Thinning hair is a normal part of aging for men and women alike. Aging hair follicles, hormonal changes, poor blood flow, chronic inflammation, and aging in scalp skin all contribute. For a thicker, fuller head of hair, it is important to rejuvenate the hair follicles as well as scalp in addition to protecting and nourishing hair strands.
The only living, growing part of your hair is underneath your scalp skin where the hair follicle resides. To increase hair growth, thickness and density, a scalp serum is recommended. Our latest Full Follicle line contains a scalp serum with 14 actives that target the multiple causes of thinning.
Further, the same actives are found in a shampoo and conditioner which are formulated to allow for maximal penetration of actives, and also protect and nourish the thinnest, most damaged and fragile hair strands (learn more).
Today, we will go through briefly all the science behind hair thinning and how actives can target these hair thinning processes. For a more in-depth newsletter, please refer to our Deep Guide (link here), and for a simpler, TLDR version check out our Concise Guide (link here).
From thinning to thicker and fuller hair: Targeting hair follicles
Your genes determine the color of your hair, whether it is straight, helical or wavy, and its length, diameter and density. As we age however, everyone’s hair starts to turn grey and thin or even bald. This is due to changes happening inside the scalp where the hair follicles reside.
At any given time, the hair follicle is in one of three stages that either represents a growth phase (anagen), or a period of non-growth (catagen, telogen). Catagen is a period of regression and telogen a period of rest. Anagen typically lasts 2-8 years with a hair growth rate of approximately 1 cm per month. Catagen lasts for several weeks and telogen lasts for 2-4 months.
(Growth stages reproduced from Jang et al. 2023)
There is a lot going on within the hair follicle. It contains several specialized types of cells. Hair Follicle Stem Cells (HFSCs) are responsible for regenerating the hair follicle for the anagen growth phase. Matrix cells give rise to the actual hair shaft itself. Dermal papilla cells (DPCs) regulate the growth of matrix cells by sending out growth factors and extracellular matrix factors that determine the growth stage. Melanocytes are cells that make the melanin pigments which gives hair its color.
There are also nerve fibers and capillaries that provide blood. The sebaceous gland secretes oily sebum which is what makes your hair and scalp oily. On the skin side of the hair follicle there is also a connective tissue layer which consists of two layers of collagen fibers (Natarelli et al. 2023)
Why hair thins as you age
As you age, there is an increase of hair follicles in telogen versus anagen. The length of the anagen growth stage also decreases. Hair sheds prematurely with aging. Some hair follicles disappear altogether. Loss of melanocytes in the hair bulb leads to a loss of hair color (Buffoli et al. 2014, Natarelli et al. 2023).
Androgenic Alopecia: One major cause is androgens which leads to androgenic alopecia more commonly known as male pattern baldness. Androgenic alopecia is very common and affects nearly 50% of men by the age of 50 years. A potent androgen called dihydrotestosterone or DHT is largely responsible. DHT directly affects DPCs to signal a shortened anagen and a prolonged telogen. DHT also enhances death of hair cells and the hair follicle miniaturizes in a process called follicular miniaturization (Bassino et al. 2020).
With male pattern baldness, there is a genetically determined increased production of DHT in the frontal scalp leading to baldness in a pattern (Liang et al. 2023). The impact of DHT on hair follicles can combine with other aging factors that affect the hair follicle (Deng et al. 2022).
Women are also commonly affected by androgens like DHT although to a lesser extent. Women with androgenic alopecia typically have diffuse apical hair loss and a milder presentation (Villani et al. 2022).
Estrogens (Perimenopause, Menopause, Postpartum): Another major cause is the loss of estrogens during perimenopause and menopause in women. In contrast to androgens, estrogen leads to an increased lushness in hair growth. This is also why there is increased lushness in your mane during pregnancy. Postpartum, this hair sheds as your estrogen levels drop.
After menopause, the levels of estradiol in your bloodstream, which is the primary form of estrogen during your reproductive years, drops to near zero. This drop leads to thinning hair. Estrogen is also important for the integrity of the skin around the hair follicles and so post-menopausal loss of collagen, elastin, and GAGs, and vascularization of the dermis may also contribute to thinning hair (Villani et al. 2022).
