L‐Carnitine–L‐tartrate promotes human hair growth in vitro

Abstract

The trimethylated amino acid l-carnitine plays a key role in the intramitochondrial transport of fatty acids for beta-oxidation and thus serves important functions in energy metabolism. Here, we have tested the hypothesis that l-carnitine, a frequently employed dietary supplement, may also stimulate hair growth by increasing energy supply to the massively proliferating and energy-consuming anagen hair matrix. Hair follicles (HFs) in the anagen VI stage of the hair cycle were cultured in the presence of 0.5-50 microm of l-carnitine-l-tartrate (CT) for 9 days. At day 9, HFs treated with 5 microm or 0.5 microm of CT showed a moderate, but significant stimulation of hair shaft elongation compared with vehicle-treated controls (P < 0.05). Also, CT prolonged the duration of anagen VI, down regulated apoptosis (as measured by TUNEL assay) and up regulated proliferation (as measured by Ki67 immunohistology) of hair matrix keratinocytes (P < 0.5). By immunohistology, intrafollicular immunoreactivity for TGFbeta2, a key catagen-promoting growth factor, in the dermal papilla and TGF-beta II receptor protein in the outer root sheath and dermal papilla was down regulated. As shown by caspase activity assay, caspase 3 and 7, which are known to initiate apoptosis, are down regulated at day 2 and day 4 after treatment of HFs with CT compared with vehicle-treated control indicating that CT has an immediate protective effect on HFs to undergo programmed cell death. Our findings suggest that l-carnitine stimulates human scalp hair growth by up regulation of proliferation and down regulation of apoptosis in follicular keratinocytes in vitro. They further encourage one to explore topical and nutraceutical administration of l-carnitine as a well-tolerated, relatively safe adjuvant treatment in the management of androgenetic alopecia and other forms of hair loss.

Indications that topical l-carnitin-l-tartrate promotes human hair growth in vivo

“…This small pilot study, evidently, requires repetition with a much larger n of volunteers and a prolonged observational period. However, the currently available data confirm our in vitro data with organcultured human scalp hair follicles [4], and further support the concept that CT is able to promote human hair growth at a favourable ratio of benefits to risks/undesired effects.…”

“…Recently, we have shown that L-carnitine-Ltartrate (CT) is able to increase hair shaft elongation and prolong anagen by upregulation of proliferation and downregulation of apoptosis in organ-cultured human scalp hair follicles [4]. In order to test whether CT is also able to stimulate hair growth in human scalp hair follicles (HF) in vivo, we have performed a small, double-blind, randomised, placebo-controlled observational study of topical CT administration over 6 months twice a day.…”

Adipocytes in Skin Health and Disease

“…However, fatty acids can provide some energy to fuel hair follicle growth, suggesting that hair follicle cells are capable of b-oxidation. Moreover, Lcarnitine, an essential cofactor for b-oxidation, is capable of prolonging the growth stage of the hair follicle (Foitzik et al 2007) and promotes skin wound healing (Pola et al 1991). Additional evidence for the importance of fatty acid metabolism in the skin is the increased activity of the fatty acid enzyme CPT1 in psoriasis.…”

Hair growth effect of traditional Chinese medicine BeauTop on androgenetic alopecia patients: A randomized double-blind placebo-controlled clinical trial

“…In recent years, pharmacological studies have found various herbal ingredients that are anti-androgenic, inhibit 5αR, promote growth factor expression in hair follicles, regulate the endocrine system and enhance microcirculation (7,8). The dietary supplement L-carnitine induces hair growth in vitro (9), but it is not approved by the Food and Drug Administration. An extract of Grateloupia elliptica has the potential to treat alopecia via the proliferation of dermal papilla, 5αR inhibition, increase of prostaglandin E2 production, decrease of lipopolysaccharide-stimulated pro-inflammatory cytokines and inhibitory activity against Pityrosporum ovale (10).…”