Your Hair Is Telling You Something: What Thinning, Dullness, and Slow Growth Really Mean

2 May 2026

Your hair is like a mirror to your overall health. Common hair issues, such as thinning, dullness, and slowed growth, could indicate anything from nutritional deficiencies to underlying health conditions.

In this article, we focus on the nutritional gaps that might be causing your hair problems.

What Is Your Hair Made of?

Human hair has two distinct structures.

  • The hair shaft: The visible part lying outside the skin. It has three layers: the outermost protective cuticle, the middle cortex thatkeeps hair strong, elastic, and moist, and the innermost medulla (provides thickness to the hair, may be absent in fine hair).
  • The hair follicle: It lies underneath the scalp’s surface and is responsible for generating hair shafts.

Proteins make up 65% to 95% of the total hair weight. The primary protein is keratin, which is mainly made of three amino acids: tyrosine, glycine, and cysteine.

Further Reading: Healthy hair starts from the inside: What is keratin and what role does it play in maintaining healthy hair?

How Does Your Hair Grow?

Hair grows in a cyclical process, which comprises four separate stages:

  1. Anagen: Growing phase during which hair follicles keep pushing out hairs
  2. Catagen: Transition phase where the follicles shrink, leading to slowed growth
  3. Telogen: Resting phase during which your hair neither grows nor falls out
  4. Exogen: Shedding phase, lasting for several months. It’s normal to lose 50 to 100 hairs daily during this phase.

Age, nutritional status, and overall health can affect each phase.

Hair Thinning Could be a Sign of Nutritional Deficiencies

Not all types, but some, including diffuse hair, could signal nutritional deficiencies.

Diffuse hair loss is when you start shedding hair evenly from all areas of the scalp. It usually does not involve scarring or inflammation.

Studies have found a link between diffuse thinning and deficiencies of vitamin D, zinc, and iron. (1) Your odds of getting diffuse hair loss may be higher if you consume too little daily calories or protein, or if you have been crash dieting for an extended period.

Vitamin D for hair thinning

Vitamin D is a fat-soluble nutrient. It is essential for healthy bones, muscles, and immune regulation. While the exact mechanism is unclear, vitamin D is thought to help your body make  cells that will eventually grow into hair follicles. (2)

Also Read: How Low Vitamin D Levels Impair Your Immune Health

In a 2024 study involving 120 participants with diffuse hair loss, researchers found that almost 80% had low vitamin D levels. (3) The finding is similar to that of a 2016 study, which found vitamin D deficiency in over 80% of all participants with diffuse hair loss. (4)

While the benefits of vitamin D seem promising for hair loss, more studies are needed to confirm the potential benefits. However, it is safe to say that getting your daily recommended dose is essential regardless of whether you have hair loss or not.

How much vitamin D you need daily

Adults and children older than one year should get 10 micrograms (mcg) of vitamin D daily. The government also recommends a daily vitamin D (10 micrograms) supplement during the autumn and winter. (5)

Food sources of vitamin D are oily fish, red meat, egg yolks, fortified foods, and liver.

Zinc for hair thinning

Zinc is an essential micronutrient. Your body needs zinc to make new cells and enzymes, process dietary carbohydrates, fat and protein, and aid wound healing.

In many people with a type of hair loss called alopecia areata, zinc levels are significantly lower. Likewise, lower zinc levels are associated with more severe hair loss among these people.

Interestingly, a three-decade-old study found that daily zinc supplementation reversed hair loss in obese people who underwent surgery to limit the amount of food intake. The dosage used in this study was 200 mg of zinc sulphate three times a day. (6)

However, this finding should be taken with a pinch of salt because it has not been replicated in newer, larger studies and the surgical procedure is rarely used today.

How zinc affects hair loss is largely unknown. However, researchers think zinc, as an essential component of enzymes involved in hair growth regulation, may help reduce hair loss.

Moreover, studies show zinc blocks the catagen phase of the hair cycle. (7) Hair growth is slowed during the catagen phase. By blocking catagen, zinc may help hair stay in the growth phase (anagen) for longer.

How much zinc you need daily

The NHS recommends a daily intake of 9.5 mg for men and 7 mg for women. Good dietary sources of zinc are meat, shellfish, dairy foods, bread, and cereal products. (8)

Note: While investigating the causes of hair loss, routine zinc testing is not recommended.

Iron for hair thinning

Iron is an essential element. Your body uses iron to make haemoglobin, a protein that carries oxygen throughout the body.

When you have low iron levels in the body, it cannot make enough haemoglobin. Consequently, oxygen delivery to the cells that stimulate hair growth is impaired.

While debatable, iron deficiency is considered a significant contributor to hair loss, particularly in women. However, the level of deficiency that contributes to hair loss is still unclear.

