You look at them every day, but you probably take your fingernails for granted. In fact, they can tell you a lot about your health. Brittle nails that split easily or nails flattening out can be a sign of several health conditions. Although rare, deficiencies in certain nutrients, including vitamin A, may also be to blame.
Causes of Fingernail Changes
Your fingernails are a lot like your skin and can be affected by myriad dermatologic and systemic conditions. Common causes of alterations in fingernail size, shape and color include:
- Alopecia (hair loss)
- Nutrient deficiencies
Fingernail abnormalities typically manifest in one of several ways:
- Beau's lines, which are depressions across the fingernail.
- Brittle nails.
- Koilonychia, or spoon nails, in which the fingernail is abnormally shaped. The nails may be thin, have raised ridges and curve inward.
- Leukonychia, characterized by white streaks or spots on the nails.
- Pitting, or small depressions, on the nail surface. The nails may also crumble, become loose or fall off.
- Ridges, which are small raised lines that can appear vertically or horizontally on the nail surface.
According to MedlinePlus, the most likely fingernail changes associated with nutrient deficiencies are beau's lines and koilonychia. Dry, brittle nails and discoloration are other potential manifestations.
Potential Vitamin Deficiencies
Deficiencies in most vitamins are rare in developed countries, but several factors can increase the risk. These include low income, restrictive diets, medications, alcoholism and inadequate dietary intake in people who are sick and the elderly, according to Kristine Hoffman, DPM. However, with the rise in popularity of restrictive weight loss diets, as well as vegan and vegetarian diets, nutrient deficiencies that affect the fingernails are an increasing risk. This is especially true if the diets are not well-planned.
Low amounts of any of the vitamins involved in nail health could cause fingernail abnormalities — for example, the B vitamin biotin is a water-soluble nutrient that aids macronutrient metabolism. Biotin deficiency is very rare, according to a June 2018 article in the Journal of the American Academy of Dermatology; however, intravenous feeding that lacks biotin, long-term consumption of raw eggs and a hereditary condition that impairs biotin absorption could cause low levels of the nutrient.
In addition to brittle nails, biotin deficiency may also cause:
- Thinning hair
- Body hair loss; rash around the nose, mouth, eyes and anal area
- Acidic blood and urine
- Skin infection
- Seizures and nervous system disorders
Only your doctor can tell you if you are deficient in biotin. If a blood test comes back positive, taking a biotin supplement will help repair the deficiency, as will eating a diet abundant in biotin-rich foods such as meat, fish, cooked eggs, seeds and nuts.
Deficiency in another B vitamin, B12, can cause hyperpigmentation of the nails, according to an article in BMJ Case Reports in March 2018. These changes may appear as a bluish discoloration or dark, longitudinal streaks that may be reticulated, or spread out like a lacey network.
B12 deficiency is common among vegans and vegetarians who eat little or no animal products, which are the main dietary sources of the nutrient. The authors report that nail changes associated with B12 deficiency are more common in people with dark skin, so vegans with deeper skin tones may be especially at risk.
Other causes of B12 deficiency may include weight loss surgery, conditions such as celiac and Crohn's disease, which interfere with nutrient absorption, and heartburn medications that can also reduce absorption. Symptoms of B12 deficiency include:
- Numbness and tingling in the extremities
- Difficulty walking, including staggering and balance problems
- Swollen, inflamed tongue
- Cognitive difficulties
- Memory loss
- Anemia, a condition characterized by low red blood cell levels
If your doctor finds that you are low in the nutrient, B12 therapy can reverse the nail symptoms, according to the authors of the BMJ Case Reports article. You can also increase your dietary intake of foods such as seafood, milk, cheese, and fortified milks and cereals.
