Table 5.

Natural methods for preventing hair loss

Onion juice	Though the exact mechanism of action towards hair growth is unknown this natural product is quite popular for preventing hair loss purposes. The only patient compliance is the unpleasant odor of it. Presence of sulfur and phenolic compounds are responsible for hair growth purpose. Topical crude onion juice was applied in 62 patients and after 8 weeks it was reported that improvement was seen in the patients [76]
Rosemary oil	Rosemary (Rosmarinus officinalis L.) herb has different useful properties such as antioxidant, antibacterial, antifungal, and anti-inflammatory. It enhances microcapillary perfusion which improves hair growth. A comparative study was carried among 100 androgenetic alopecia patients with topical rosemary oil lotion (3.7 mg/mL) applied daily and topical 2% minoxidil. A standardized professional microphotographic assessment of each volunteer was taken at the initial interview and after 3 and 6 months of the trial. It was seen in both groups it enhanced the hair count after 6 months and the only common adverse effect reported was scalp itching, more frequent with Minoxidil use [77]
Saw Palmetto	SP (Saw Palmetto) is a competitive, nonselective inhibitor of both forms of 5α-reductase. SP blocks nuclear uptake of DHT in target cells and decreases DHT binding to androgen receptors by approximately 50%. The SP extract proliferates 3α-hydroxysteroid-dehydrogenase activity and enhances the conversion of DHT to its weaker metabolite. Prager et al. [78] tested on 26 androgenetic alopecia patients treated with either 50 mg of oral β-sitosterol and 200 mg SP and it was reported 60% improvement in hair loss but has some side effects including appetite, flatulence, and diarrhoea. Another study was carried out with SP as a topical agent. Evaluating the hair growth effect of 3.3 mL topical SP serum applied for 4 weeks and 2 mL lotion for 24 weeks, in 50 men having AGA and reported increased average and terminal hair counts at 12 and 24 weeks [79]
Pumpkin seed oil	Pumpkin seed oil (PSO) contains phytosterols which are a 5α-reductase inhibitor that prevents the conversion of testosterone to active dihydrotestosterone (DHT) and thus improves the hair growth [80]. A comparative study of 400 mg of oral PSO daily to placebo for 24 weeks in 76 patients with AGA verified enhanced in hair count of 40 versus 10% with placebo. PSO is a promising treatment for AGA involving the vertex but failed on frontal variants
Procyanidin	Topical 1% procyanidin B2, derived from apple juice, reported significant improvement in total and terminal hair counts at 4 months and 6 months in 29 patients having male pattern alopecia compared to placebo [81]. Procyanidin 0.7% used to treat 43 men with AGA also established enhanced hair growth counts (3.3 vs. − 3.6 for placebo) after 6 months, with a total increase of 23 hairs/cm2 after 12 months [82]
Garlic gel	A trial was conducted of 40 alopecia patients with topical 5% garlic gel in combination with betamethasone was evaluated in comparison to placebo. After 3 months a positive response was observed in 95% of those treated compared to 5% with placebo [83]
Capsaicin	Oral capsaicin 6 mg and isoflavone 75 mg daily for 5 months improved serum IGF-I in patients with AGA. In AGA specifically, 88% observed hair growth was seen in that treatment [84]. Another research showed that topical 0.01% raspberry ketone (structure similar to capsaicin) regulates IGF-I and stimulates hair growth in 50% of patients [85]
Caffeine	Caffeine enhances cellular proliferation, counteracts the inhibitory effects of testosterone on hair growth, promotes hair shaft elongation, extends anagen duration, and stimulates hair matrix keratinocyte proliferation [86]
Amino acids	Oral l-cystine (70 mg) in combination with retinol was assessed for the treatment of diffuse alopecia and resulted in enhanced hair density and anagen rate [87]. Oral l-cystine was also trailed in combination with histidine, copper, and zinc is taken 4 times daily which results in improved mean change in total hair count after 50 weeks) in 24 patients having AGA [88]
Curcumin	A 5% topical hexane extract of Curcuma aeruginosa (CA) was compared to placebo, 5% minoxidil. On photographic review, combination therapy and 5% minoxidil showed significant improvement than single treatment while the subjective valuation of hair regrowth was only ominously enhanced in the combination group