What Deficiency Causes Curly Hair? And How Nutrition Shapes Hair Texture

October 12, 2025 •

4 min read

Hair follicles are among the most rapidly dividing cells in the body, which is why nutrient deficiencies can have a profound impact on hair growth and texture. While genetics is the primary determinant of hair type, an interesting medical case has prompted the question: what deficiency causes curly hair?.

Quick Summary

This article explores the relationship between nutrient deficiencies and changes in hair texture. It investigates the specific case linking selenium deficiency to changes in hair and details how common deficiencies, including protein, iron, and zinc, can affect hair health. It emphasizes the importance of a balanced diet for maintaining strong, vibrant hair and discusses how nutritional imbalances disrupt the hair growth cycle, leading to issues like brittleness and shedding.

Key Points

Selenium Deficiency: A documented but rare case reported that severe selenium deficiency caused temporary curly hair in one woman.
Protein's Role: Hair is primarily keratin protein; inadequate intake can cause brittleness, breakage, and thinning.
Iron and Hair Loss: Iron deficiency (anemia) is a major cause of excessive hair shedding (telogen effluvium) and dry, brittle hair.
Zinc and Texture: Zinc is critical for tissue repair and keratin production, and its deficiency can lead to brittle, thinning hair.
Vitamin C and Strength: Vitamin C promotes collagen synthesis, which strengthens hair strands, and its deficiency leads to dryness and breakage.
Balanced Diet is Key: Optimal hair health relies on a varied, nutrient-dense diet, not just one or two specific nutrients.
Deficiency vs. Curl: Most nutritional deficiencies cause damage that can alter hair's perceived texture, rather than fundamentally changing its natural curl pattern.

Unpacking the Link Between Nutrition and Hair Texture

Beyond external factors like styling and products, the food we consume directly influences the health and appearance of our hair. Each hair strand is primarily composed of the protein keratin, and the health of our hair follicles relies on a consistent supply of vitamins, minerals, and proteins. An imbalance in these vital nutrients can lead to a host of hair issues, from thinning and slow growth to noticeable changes in texture. For those who notice unexpected alterations in their hair's curl or texture, looking inward at one's diet can provide valuable clues.

What Deficiency Causes Curly Hair? The Role of Selenium

While genetics and follicle shape dictate natural hair type, a 2022 medical case study reported that a severe deficiency in the trace mineral selenium was the cause of a woman's curly hair. The change was so significant that it led to the specific query: what deficiency causes curly hair? After supplementing with selenium, the woman's hair returned to its original texture. This rare case highlights that while deficiencies typically cause damage rather than a new curl pattern, severe nutritional imbalances can have unexpected and significant effects on hair structure. In most cases, nutrients affect existing hair, causing it to become brittle, dry, or weak, which can alter its appearance and texture.

Key Nutritional Deficiencies Affecting Hair Texture

Several common nutritional deficiencies can lead to changes in hair texture and overall health. Addressing these imbalances is crucial for anyone seeking to improve their hair's vitality.

Protein

As the primary building block of hair, protein is essential for strong, healthy strands. A protein deficiency can lead to hair becoming brittle, dull, and weak. In severe cases, the hair growth cycle can be disrupted, leading to significant shedding, a condition known as telogen effluvium. The lack of protein can cause hair shafts to weaken, leading to breakage that alters the hair's perceived texture and volume. Protein deficiency can result from crash dieting or restrictive eating habits.

Iron

Iron is vital for producing hemoglobin, the protein that carries oxygen to cells, including those in hair follicles. Insufficient iron, or anemia, is a common cause of hair shedding and can make hair feel dry and brittle. For individuals experiencing hair loss, particularly women, low iron stores (ferritin) are frequently observed. Replenishing iron stores can reverse this type of hair loss and restore hair health.

Zinc

This mineral is crucial for hair tissue growth and repair. It plays a role in the function of oil glands around hair follicles, which keep the hair moisturized and shiny. Zinc deficiency has been linked to issues like hair thinning, premature graying, and a dry scalp. The lack of zinc impairs the structural integrity of hair follicles, leading to weaker, more brittle hair.

Vitamin C

Known for its antioxidant properties, Vitamin C is also essential for collagen production, a protein that strengthens hair. A deficiency can lead to dry, splitting, and brittle hair strands. Additionally, Vitamin C aids in the absorption of iron, so a shortage can indirectly exacerbate iron-related hair problems. Incorporating Vitamin C-rich foods is therefore a dual strategy for improving hair health.

