By Meagan Purdy, ND
When your hair feels thin, brittle, or just not like it used to, your body may be sending you an important signal. Hair is metabolically expensive to grow and maintain, but it’s not essential for survival. That means when nutrients are limited, your body will always prioritize your heart, brain, and other vital organs over your hair. The result? Deficiencies show up quickly in hair, skin, and nails.1
In this post, we look at why nutrition is so central to hair health, which nutrients matter most, and how supplementation can help restore strong, resilient strands.
Why Hair Reflects Nutrient Deficiency
Hair grows in cycles, spending most of its time in the growth (anagen) phase. To stay there, follicles rely on a steady supply of fuel: oxygen, amino acids, vitamins, and minerals. If even one key nutrient is missing, follicles can exit growth prematurely, leading to more shedding, or produce weaker shafts that break easily.1
Think of your hair like a garden. If the soil is missing minerals, the plants grow smaller and weaker—even if the seeds are healthy. Follicles behave the same way: They need a nourished environment to thrive.
The Key Nutrients for Hair
Iron
Iron delivers oxygen to the rapidly dividing cells in the hair matrix. Without enough iron, follicles leave the growth phase early, triggering increased shedding and thinner strands.1
Zinc
Zinc is essential for DNA synthesis and keratin assembly. Low zinc levels mean keratin is poorly made, resulting in brittle hair and disrupted cycling.1
Vitamin D
Hair follicles contain vitamin D receptors. Deficiency can impair stem cell activation, making it harder for follicles to reenter the growth phase.1
B Vitamins
Vitamin B6, B12, and folate help form red blood cells and support methylation, which keeps nutrients flowing to follicles. Without them, hair can thin, and regrowth slows.2,3
Protein, Collagen, and Keratin: The Building Blocks
While vitamins and minerals create the conditions for growth, protein provides the raw materials. Hair is over 90% protein, and without an adequate supply, keratin production stalls. That’s why diets too low in protein often cause hair shedding.
Two nutrients stand out when it comes to rebuilding strong, resilient strands: collagen peptides and keratin.
- Collagen peptides supply amino acids like glycine, proline, and hydroxyproline that directly fuel follicle metabolism. In a clinical study, women taking collagen peptides saw a measurable increase in hair thickness within just 16 weeks.4,5
- Keratin is the protein that makes up the hair shaft itself. Supplementing with keratin has been shown to improve hair strength, shine, and resistance to breakage.6
Together, collagen peptides and keratin reinforce both the follicle’s metabolic machinery and the structural integrity of the hair fiber.
How to Support Hair Through Nutrition
If you’re experiencing shedding, brittle strands, or slow regrowth, it may be time to look at nutrition. Correcting deficiencies in iron, zinc, B vitamins, and vitamin D can help reset the hair cycle, while adding protein, collagen, and keratin provides the building blocks for new, stronger growth.
The bottom line: when your body is well-nourished, your hair is, too. By feeding your follicles what they need, you’re not just improving hair appearance—you’re restoring the foundation for long-term hair wellness.
Learn more about hair growth support:
- Why Hormones Affect Women’s Hair
- The Science of Antioxidants for Hair Growth
- Hair Growth Products: A Complete Guide to Stronger, Thicker Hair
References
1. Guo EL et al. Dermatol Pract Concept. 2017;7(1):1-10.
2. Almohanna H et al. Dermatol Ther (Heidelb). 2019;9:51-70.
3. Labrozzi A. Hair Ther Transplant. 2020;10(1):150.
4. Oesser S et al. J Nutr. 2004;134(11): 3124–3129.
5. Oesser S. Nutrafoods. 2020;1:134-138.
6. Martin-Biggers J et al. J Clin Aesthet Dermatol. 2024;17(11):34-38.
