10 Ways Your Body Is Telling You You’re Running Low on Key Vitamins

”Bumps on the backs of arms" Possible deficiency: Zinc and vitamin A If your arms aren't super smooth but you don't know why — and treating the bumps, a condition called keratosis pilaris, isn't working well — something could be missing from your diet. 'Many patients have these little red bumps that don't itch. I always look at their zinc and vitamin A levels,' says Small.