What am I lacking if my fingernails are brittle?

November 1, 2025 •

4 min read

According to research from Harvard Medical School, nearly 27% of women experience brittle nails. While often dismissed as a cosmetic problem, knowing what am I lacking if my fingernails are brittle can be a vital clue to underlying nutritional deficiencies, external factors, or medical issues. Addressing the root cause is key to restoring strong, healthy nails.

Quick Summary

Brittle fingernails can signal deficiencies in key nutrients like biotin, iron, and zinc, or external factors such as frequent water exposure and harsh chemicals. Underlying health conditions like thyroid problems or anemia can also be responsible. Proper hydration, diet, and careful nail care are essential for improving nail strength.

Key Points

Biotin Deficiency: A lack of vitamin B7 can impair keratin production, leading to brittle nails, but deficiencies are rare.
Iron Deficiency (Anemia): Low iron can cause thin, brittle nails and sometimes lead to a spoon-like shape (koilonychia).
Zinc and Protein: Both are essential for cell growth and nail structure, and low levels can cause brittleness and slow growth.
Frequent Wetting/Drying: Overexposure to water can strip nails of natural oils, making them dry and prone to breaking.
Harsh Chemicals: Exposure to strong cleaning products and acetone-based removers can weaken the nail plate.
Underlying Medical Conditions: Thyroid disorders, anemia, and Raynaud's syndrome are systemic issues that can cause brittle nails.
Age and Hydration: Nails naturally become more brittle with age, and general dehydration can also play a significant role.
Proper Nail Care: Using a good moisturizer, wearing gloves for housework, and avoiding aggressive manicures can help prevent brittleness.

Common Nutritional Deficiencies Associated with Brittle Nails

Your fingernails are a window into your overall health, and their condition is often a reflection of your body's internal state. The nails are made primarily of keratin, a fibrous structural protein, and the body requires a steady supply of essential vitamins and minerals to produce strong, healthy nails. A deficiency in any of these key nutrients can compromise this process, leading to brittle, splitting, or weak nails.

Biotin (Vitamin B7)

Perhaps the most well-known nutrient for nail health, biotin plays a crucial role in the production of keratin. A deficiency, though rare, can lead to brittle and splitting nails. Studies have shown that supplementing with biotin can significantly improve nail thickness and reduce breakage in individuals with brittle nail syndrome.

Biotin-Rich Foods: Eggs, almonds, sweet potatoes, and salmon.

Iron

Iron is vital for the transport of oxygen to all cells in the body, including the nail bed. A deficiency, or anemia, can hinder nail growth and lead to brittle, thin nails that may develop a characteristic spoon-like shape (koilonychia).

Iron-Rich Foods: Red meat, lentils, spinach, and fortified cereals.

Zinc

This mineral is essential for cell growth and division, both of which are critical for forming new nail cells. Inadequate zinc intake can cause white spots on the nails (leukonychia), slow growth, and increase brittleness.

Zinc-Rich Foods: Oysters, beef, pumpkin seeds, and chickpeas.

Protein

Since nails are primarily made of keratin protein, insufficient dietary protein can directly impact their strength. A lack of adequate protein intake can result in weak and peeling nails.

Protein-Rich Foods: Lean meats, fish, eggs, dairy, and legumes.

Other Important Nutrients

Other nutrients that support nail health include:

Calcium and Vitamin D: Work together for strong nail structure.
Omega-3 Fatty Acids: Help to keep nails hydrated and prevent dryness.
Vitamin C: Essential for collagen production, providing strength and elasticity to the nail.

External Factors and Medical Conditions

Beyond nutritional deficits, several other factors can cause brittle fingernails. These can range from simple environmental issues to more complex medical conditions.

Environmental Causes

Frequent exposure to water is a leading external cause of brittle nails, as repeated wetting and drying strips the nails of their natural oils. Harsh chemicals in cleaning products, nail polish removers containing acetone, and even excessive use of alcohol-based hand sanitizers can also damage the nail plate.

Medical Conditions

Sometimes, brittle nails can be a symptom of a deeper health issue. It is important to consult a doctor if you notice persistent changes in your nails or experience other accompanying symptoms.