Vitamin D Deficiency
Deficiencies in the "sunshine vitamin," vitamin D, can also cause nail changes, reports an article published in April 2012 in the Indian Journal of Dermatology, Venereology and Leprology. Most likely, this is due to the interdependent relationship between vitamin D and the mineral calcium, which plays a role in nail health. Vitamin D helps the body absorb calcium, and a deficiency in the vitamin can cause low levels of the mineral. When this happens, the body leaches calcium from other stores in the body — primarily the bones.
Over 40 percent of Americans are deficient in vitamin D, according to Stephanie Wheeler, Director of Wellness at Mercy Medical Center. Vitamin D primarily comes from the sun; when exposed to sunlight, the skin synthesizes the nutrient. However, most people don't get enough direct sunlight exposure to make everything the body needs. According to the National Institutes of Health, vitamin D is present in very few foods, which compounds the problem.
Other factors and conditions can cause vitamin D deficiency, including:
- Celiac disease
- Bariatric surgery
- Chronic kidney or liver disease
- Long-term medication use for heartburn, acid reflux and constipation
In addition to nail changes, Wheeler reports that vitamin D deficiency is associated with mood swings, depression, low energy, chronic skin conditions and other chronic diseases. Doctors typically recommend supplementation to repair a deficiency. In addition, exposing your skin without sunscreen to sunlight for short periods of time between 10 a.m. and 3 p.m. can also help. You can also eat more vitamin D-rich foods such as swordfish, tuna, salmon and fortified dairy and cereal.
Mineral Deficiencies to Blame
Minerals are micronutrients you need in much smaller amounts than vitamins, but they can still cause big problems when blood levels are too low. Iron deficiency is the most prevalent mineral deficiency in the world, according to an article published in Dermatology Practical & Conceptual in January 2017.
Malabsorption issues and excessive iron losses — for example, in women with heavy periods — are common causes of iron deficiency. In addition, vegans and vegetarians are at a higher risk because the type of iron found in plants is not as easily absorbed as the type found in meat. According to the authors of the Dermatology Practical & Conceptual article, non-meat eaters need 1.8 times the amount of iron that meat eaters require.
Iron deficiency anemia may cause the nails to become brittle and split easily. It can also cause the nail beds to appear pale, and the nails themselves may exhibit koilonychia, or nails flattening out or becoming concave. Other symptoms of iron deficiency anemia include:
- Extreme fatigue
- Pale skin
- Chest pain, fast heartbeat, shortness of breath
- Headaches and dizziness
- Inflamed, sore tongue
- Cold hands and feet
- Odd cravings for non-nutritive substances such as ice or dirt
- Poor appetite
Other mineral deficiencies that may affect the nails include zinc, which may cause transverse leukonychia, Beau's lines and brittle nails, and selenium, which can lead to soft, flaky nails that tend to split and break easily.
There are many other explanations for changes in your nails. The reason may be as benign as repeated wetting and drying of the nails that may occur in certain occupational situations, or it may be a sign of a more serious, underlying condition. The best way to determine the reasons for changes in your nails is to visit your doctor.
- MedlinePlus: "Nail Abnormalities"
- Podiatry Today: "When Vitamin and Nutritional Deficiencies Cause Skin and Nail Changes"
- Journal of the American Academy of Dermatology: "Rethinking Biotin Therapy for Hair, Nail, and Skin Disorders"
- NIH: "Biotin"
- BMJ Case Reports: "Blue Nails: Window to Micronutrient Deficiency"
- Harvard Health Publishing: "Vitamin B12 Deficiency Can Be Sneaky, Harmful"
- NIH: "Vitamin B12"
- Indian Journal of Dermatology, Venereology and Leprology: "Nails in Nutritional Deficiencies"
- NIH: "Calcium and Vitamin D: Important at Every Age"
- Mercy Medical Center: "42% Percent of Americans Are Vitamin D Deficient. Are You Among Them?"
- NIH: "Vitamin D"
- Dermatology Practical & Conceptual: "Diet and Hair Loss: Effects of Nutrient Deficiency and Supplement Use"
- Mayo Clinic: "Iron Deficiency Anemia"