Senescence: In addition to sex hormones, natural aging processes contribute. All the cells in your body undergo a process called “senescence” as you age which essentially means a gradual deterioration in a cell’s ability to function, divide, and grow. There is a general decline in HFSC activity and a drop in growth factor production that decreases the ability of the hair follicle to regenerate. Further, in senescent cells, there is a decrease in mitochondrial efficiency which leads to greater production of free radicals with aging (Deng et al. 2022).
Chronic Inflammation: With aging, there is also an increase in chronically elevated levels of inflammatory cytokines which inhibits HFSC function. Inflammation can also impair melanocytes contributing to hair graying as well.
Obesity and psychological stress can also drive chronic inflammation around the hair follicle to drive hair thinning, loss and graying. Chronic stress accelerates hair aging and hair loss through corticosterone which is the major stress hormone in humans.
Corticosterone prevents HFSCs from entering into anagen (Liang et al. 2023). As you age, your skin is also worse at fending off microbes. Demodox mite infestation can increase with aging and contribute to inflammation leading to hair thinning (Liang et al. 2023). Animal studies show that reversing inflammation can lead to some hair regrowth in aged mice (Jang et al. 2023).
Oxidative Stress: With aging, the ability to clear the reactive oxygen species (ROS) declines. Indeed, studies show a buildup of ROS such as hydrogen peroxide in up to millimolar concentrations in white hair shafts. This leads to a loss of melanocytes and a loss of pigment in hair (Trueb 2009). Rapid progression of graying usually occurs in the fifth decade of life. Genetic factors are also heavily involved.
For example Asian and African people have later onset and less grey hair than Caucasians. Environmental factors have been shown to drive oxidative stress and include UV rays, pollution, smoking, nutritional deficiency, emotional factors, and inflammation. Unless the cause is from rare nutritional deficiencies, gray hair has no reliable treatment (Kumar et al. 2018, Villani et 2022).
Reduced blood flow in skin: Dermal microcirculation is essential for hair maintenance. It is important for delivery of growth factors, nutrients, cytokines, other bioactive molecules, and for removing waste metabolic products.
An insufficient blood supply leads to hair follicle diseases. Vascular endothelial growth factor (VEGF) regulates angiogenesis and hair follicle size and decreases with age (Bassino et al. 2020). Blood flow to the dermis decreases with age.
Other factors such as cigarette smoking also cause changes in the microvasculature of the dermal hair papilla. These changes can have negative consequences for hair including thinning and greying (Trueb 2009).
ECM changes: Hair follicle and skin aging is associated with a loss of extracellular matrix (ECM) integrity with aging. Structural proteins in the ECM decline with aging including collagen and elastin.
This drives reduced anchoring of hair in the follicle leading to increased shedding and elevated stiffness in the basement membrane which in turn deactivates HFSCs (Jang et al. 2023). Photoaging leads to elastosis, a condition where degraded elastin molecules accumulate. Elastosis can precede hair thinning and decreases in hair diameter. Bald regions of the scalp often show signs of solar elastosis (Trueb 2009).
Other: Other causes include autoimmune disorders such as Alopecia Arearata, Frontal Fibrosing Alopecia sometimes found in postmenopausal females, drug-induced telogen effluvium, hypo- and hyperthyroidism caused telogen effluvium, and dietary deficiencies in vitamins and essential amino acids histidine, leucine, and valine and non-essential amino acids alanine and cysteine.
Chemotherapy can lead to hair loss and scalp cooling is a technique which mitigates chemotherapy-induced hair loss (Natarelli et al. 2023, Villani et al, 2022).
How to treat hair thinning and hair loss
Prescription Medications: For androgenic alopecia, topical minoxidyl (for men and women) and oral finasteride (Propecia) (for men only) are the only FDA approved prescription medications. Minoxidyl increases blood flow and is anti-inflammatory and anti-androgen. There can be contact dermatitis for minoxidyl including skin itching (Ohn et al. 2019, Naterelli 2023).
About 60% of men with male pattern baldness respond to topical minoxidyl treatment (Liang et al. 2023). Finasteride inhibits 5-alpha reductase, the enzyme that converts testosterone into DHT. Studies show 99% of men with male pattern baldness respond positively to finasteride (Natarelli et al. 2023).
Negative side effects include sexual dysfunction and depression as well as increased risk of prostate cancer. Further, continuous use is necessary as hair regrowth will be reversed when the treatment in stopped. Dutasteride is another 5-alpha reductase inhibitor that is prescribed off-label. (Villani et al. 2022, Liang et al. 2023).
