Our general health is often reflected in the condition of our hair and nails: as we grow older, they become thinner and more brittle and the rate of hair growth and renewal slows down. Age weakens the hair and makes the hair shaft more vulnerable to over-handling. Disease, fatigue and stress can also affect the hair’s appearance.
Nutrients such as the B group vitamins, sulphur-containing amino acids, and essential minerals like zinc or silicon, can - by incorporating themselves into the keratin in hair and nails - promote growth and improve the appearance of the hair and nails.
Keratin makes up 95% of hair
The hair is composed of a bulb and a hair shaft. It develops in concentric layers from the hair follicle. Cells multiply in the bulb at the hair root, nourished by oxygen and nutrients transported there by blood capillaries. As they get gradually pushed upwards, these cells become loaded with keratin – a protein rich in sulphur-containing amino acids (cystine and methionine) – to form the hair shaft, which is made up of three concentric layers:
- the innermost layer is the medulla, the exact function of which is unknown. It is formed of lightly pigmented, nuclei-free cells;
- the next layer is the cortex which gives the hair its strength. It is composed of cells rich in keratin and melanin, the pigment that determines hair colour;
- the outer layer is the external root sheath or cuticle, which is similar in composition to the epidermis. The internal root sheath is rich in glycoproteins and contains essential nourishment for the development of the hair. It protects its internal structure.
The hair growth cycle has three successive phases: growth (anagen phase), transitional (catagen phase) and resting (telogen phase) which culminates in the hair falling out, followed by new growth. This cycle begins in the womb from around the fifth month of pregnancy, and continues throughout life.
The nails, a horny layer made of keratin
The nail is a horny layer which is flexible, smooth and translucent, a superficial overgrowth of the skin consisting of very thick, homogenous, keratinized cells. This forms a matrix which keeps the cells welded together and gives the nail its strength, toughness, solidity and flexibility. The nail also contains water, lipids and minerals such as calcium, zinc or silicon.
The nail is enveloped by an epidermal matrix which is where the cells are formed that create the nail. A healthy nail grows an average of 0.10mm a day.
Keratin, a protein rich in sulphur-containing amino acids
Keratin is a scleroprotein – and a protein that is actually made up of a combination of 18 amino acids, most of which are sulphur-containing, such as cysteine or methionine. Thus the hair is also made up of 14% cysteine, and the nails, 10%.
Cysteine’s high sulphur content makes it important for the cohesion, stability and resistance of keratin, and as a result, that of the hair and nails. It forms disulphide bonds between molecules, acting like glue to keep all the keratin fibres together. Fragile, brittle hair and nails are often the result of bonds between these constitutive cells being too weak. Sulphur and sulphur-containing amino acids thus play a particularly important role in the strength of the hair and nails.
Methyl-sulfonylmethane (MSM), a sulphur donor
Keratin, the structural protein of the hair and nails, contains very high levels of sulphur, mostly in the form of amino acids, such as cysteine, cystine and methionine. MSM is used to maintain normal keratin levels in hair and nails. It helps make cells walls more permeable in order to facilitate the transfer of essential nutrients, thus improving hair and nail quality.
Experiments using MSM containing radiolabelled sulphur (35S) have shown that following ingestion, MSM donates its sulphur to the amino acids methionine and cysteine as well to other serum proteins. In this way, sulphur finds its way to the collagen in skin, joints and blood vessels. It is also incorporated into the keratin in hair and nails1
Brittle hair and nails are among the first signs of sulphur deficiency. In a double-blind, placebo-controlled study, sixteen men and five women were given 3000mg of MSM or a placebo every day for six weeks. The health of their hair (length, shine and diameter) was monitored using standard assessment scales. Significant improvements were observed in the health and appearance of the hair in those subjects taking the MSM, particularly so in terms of length and shine.
In another study of 11 subjects, researchers found significant improvements in the strength and appearance of nails in those subjects taking 3000mg MSM a day for six weeks.
Sulphur-containing amino acids, essential for growth
Cysteine plays an essential role in the protein structure of keratin, the key component of hair and nails. The rate of regrowth, protein synthesis and diameter of the capillary fibre depend on the availability of cysteine. In vitro tests suggest that a reduction in the cysteine content of hair follicles leads to a dose-dependent decrease in the rate of growth and the diameter of the fibre produced. Supplementation with cysteine, in the form of either L-cysteine or N-acetyl-cysteine, stimulates the growth of hair and nails and makes them less brittle.
Taurine is an amino acid stored in the hair bulb. It is derived from cysteine. It is also an antioxidant which helps fight free radicals and ageing. Studies have shown that taurine has a protective effect specifically on the capillary bulb, in particular:
- by combatting the processes that deform and compress the bulb;
- by prolonging the life and growth of the hair.
