Do Vitamin Deficiencies Cause Fingernail Ridges?

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Deficiencies in zinc, folic acid, iron and protein may cause fingernail ridges. The appearance of your nails may also indicate that you’re experiencing other health issues, like psoriasis or kidney problems.

Nutrients and Nail Health

The fingernails and toenails are made up of keratin, just like your hair. According to an interview in the Huffington Post with Jessica Krant, MD, a dermatologist and assistant clinical professor of dermatology at SUNY Downstate Medical Center in New York City, "Keratin is a protein, and healthy oils and fats are also needed to keep the skin, hair and nails moisturized and strong. A varied diet rich in vitamins, antioxidant fruits and veggies, protein and minerals is key for healthy nails and hair."

Nutritional Deficiencies and Your Nails

White streaks on your nails, rather than indented ridges, can point to other issues, including psoriasis or chronic kidney disease. However, according to the National Health Service, most small white streaks or spots on your fingernails do not indicate serious health issues.

Horizontal Ridges on Fingernails

Beau's lines are horizontal ridges on fingernails that are distinctive because they are on the surface of your nails, rather than beneath or inside your nails. According to the Mayo Clinic, Beau's lines can occur because of lack of zinc, lack of protein or malnutrition, but tend to occur when something has prevented your nail from growing during a certain period of time, like injury or illness.

These horizontal ridges on fingernails can also be caused by conditions like:

  • Diabetes
  • Peripheral vascular disease
  • Scarlet fever
  • Measles
  • Mumps
  • Pneumonia
  • Exposure to extreme cold
  • Heart attack
  • Coronary thrombosis
  • Kawasaki disease
  • Syphilis
  • Hypoparathyroidism

According to Cleveland Clinic dermatologist Christine Poblete-Lopez, horizontal lines on nails can also be a result of chronic stress. Fortunately, these horizontal ridges will often go away after a period of time: You'll have to resolve the health issue causing them, and then allow your nails to grow out past the point of the ridges.

Of course, this also means that people with ongoing chronic illnesses may experience Beau's nails over the long term. If your nails have Beau's lines in them but you haven't had a recent illness, you may want to consult your doctor.

If you have lines in your fingernails that are neither white nor complete horizontal ridges, you may have washboard nails. These are nails with thin, darkened grooves or horizontal ridges on fingernails that tend to occur when your cuticle is frequently picked at or pushed back.

They are unrelated to nutritional deficiencies and other illnesses. These ridges can easily go away as long as your cuticle isn't repeatedly removed or damaged.

Vertical Ridges on Fingernails

Vertical ridges and streaks on your fingernails are caused by different things than horizontal lines on nails. Your nails need blood, just like the rest of your body. Dark brown, black or gray streaks may occur on your fingernails or toenails as vertical, rather than horizontal lines.

If they are particularly dark in color, running from the tip of your nail to your cuticle, they may be because of dilated or burst capillaries. In most cases, lines like these typically occur because of an injury and are usually completely normal.

However, if you haven't recently hurt your finger or toe and have lines like these along your nails, it may be unrelated to blood-flow issues. Some of these dark lines may be a sign of melanoma. Unlike other types of melanoma, this type — known as acral lentiginous melanoma (ALM) — isn't related to sun exposure.

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