Vitamin B12 & Fingernails

Vitamin B12 is vital in protein and DNA synthesis, and it also has the distinction of being the only water-soluble vitamin that your body stores. Because your body typically saves enough vitamin B12 to last you years, vitamin B12 deficiency is rare. Fingernails are adversely affected by deficient vitamin B12 levels because of the vitamin's role in helping supply the methyl groups needed to synthesize protein. Since the keratin in fingernails is protein, deficient vitamin B12 levels adversely affect keratin production. According to a case study in a 1972 issue of the "Canadian Medical Association Journal", insufficient levels of vitamin B12 will cause your nails to become brittle.

Vitamin B12 Dose

Taking the recommended dose of vitamin B12 will help keep your fingernails healthy. The recommended daily dose varies according to age. Newborns and infants 6 months in age need about 0.4 mcg of vitamin B12 daily, the University of Maryland Medical Center notes. Infants between 6 months to a year old need about 0.5 mcg of vitamin B12. Children between the ages of 1 and 3 need 0.9 mcg daily. Between the ages of 4 and 13, children need 1.2 mcg to 1.8 mcg of vitamin B12 each day. People over the age of 14 need about 2.4 mcg of vitamin B12. Pregnant females need 2.6 mcg per day and breastfeeding women need 2.8 mcg per day.

Vitamin B12 and Fingernail Appearance

A 1972 issue of the "Canadian Medical Association Journal" featured a case study of a man who was 68 years of age and suffered from intermittent diarrhea over a period of 25 years. Further testing showed that he was unable to properly absorb vitamin B12. As a result his vitamin B12 levels were deficient. As a result, his fingernails grew increasingly more brittle over a period of five to 10 years.

Other Signs of Poor Fingernail Health

Fingernails are made of laminated layers of keratin, a protein that grows under your cuticle. When your nails are healthy, they appear smooth and free from ridges or grooves, MayoClinic.com says. Fingernails that are discolored, or appear pitted, curled and opaque are generally not healthy. However, injury also causes your fingernails to develop white lines or spots.

Nail Hyperpigmentation

The "Archives of Dermatology" published a study in 1986 that found that hyperpigmentation of nails was directly related to vitamin B12 deficiency. The cause of the patient's vitamin B12 deficiency was induced by pernicious anemia. Pernicious anemia is a disease characterized by the lack of a substance called intrinsic factor. Intrinsic factor is required for proper absorption of vitamin B12. Once the pernicious anemia was treated, fingernail pigmentation returned to normal. This suggests that fingernail hyperpigmentation is reversible when vitamin B12 levels are restored to normal.