Comparison of Key Hair Nutrients


Nutrient	Role in Hair Health	Deficiency Impact	Key Food Sources
Protein	Provides the keratin needed for hair structure.	Brittle, weak, dull hair; excessive shedding.	Eggs, lean meats, fish, lentils, beans.
Iron	Carries oxygen to hair follicles; supports cell growth.	Hair loss (telogen effluvium), thinning, dry hair.	Red meat, spinach, lentils, fortified cereals.
Zinc	Essential for tissue growth, repair, and keratin production.	Thinning, shedding, dry hair, brittle strands.	Oysters, beef, pumpkin seeds, lentils.
Vitamin C	Boosts collagen production; helps iron absorption.	Dry, splitting hair; increased breakage.	Citrus fruits, strawberries, bell peppers, broccoli.
Omega-3s	Nourishes hair follicles and provides moisture.	Dry, brittle hair and a dry, flaky scalp.	Salmon, mackerel, flaxseeds, walnuts.

How to Improve Hair Health Through Diet

Rather than focusing on a single nutrient, the best approach for optimal hair health is a varied, balanced diet. By incorporating a wide range of whole foods, you ensure your body receives the necessary building blocks for strong, vibrant hair. This holistic approach is far more effective than relying on a single supplement.

Prioritize Protein: Include a source of high-quality protein in every meal. Examples include lean meats, fish, eggs, and legumes like chickpeas and lentils.
Load Up on Leafy Greens: Spinach and kale are excellent sources of iron, folate, and vitamins A and C. Pair them with a Vitamin C source like berries for better iron absorption.
Incorporate Healthy Fats: Essential fatty acids found in sources like salmon, avocados, walnuts, and flaxseeds nourish hair follicles and promote shine.
Snack on Nuts and Seeds: Almonds, pumpkin seeds, and sunflower seeds are rich in zinc, vitamin E, and healthy fats, providing essential nutrients on the go.
Stay Hydrated: Water is crucial for transporting nutrients to the hair follicles and keeping the scalp and hair moisturized.
Avoid Crash Diets: Severely restrictive diets can lead to sudden nutrient deficiencies and significant hair shedding.

For more comprehensive nutritional strategies, consulting resources like Harvard's The Nutrition Source can provide excellent guidance on creating a balanced and healthy eating plan.

Conclusion

While genetics primarily determines your hair's natural curl pattern, a person's diet plays a critical role in its overall texture and health. As demonstrated by the rare case linking selenium deficiency to temporary curly hair, severe nutritional imbalances can have unexpected effects. However, for most individuals, common deficiencies in protein, iron, zinc, and Vitamin C are more likely to cause negative changes like thinning, brittleness, and dullness rather than a complete alteration of curl. By focusing on a balanced, nutrient-rich diet and working with a healthcare professional to address any specific deficiencies, you can provide your hair with the optimal environment to thrive, restoring its strength, shine, and natural vitality.

Frequently Asked Questions

While genetics primarily determines your hair's curl, a rare medical case documented a severe selenium deficiency causing hair to become temporarily curly. In most cases, deficiencies cause damage like brittleness or frizz that can alter the hair's appearance and texture.

Iron deficiency, which can lead to anemia, is one of the most common nutrient deficiencies associated with hair loss, particularly excessive shedding known as telogen effluvium.

A lack of zinc can impair hair tissue growth and repair, leading to hair thinning, shedding, and a dry, brittle texture. It also helps regulate the oil glands that moisturize the scalp.

Since hair is made of the protein keratin, a lack of protein can make strands weak, brittle, and dull. It can also disrupt the hair growth cycle, causing increased shedding.

Foods rich in protein, iron, zinc, and vitamins A, C, and E are best. Examples include eggs, leafy greens, berries, nuts, seeds, and fatty fish like salmon.

Yes, in many cases, restoring nutrient levels through a balanced, healthy diet and, if necessary, supplements can reverse hair damage and promote healthy regrowth. However, it requires consistency and time.

Recovery time depends on the severity and duration of the deficiency, but noticeable improvements often begin within a few months of correcting the nutritional imbalance.

While supplements can be helpful for confirmed deficiencies, it is best to consult a healthcare professional. Excess intake of some nutrients can be harmful, so a balanced diet is always the safest and most effective approach.