What vitamin deficiency causes rough fingernails and other nail abnormalities?

October 30, 2025 •

2 min read

According to dermatological experts, fingernails and toenails can provide valuable insights into our overall health, acting as a visual report on our nutritional status. Numerous factors can influence nail health, but the question of what vitamin deficiency causes rough fingernails is a common concern that can often be addressed with dietary changes.

Quick Summary

Several nutritional deficiencies are linked to rough and brittle nails. Identifying the specific deficiency requires a medical evaluation, as treatment involves targeted dietary changes or supplements.

Key Points

Biotin (Vitamin B7): Deficiency can cause brittle, splitting, and ridged nails due to its role in keratin production.
Iron Deficiency: Low iron levels can lead to rough, brittle, and even spoon-shaped nails (koilonychia) by impacting oxygen transport.
Zinc Deficiency: An inadequate intake of zinc can cause brittle nails, white spots, and horizontal grooves (Beau's lines).
Vitamin C and Protein: Both are vital for collagen and keratin synthesis, respectively, and low levels can lead to brittle nails and slow growth.
Dietary Correction is Key: Addressing the nutritional root cause through a balanced diet rich in essential vitamins and minerals is the most effective approach.

The Connection Between Nutrition and Nail Health

Your nails are primarily made of keratin, a fibrous protein. Healthy nail growth relies on essential vitamins and minerals for proper keratin synthesis. A deficiency can disrupt this process, potentially causing abnormalities.

Vitamin Deficiencies and Nail Symptoms

Several specific deficiencies are commonly linked to rough or brittle fingernails:

Biotin (Vitamin B7): Crucial for keratin production, deficiency can lead to brittle, splitting, and ridged nails. While rare, supplements may help those with a confirmed deficiency. Good sources include eggs and nuts.
Iron: Essential for oxygen transport to the nail matrix. Deficiency can cause brittle, rough nails, and in severe cases, spoon-shaped nails (koilonychia) and pronounced vertical ridges. Increasing iron intake through foods like red meat and spinach can help.
Zinc: Important for cell growth and repair needed for nail growth. Low levels can result in brittle nails, white spots (leukonychia), and horizontal grooves (Beau's lines). Oysters and nuts are good sources.
Vitamin C: Necessary for collagen production, which supports nail structure. Severe deficiency can cause brittle nails, splinter hemorrhages, and slow growth. Citrus fruits are rich in Vitamin C.

Comparison Table of Deficiencies and Nail Symptoms


Nutrient	Associated Nail Symptoms	Other Signs of Deficiency
Biotin (B7)	Brittle, splitting, or ridged nails	Hair loss, dry skin, fatigue
Iron	Brittle nails, vertical ridges, koilonychia (spoon nails), paleness	Fatigue, headaches, pale skin
Zinc	Brittle nails, white spots, Beau's lines	Hair loss, diarrhea, poor wound healing
Vitamin C	Brittle nails, slow growth, splinter hemorrhages	Easy bruising, bleeding gums, fatigue
Vitamin B12	Blueish or brown-gray nail discoloration, possibly ridges	Fatigue, nerve problems, mood changes

Beyond Nutritional Deficiencies

Rough fingernails aren't solely caused by vitamin deficiencies. Other factors include:

Aging: Nails can become naturally more brittle.
Moisture Exposure: Frequent wetting and drying can cause brittleness.
Chemicals: Exposure to harsh cleaning products or nail treatments can damage nails.
Health Conditions: Thyroid issues, psoriasis, or fungal infections can impact nail texture.

Promoting Healthier Nails

If you have concerns about your nail texture, consult a healthcare provider to identify the cause. Dietary changes and proper nail care can improve nail health. Focusing on foods rich in biotin, iron, zinc, and Vitamin C is beneficial. Including lean proteins and sources of omega-3 fatty acids also supports nail health.

Conclusion

Rough fingernails can stem from various causes, but addressing potential vitamin deficiencies is crucial for improving nail health. A balanced diet rich in essential nutrients, alongside protecting your nails from damage, is key to promoting strength and smooth texture. For persistent issues, professional medical advice can help determine the exact cause and treatment. For further information on nutrient deficiencies, resources like the National Institutes of Health are valuable.

Frequently Asked Questions

While multiple deficiencies can contribute, biotin (Vitamin B7) deficiency is one of the most commonly cited vitamin-related causes for rough and brittle nails.

Yes, a lack of iron, which can lead to anemia, often causes nails to become thin, brittle, and rough. In severe cases, it can also lead to spoon-shaped nails, a condition called koilonychia.

Zinc deficiency can cause nail dystrophy, which includes signs like brittle and rough nails, as well as the appearance of white spots or horizontal grooves called Beau's lines.

Yes, since nails are made of keratin, a type of protein, insufficient protein intake can lead to weak and brittle nails. Ensuring adequate protein is crucial for strong nail growth.

Apart from nutritional issues, common factors include the natural aging process, frequent exposure to water and harsh chemicals, and certain underlying health conditions like thyroid disorders.

Biotin supplements can be beneficial, especially for those with a confirmed deficiency. However, it's best to consult a healthcare provider first, as a supplement may only work if a deficiency is the underlying cause.

Because nails grow slowly (around 3mm per month), it takes several months for healthy nail growth to replace the damaged nail. Consistency in dietary changes and proper care is key to seeing improvement.