficiency in B-vitamins such as thiamin, riboflavin, vitamin B-6, B-12 and folate may inhibit the body's ability to repair itself, operate efficiently, and fight disease.  These micronutrients are essential for the production and repair of cells.  A deficiency may lead to poor athletic performance and a decreased ability to repair and build muscle.  

The stresses on the body's energy producing pathways during exercise, the changes in the body's tissues resulting from training, and increase in the loss of nutrients needed to repair and maintain higher levels of lean tissue mass present in some athletes and individuals may all affect an individuals B-vitamin requirements, said Monroe.

Athletes generally require more than the current national B-vitamin recommendations for active individuals. 

Be sure to enjoy a variety of foods such as whole and enriched grains, dark green vegetables, nuts, and many animal and dairy products.  Do not restrict your calories or limit food groups such as dairy or milk and take a multivitamin or mineral supplement.