Red Light Therapy for Alopecia: Also known as photobiomodulation therapy (PBMT) or low level laser therapy (LLLT), this is an FDA-approved treatment for hair loss. They do not require a prescription and several devices have shown efficacy.
Hair Transplantation: Hair transplantation therapy can also be employed to help treat bald areas. However, since these hair follicles are still subject to the aged skin environment and hormonal factors, they are subject to some of the same factors that led to hair loss (Jang et al. 2023).
Topical products available over the counter: Many topicals are not FDA approved but have shown efficacy in studies. These include anti-fungals such as Ketoconazole which is a cortisol inhibitor and partly through this inhibition, it can help increase hair density and prostaglandins such as bimatoprost and latanoprost which are popular in eyelash growth serums (Naterelli et al. 2023).
Here we go over the evidence supporting modern topicals that use actives such as peptides, growth factors, caffeine, vitamins, and botanicals which have been shown in studies to achieve clinical results. Where relevant, we detail the actives found in our Full Follicle line (learn more).
1- Peptides: Peptides such as acetyl tetrapeptide-3 can be found in lash, brow, and hair growth serums. Acetyl tetrapeptide-3 is one of the 14 actives in our Full Follicle line.
Acetyl tetrapeptide-3 stimulates DPCs to increase ECM components that improve hair anchoring and reduce hair shedding. This elongates the anagen growth phase and has been shown to stimulate hair growth. In a clinical study of 32 patients with mild to moderate androgenic alopecia, acetyl tetrapepetide-3 with ginseng extract and biochanin A demonstrated comparable efficacy at 24 weeks to 3% minoxidil in increasing terminal hair counts (Lueangaran and Panchaprateep 2020).
In a industry-sponsored clinical study, acetyl tetrapeptide-3 with red clover extract was found to boost the percent of hair follicles in anagen by 15% and decrease hair follicles in telogen in by 52% compared to placebo after 4 months of daily application in lotion form. It was found to have similar benefits in rinse-off form (shampoo and conditioner) as well (Capixyl).
2- Growth factors and platelet rich plasma: The Full Follicle lines uses a growth factor complex of five growth factors (EGF, aFGF, IGF-1, VEGF, bFGF) derived from vegan lab-derived sources.
A diverse array of growth factors regulate the stages of hair growth. Epidermal growth factor (EGF) turns on hair follicle growth to mark the beginning of anagen and turns off to mark the end (Mak and Chan 2002). Deficiency of insulin-like growth factor 1 (IGF-1) is implicated in androgenic alopecia where it is regulated by androgens (Trueb 2018).
During anagen, levels of fibroblast growth factor (FGF) and insulin-like growth factor (IGF-1) stimulate the proliferation of epithelial cells. Vascular endothelial growth factor (VEGF) which is involved in angiogenesis stimulates the proliferation of DPCs (Ohn et al. 2019).
Due to synergies between growth factors, a combination of growth factors rather than a singular one is more effective (Krane et al. 1991). Platelet rich plasma (PRP) is one popular route by which growth factors is delivered to hair follicles as it is rich in growth factors and clinical studies show PRP therapy can increase hair density and diameter in men and hair diameter in women (Paichitrojjana and Paichitrojjana 2022, Natarelli et al. 2023).
However, the expense of PRP and its human source makes synthetic growth factors more popular. A combination of synthetic EGF, FGF, IGF-1, and VEGF has been used to treat androgenic alopecia (Castro et al. 2012, Kapoor et al 2020) and to treat the Alopecia Areata where it to some extent mimicked PRP treatment (Rinaldi et al. 2019).
Clinical and corresponding in-vivo and ex-vivo studies demonstrate that a mix of synthetic IGF-1, aFGF, bFGF, VEGF and EGF increased cell proliferation in DPCs along with corresponding increases in gene and protein expression, as well as greater elongation of the hair shaft (Bio-placenta). Synthetic growth factors have also been shown to promote hair growth in animal models (Choi et al. 2018).
3- Caffeine: Caffeine counteracts DHT induced miniaturization of the hair follicles and is included in our Full Follicle line.
In one in-vitro study using scalp hair follicle biopsies from male subjects, testosterone suppressed growth while caffeine stimulated hair follicle growth. Further, caffeine counteracted the effects of testosterone on the hair follicle (Fischer et al. 2007).