How much iron you need daily

The recommended daily intake is: (9)

  • 8.7mg daily men (19 years and older)
  • 14.8mg daily for women (19 to 49 years)
  • 8.7mg daily for women (50 years and older)

Foods rich in iron include liver, red meat, beans, nuts, and soy bean flour.

Premature Grey Hair Could be a Sign of Copper Deficiency

Your body needs copper to produce melanin, a pigment that determines your hair colour. So, copper deficiency may contribute to premature grey hair.

How much copper you need daily

The NHS recommends 1.2 mg of copper daily for adults between 19 and 64 years. Rich sources of copper are nuts, shellfish, and offal. (10)

Rapid Hair Loss Could be a Sign of Low Protein Intake

Low protein intake, which is rare in the UK, could be causing your hair to shed rapidly or break easily.

Before we learn more, let’s get to the biology of our body and hair.

Our body does not consider hair essential for survival. As such, it directs available proteins for other bodily functions/organs required for survival. As a result, our hair is rarely prioritised when the body starts distributing protein.

So, even when you take enough protein, your hair might not get the amount it needs. Not to forget, only half of the UK adults between 65 and 89 years meet the current government recommendation of 0.75 g/kg/day. (11)

Coupled with age-related changes, protein deficiency is a double whammy for older UK adults.

Do collagen supplements help?

When we talk about protein, collagen is likely the first thing to come to our mind. Yes, collagen supplements can help.

When you take an oral collagen, it breaks down into amino acids, mainly glycine, hydroxyproline, and proline. Once absorbed from the gut into the bloodstream, these amino acids reach the skin, where they stimulate new collagen formation.

Studies show that dietary collagen may increase hair thickness and help control stress-related hair loss. (12)

Which Collagen Supplement to Choose

When looking for a collagen supplement, opt for the one that contains adequate doses of high-quality collagen, vitamin C, B vitamins, and copper. This combo is the best for your hair, skin, and nails.

Lastly, go for a liquid supplement. Find out why liquid supplements beat tablets

Cannot find one that best meets your needs? That’s why we made CUTIZANA. Each daily serving of CUTIZANA is packed with 10,000mg of premium marine collagen (types I & III), plus hyaluronic acid, biotin, amino acids, and more.

Find out more about CUTIZANA here.

References:

  1. Harrison, S., & Bergfeld, W. (2009). Diffuse hair loss: Its triggers and management. Cleveland Clinic Journal of Medicine, 76(6), 361–367. https://doi.org/10.3949/ccjm.76a.08080
  2. Pa-C, J. F. M. (2024, April 22). Vitamins, minerals, and hair loss: Is there a connection? Harvard Health. https://www.health.harvard.edu/diseases-and-conditions/vitamins-minerals-and-hair-loss-is-there-a-connection
  3. Jalil, Palwasha et al. “Filling the Gaps: Vitamin D Status in Diffuse Hair Fall Among Pakistanis.” Dermatology practical & conceptual vol. 14,4 e2024232. 30 Oct. 2024, doi:10.5826/dpc.1404a232
  4. Nayak, Kashinath et al. “Serum Vitamin D3 Levels and Diffuse Hair Fall among the Student Population in South India: A Case-Control Study.” International journal of trichology vol. 8,4 (2016): 160-164. doi:10.4103/ijt.ijt_57_16
  5. Website, N. (2025, May 23). Vitamin D. nhs.uk. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/
  6. Neve, HJ et al. “Reversal of Hair Loss following Vertical Gastroplasty when Treated with Zinc Sulphate.” Obesity surgery vol. 6,1 (1996): 63-65. doi:10.1381/096089296765557295
  7. Lalosevic, Jovan et al. “Serum Zinc Concentration in Patients with Alopecia Areata.” Acta dermato-venereologica vol. 103 adv13358. 3 Oct. 2023, doi:10.2340/actadv.v103.13358
  8. Website, N. (2025b, June 5). Others. nhs.uk. https://www.nhs.uk/conditions/vitamins-and-minerals/others/
  9. Website, N. (2023, August 3). Iron. nhs.uk. https://www.nhs.uk/conditions/vitamins-and-minerals/iron/
  10. Website, N. (2025c, June 5). Others. nhs.uk. https://www.nhs.uk/conditions/vitamins-and-minerals/others/
  11. Morris, Susan et al. “Inadequacy of Protein Intake in Older UK Adults.” Geriatrics (Basel, Switzerland) vol. 5,1 6. 12 Feb. 2020, doi:10.3390/geriatrics5010006
  12. Vargas-Mendoza, Nandiani, et al. “Effectiveness of a Food Supplement Based on Hydrolyzed Collagen and Vitamins in Hair Loss and Hair Quality: A Randomized, Placebo-Controlled, Double-Blind Clinical Trial.” Journal of Functional Foods, vol. 115, Apr. 2024, art. 106126, https://doi.org/10.1016/j.jff.2024.106126.