I am currently underweight, my nails have a yellow color could it be a deficiency of something. what supplements can i take to help me gain weight?

Doctor can check: If one is truly underweight (based on height, family background, and body type), a Dr. can evaluate for a hormonal, digestive, or other disorder. If no medical cause is found, then one can add weight by eating more calories of nutritious foods. If known vitamin deficiencies, can take more supplements. Proteins: egg white, chicken breast, salmon... Better fats: olive oil, peanuts, almonds, tofu...

Vit Deficiency: One of the most common causes of yellow nails is a fungal infection. In rare cases, yellow nails can indicate a more serious condition such as severe thyroid disease, lung disease, diabetes or psoriasis. Vitamin B12 and folate play a role in red blood cell production and oxygen transportation to nail cells. Def. can result in discoloration of your nails.( B12 def=Blue Nails). Fe def.=Spoon nail