Phytosterols are compounds found in plants, also known as sterols and stanols, structurally related to cholesterol. There are over 200 types of phytosterols available but the most common phytosterols are β-sitosterol, campesterol and stigmasterol. The idea that phytosterols are effective in the treatment of hair loss has been proposed after scientists discovered their benefits in skincare products.
Phytosterols work in the body by mimicking chrolesterol and preventing the depletion of epidermal keratinocyte membranes, which means that they basically reduce damage from aging processes on the hair and skin. Their main use is in anti-aging products, moisturizing products and wound healing products but more and more companies are developing products based on plant phytosterols that may help with hair loss.
How do Phytosterols reduce hair loss?
Reduction of scalp inflammation
There are several reasons that may explain why phytosterols can be helpful in the treatment of hair loss. One of their main characteristics is their anti-inflammatory potential. Inflammation is often one of the characteristics of the alopecic scalp and several studies have shown that phytosterols have great anti-inflammatory purposes (Aldini et al., 2014)(Othman and Moghadasian, 2011)(Rocha et al.,2016) In vitro studies showed an inhibition of the inflammatory markers such as interleukin-6 (IL-6) ) (Trautwein and Demonty,2007). Their topical anti-inflammatory effects in both acute and chronic inflammatory models have also been demonstrated (Garcia et al.,1999), for example their anti-inflammatory and anti-fungal effects on skin disease like seborrheic dermatitis which would explain their potential to reduce inflammation of the scalp.
Another way phytosterols seem to reduce hair loss and increase hair growth is their reduction of 5-alpha reductase — the enzyme that converts testosterone into DHT. (Liang and Liao, 1995;1997)(Delos et al.,1997)
Plants containing phytosterols, which have been studied for their inhibitory effect of 5-alpha reductase are saw palmetto, sesame seeds and argan oil. In-vitro studies suggested that topical solutions made with these plants showed significant inhibition of 5-alpha reductase in the skin which makes a strong case for phytosterols as DHT blockers.
the participants receiving pumpkin seed oil had a hair count increase of 40%
Pumpkin seed oil was also researched as a 5-alpha reductase inhibitor and has been shown to have anti-androgen effects on rats. In the same study 76 male patients suffering from androgenetic alopecia received 400mg of pumpkin seed oil or a placebo for 24 weeks. The change over time was evaluated and the participants receiving pumpkin seed oil had a hair count increase of 40%. The results could be due to essential fatty acids and phytosterols as both have an inhibitory effect on 5-alpha reductase. (Cho et al., 2014)
Serenoa repens, also known as saw palmetto, is another plant containing fatty acids and phytosterols that benefit the hair and scalp, not to mention the fact that it has been used for centuries as a treatment for hair loss. A study (Fasculo, 2004) used shampoo and topical lotion containing serenoa repens as a treatment for balding participants. The treatment had to be followed for three months. The results showed an increase of 35% in hair density and 67% increase in sebum reduction.
Topical ketoconazole is often prescribed to male pattern baldness patients in order to reduce DHT and inflammation in the scalp. Tosti A. (2006) showed that adding just 0.5% extract of saw palmetto to a ketoconazole shampoo increases the effects of the ketoconazole substance on the scalp significantly.
One of the large components of phytosterols is beta-sitosterols, which may be responsible for reversing hair loss due to their inhibitory effect of 5-alpha reductase enzyme. A study in 2002 (Prager et al.) evaluated certain botanical compounds that had the same effect on 5-alpha reductase as drugs and agents used to treat benign prostatic hyperplasia. Benign prostatic hyperplasia patients are similar to people suffering from hair loss in the sense that in both cases their DHT levels are increased and sometimes finasteride is prescribed to both to reduce DHT. The researchers used liposterolic extract from saw palmetto and beta-sitosterol as treatment for androgenetic alopecia on males between the ages of 23 and 64. The results showed that 60% of the subjects had significant improvements during their final visit and researchers concluded that beta sitosterols and liposterolic extract of saw palmetto were effective as natural 5-alpha reductase inhibitors.
Phytosterols contained by various extracts and oils are also known for their antioxidant effects and this could also contribute to their effect on hair health. (Yoshida and Niki, 2003) The theory that hair falls due to oxidative stress was proposed as early as the 1950s. Free radicals are thought to damage hair either through the body’s metabolism or externally from the environment and with age the body’s mechanism to fight ageing decreases. (Trueb, 2009)
mice treated with lavender oil had significant hair growth compared to the control groups
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One study showed that Arctium lappa, a plant also known as burdock, has an antioxidant effect on hair and may improve hair growth due to its effect on the hair follicles ageing process. The authors of the study concluded that burdock extract, which is rich in phytosterols, may be efficacious in preventing hair loss. (Bae et al.,2014)
The authors concluded that the peppermint oil induces a rapid anagen stage
Lavender Oil, another rich source of phytosterols is known for its benefits in the treatment of hair loss. A study on mice showed that mice treated with lavender oil had significant hair growth compared to the control groups concluding that this oil could be used as a hair growth-promoting agent. (Lee et al., 2016)
Peppermint Oil seems to have similar benefits to hair as it was shown in a 2014 study (Kim et al.) where mice treated with the oil showed prominent hair growth, significant increase of dermal thickness (a decrease in thickness is often associated with androgenic alopecia), increase in follicle number and greater follicle depth. The authors concluded that the peppermint oil induces a rapid anagen stage and can be used as a treatment for hair loss with few to no side effects.
Besides applying phytosterol containing lotions on the scalp, a phytosterol rich diet may also contribute to the health of the hair from within. Phytosterols can be found in plants, especially in wheat, nuts, rice and soy. A diet rich in phytosterols can contribute to better blood circulation, which may inadvertently help with hair loss.
A number of studies have demonstrated the effectiveness of phytosterols in the treatment of androgenic alopecia (AGA). In these studies, the extracts of fruit of the saw palmetto (Serenoia repens) or pumpkin seed oil (PSO) were used as they have a high content of phytosterols (Woelfle, 2010; Cho et al, 2014).
Prager et al (2002) conducted a study on healthy males aged 23-64 years with mild to moderate AGA to investigate the benefit of an extract of saw palmetto and β-sitosterol in treatment of the condition. At the end of the study period, 60% of the subjects from the active study formulation group showed improvement. It was therefore established that phytosterols were responsible for the actions of saw palmetto and are effective 5-α-reductase inhibitors against AGA (Chatterjee and Agrawala, 2003; Prager et al, 2002).
Cho et al (2014) conducted a study to investigate the efficacy of pumpkin seed oil (PSO) on AGA patients. The study was done over 24 weeks on 76 male patients with mild to moderate alopecia. They received 400mg of PSO per day or placebo and results showed a mean hair count increase of 40% in the PSO group as compared to a 10% increase in the placebo group.
Although positive results were reported by Cho et al, the results were only for vertex AGA. Those for frontal AGA were not reported. Furthermore, a study comparing saw palmetto and finasteride in treating frontal AGA reported negative results for saw palmetto (Verma, 2015). This suggests that phytotherapy is a worthwhile treatment for vertex AGA but its effectiveness in the treatment of frontal AGA is still to be established.
Also, although β-sitosterol is an effective inhibitor of 5-α-reductase, it has poor absorption through the intestines (Uphadhyay et al, 2012). However, a strong advantage of phytotherapy over conventional medicine is that no obvious side effects have been observed except in individuals with phytosterolemia, an inherited lipid disorder (Ling and Jones, 1995).
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