Silicon gives strength and resistance to the hair and nails
Silicon is a trace element essential for healthy skin and bones. It encourages the formation of collagen which is crucial for the strength and healthy development of epithelial and connective tissue.
The external casing of the hair, which gives it its strength and elasticity, is rich in silicon. Hair with a high silicon content is less likely to fall out and tends to be shinier. Silicon is also the predominant mineral in the nails. Fragile, brittle nails represent a sign of silicon deficiency.
Scientific studies have shown that two to three weeks’ supplementation with silicon makes the nails stronger and shinier. Russian studies suggest that silicon is able to halt hair loss and promote regrowth.
A randomised, double-blind, placebo-controlled study examined silicon’s ability to improve the condition of the skin, hair and nails in women with sun-damaged skin. The women were given 10mg of silicon a day, or a placebo, for 20 weeks. Throughout the study, assessments were made of the health of the skin, hair and nails. Results showed that the silicon made the hair and nails less rough and brittle 2
The effect of choline-stabilised silicon was investigated in a double-blind, placebo-controlled study of 48 women with fine hair. For a period of nine months, they took 10mg/day of choline-stabilised silicon, or a placebo. Results showed the cross-sectional area increased in the supplemented women and their hair was thicker with improved elasticity3
Zinc, essential for the growth and vitality of nails and hair
Zinc is an essential trace element which through its role in keratin synthesis, is fundamental to the growth and vitality of the hair and nails - it is needed in order for keratin and proteins to be synthesised. It promotes bonds between sulphur endings, by protecting them from free radical attack.
Zinc is also involved in the synthesis of essential fatty acids which nourish the tissues surrounding the capillary bulb and prevent them from drying out. It is essential for the mobilisation of vitamin A which helps lubricate the hair, hydrate the scalp and prevent shedding of the skin (dandruff).
The high concentration of zinc found in the scalp suggests the importance of its role there. Zinc deficiency can weaken the hair and nails, manifesting as slower hair growth and weak, brittle and split nails. Some studies show that supplementing with zinc can help treat the nail abnormalities in yellow nail syndrome.
Finally, in cases of male-pattern baldness, it helps inhibit 5-alpha-reductase, an enzyme found in the scalp which causes excess sebum and hair loss.
B group vitamins
Biotin strengthens nails and halts hair loss
Biotin, a B group vitamin, can strengthen hair and nails by promoting cross-links. A number of clinical studies suggest that taking biotin (at a dose of 1-3mg/day) is associated with stronger, thicker nails. Biotin deficiency is predominantly linked to hair loss or alopecia. Weak, brittle nails are common, especially in women with low biotin levels. In a study of 71 patients treated orally with 2.5mg of biotin, among the 45 people whom it was possible to assess at the end of the study, 41 (91%) showed definite improvements in terms of harder nails after 5.5 months’ treatment.4
. Another study conducted in Switzerland of subjects with weak nails showed a 25% increase in nail thickness following 3-6 months’ supplementation with biotin.
Biotin stimulates growth of the hair follicle. In male pattern baldness, taking biotin helps temporarily halt hair loss and gets rid of its dull, brittle and depigmented appearance. It has proven follicle-stimulating and anti-seborrheic effects.
Choline belongs to the family of B vitamins. It promotes metabolism of fats and helps maintain hydration of the hair and nails, but as with many other nutrients, choline levels tend to decline with age.
PABA, or para-aminobenzoic acid
PABA is a natural, water-soluble cofactor of the B group vitamins, as well as an antioxidant that can block the harmful effects of UV rays. It appears to be able to restore colour to grey hair in 10-25% of cases.
Back in 1941, a team of researchers reported that daily administration of 200mg of PABA for two months had produced a marked darkening of the hair in 30 patients with grey hair6
. In an effort to replicate these results, another team of researchers gave 20mg of PABA with 100mg of calcium pantothenate and 50g of brewer’s yeast to patients with grey hair, for a period of eight months. They found that hair colour changed in only two of the 33 subjects tested. 7
. A doctor from Temple University, Philadelphia, followed these investigations with a report describing five cases of significant colour change and hair regrowth in 20 patients with markedly grey hair who had taken 6-24g of PABA a day for other health reasons. He concluded that consumption of 6-24g of PABA per day for at least six weeks restored natural hair colour in 25% of people with markedly grey hair. He did not speculate over the mechanism of action involved but pointed out that the effects were highly variable and might require longer periods of supplementation.
Inositol is involved in the metabolism of fats and improves the health of the skin and hair. It is a constituent of every cell in both the animal and plant kingdoms. Its chemical form is identical to that of a simple sugar except that the atoms are arranged differently. Essential for healthy hair, inositol protects the follicle from cellular damage.
Animal studies have shown that inositol deficiency causes fur loss in mice, as well as retardation of growth. In humans, it can manifest as the onset of baldness.