Your fingernails can say a lot about you, including whether or not you're consuming enough vitamins and minerals. Getting insufficient amounts of certain B-complex vitamins can cause ridges in your fingernails. However, lack of certain minerals and protein, as well as various health conditions, can cause these lines in fingernails too.
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."
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A variety of different nutrients play a role in good nail health. A November 2015 study in the Tropical Doctor Journal discussed how minerals like calcium, copper, iron, magnesium, sodium and zinc are particularly important for your nails. However, it's not just these minerals that make a difference — other nutrients like biotin, folic acid and protein are just as important to nail health.
If you're deficient in certain nutrients or have ongoing health issues, you may see changes in your nails that include discoloration, ridges or lines in fingernails. Some lines in fingernails can signal serious health problems, while others are simply due to impact or injury. However, with the exception of zinc, folic acid, iron or protein deficiencies, nutrient deficiencies are unlikely to be the cause of your fingernail ridges.
Nutritional Deficiencies and Your Nails
While your health can certainly affect your nails, horizontal or vertical ridges on nails and vitamin deficiencies are rarely correlated with one another. However, according to an April 2015 study in the Indian Dermatology Online Journal, folic acid, iron and protein deficiencies can all cause central ridges.
Zinc deficiencies can result in Beau's lines, which are horizontal ridges on fingernails. However, Beau's lines are also caused by many other health issues. Deficiencies in zinc, calcium or B-complex vitamins may also cause transverse leukonychia — white streaks or horizontal lines on nails, rather than ridges or indentations.
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.
The majority occur because of injuries or even light impact, like tapping your nails against hard surfaces or repeated manicures, rather than nutrient deficiencies. The exception to this is Muehrcke's lines, parallel white lines that extend across your nails. These white, horizontal lines on nails are a sign of low protein levels in your blood. They can occur due to health problems like malnutrition or liver disease.
In most cases, ridges on your nails are a sign of more severe issues. Horizontal and vertical lines running the full length of your nails can often be tied to 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:
- Peripheral vascular disease
- Scarlet fever
- Exposure to extreme cold
- Heart attack
- Coronary thrombosis
- Kawasaki disease
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.
Vertical lines in fingernails are most likely to be of concern when you haven't had any injuries or impacts but the area surrounding the streak has damaged your nail. If you see any vertical brown lines that run into your cuticle, contact your dermatologist as soon as possible to have them assessed.
- Cleveland Clinic: "6 Things Your Nails Say About Your Health"
- HuffingtonPost Life: "15 Things You Never Knew About Your Nails"
- Tropical Doctor: "Diffuse Melanonychia as a Clue to Vitamin B12 Deficiency"
- NIH: "Biotin Fact Sheet for Health Professionals"
- Indian Dermatology Online Journal: "Nail as a Window of Systemic Diseases"
- Mayo Clinic: "Healthy Lifestyle Fingernails: Possible Problems"
- Indian Journal of Dermatology Venereology and Leprology: "Nails in Nutritional Deficiencies"
- Beacon Medical Group NHS: "Muehrcke's Lines"
- American Academy of Dermatology: "12 Nail Changes a Dermatologist Should Examine"
- Aim at Melanoma Foundation: "Acral Lentiginous Melanoma (ALM)"