Hypothyroidism: An underactive thyroid can slow down the body's metabolism and affect nail growth, leading to thick, brittle nails.
Raynaud's Syndrome: This condition affects blood circulation in the extremities, reducing the oxygen and nutrient supply to the nails, which can make them brittle.
Fungal Infections: Infections can cause nails to thicken, change color, and become brittle.

Comparing Causes of Brittle Fingernails


Cause	Mechanism	Key Indicators	Recommended Action
Nutritional Deficiency	Lack of essential vitamins and minerals (e.g., biotin, iron, zinc) impacts keratin production and cell health.	Brittle nails, vertical ridges, spoon shape, or white spots, possibly with other deficiency symptoms like fatigue.	Improve diet with nutrient-rich foods, consider supplementation after consulting a doctor.
Dehydration	Inadequate water intake or excessive wetting/drying cycles deplete the nail plate of moisture.	Dry, dull nails that peel easily.	Stay hydrated by drinking plenty of water and use a hand moisturizer frequently.
Harsh Chemicals	Ingredients in cleaning supplies and acetone-based removers strip the nails of natural oils.	Weakened, peeling nails, often with peeling around the cuticle area.	Wear protective gloves for wet work and use acetone-free nail polish removers.
Underlying Medical Condition	Systemic disorders (thyroid issues, anemia, Raynaud's) disrupt overall bodily functions, including nail growth.	Brittle nails accompanied by other symptoms like fatigue, weight changes, or circulation problems.	Consult a healthcare professional for diagnosis and treatment of the root cause.

How to Strengthen Your Nails

Moisturize Regularly: Apply hand cream or cuticle oil after washing your hands to keep your nails and cuticles hydrated.
Wear Gloves: Use rubber gloves when doing household chores involving water or chemicals.
Adopt a Nail-Strengthening Diet: Ensure your diet is rich in protein, biotin, iron, and zinc.
Avoid Harsh Products: Opt for acetone-free polish removers and minimize the use of gel or acrylic manicures.
Consider Supplements: For specific deficiencies, a doctor-recommended supplement can help. However, patience is key, as significant improvement can take several months.

Conclusion

If you find yourself asking, 'what am I lacking if my fingernails are brittle?', the answer can range from simple dehydration to a more significant nutritional or medical issue. While external factors like harsh chemicals and frequent water exposure are common culprits, underlying deficiencies in biotin, iron, and zinc are often the root of the problem. By adopting a nutrient-rich diet, practicing good nail care, and addressing any underlying medical conditions, you can effectively restore your nails' strength and resilience. For persistent concerns, a visit to a healthcare provider is the best course of action to ensure proper diagnosis and treatment.

For more detailed information on nail health, you can visit the NHS page on nail problems.

Frequently Asked Questions

Biotin (vitamin B7) deficiency is often cited as a cause of brittle nails, as it is crucial for keratin production. Iron deficiency and anemia are also very common culprits, especially in women.

Yes, dehydration can be a significant cause. When the body lacks sufficient water, it can lead to dryness in the hair, skin, and nails, making them brittle and more prone to breakage.

Yes, both an underactive (hypothyroidism) and overactive (hyperthyroidism) thyroid can affect nail health. Hypothyroidism, in particular, can lead to brittle and ridged nails due to a slowed metabolism.

Brittle nails can be a sign of iron deficiency anemia. Low iron levels can cause nails to become thin and brittle, sometimes leading to a characteristic spoon shape called koilonychia.

If only your fingernails are affected and you frequently engage in wet work (e.g., washing dishes) or use harsh chemicals, the cause is likely external. If both your fingernails and toenails are brittle, an internal issue like a nutritional deficiency or medical condition is more likely.

Studies have shown that biotin supplementation can improve nail thickness and reduce splitting in people with brittle nails. However, this is primarily effective if you have an underlying biotin deficiency.

To strengthen brittle nails at home, moisturize regularly with a hand cream or cuticle oil, wear gloves for housework, and ensure your diet is rich in protein, iron, and zinc. Avoiding acetone-based polish removers is also beneficial.