Clinical studies show caffeine can penetrate into hair follicles after topical application. Topical caffeine was found to be more effective than 5% minoxidyl in men with androgenic alopecia. In women, a shampoo with caffeine was found to significantly reduce hair loss (Bansal et al. 2012, Bassino et al. 2020).
4- Vitamins: Vitamins are crucial to healthy skin and hair. The Full Follicle line contains panthenol (Vitamin B5) and biotin (Vitamin B7).
Deficiencies in Vitamin B7 (biotin) has been associated with hair loss. While dietary deficiency in biotin is extremely rare in the US, biotin deficiency can occur in pregnant woman with up to 50% of pregnant women. Hence, biotin is commonly found in hair growth products (Almohanna et al. 2019).
Vitamin B5 (panthenol) deficiency is not associated with hair loss but studies show that the benefits of panthenol to scalp skin and hair follicle health. One study showed panthenol helped the survival of DPCs and outer root sheath cells in the hair follicles and reduced markers for apoptosis (cell death) and senescence (aging) in aged hair follicles.
Panthenol also triggered or elongated the anagen phase by stimulating anagen-inducing factors, B-catenin and versican, and increased VEGF growth factor expression (Shin et al 2021). Panthenol is also common in hair products because it can both coat the hair shaft forming a protective film and penetrate the hair shaft where it strengthens hair.
5- Botanicals and phytocompounds: Botanical plant extracts and phytocompounds have anti-inflammatory and antioxidant activity but also can reduce hair fallout and stimulate hair growth through additional mechanisms (Deng et al. 2022). The Full Follicle line contains Swiss apple stem cells, Red Clover, Rosemary, Ginseng, Eucalyptus, Green tea and Grapeseed.
Certain apple species contain procyanidins that improve hair density, weight, and keratin content (Bassino et al. 2020). Procyanidin B-2 has been clinically shown to improve hair density in androgenic alopecia compared to placebo (Nateralli et al. 2023). These procyanidins are often collected via plant stem cells from the Malus Domestica Apple (Swiss Apple).
Plant stem cells are a new way of harvesting actives in botanicals in large amounts in a cost-effective, environmentally friendly way. Clinically, daily application of a topical solution of stem cell extract reduced hair shedding by 34% after one month of treatment, and by 41% after 2 months leading to a visible improvement in hair density (PhytoCellTech).
Red clover (Trifolium pratense) is a botanical found to help with androgenic alopecia. It contains biochanin A, a phytoestrogen, which inhibits 5-a-reductase activity (Skulj et al. 2019). It is synergistic with acetyl tetrapeptide-3 and in this combination has been found to increase hair thickness and density (Capixyl).
Rosemary is a botanical renowned in traditional medicine. Rosemary is thought to increase hair growth by stimulating microcapillary perfusion and studies show improved blood circulation and vascularity induced by rosemary helps hair follicle regeneration similarly to minoxidyl (Bassino et al. 2020). Clinical studies show comparable efficacy between rosemary and minoxidyl (Naterelli et al. 2023).
Ginseng (Panax Ginseng) is a traditional Chinese remedy which contains saponins, polysaccharides, and phenolic compounds that have demonstrated anti-inflammatory and antioxidant activities. It is also believed to improve blood flow and vasculature, induce hair anagen and have anti-apoptotic effects on outer root sheath keratinocytes. In one study, topical ginseng plus minoxidyl was found to be more effective than minoxidyl alone in promoting hair growth (Bassino et al. 2020).
Eucalyptus is another botanical compound that can improve blood circulation (Mamada et al. 2008). Green tea (Camellia sinensis) has many anticancer and antioxidant benefits from polyphenols such as epigallocatechin-3-gallate (EGCG). EGCG stimulates human hair growth via its proliferative and antiapoptotic effects on follicular dermal papillae cells (Bassino et al. 2020). Vitis Vinifera (Grape) seed extract contains proanthocyanins which have shown promising results for hair growth.
Animal studies show that grape-seed derived proanthocyanins can increase the transition from telogen to anagen and at 3% levels, promoted hair growth to an extent comparable to 1% minoxidyl (Takahashi et al. 1998).
Picking the right shampoo and conditioner
Though hair growth and density relied on the living hair follicles in the scalp skin, a beautiful head of hair also requires maintenance of the visible hair strands. Hair is naturally coated with a waterproof hydrophobic lipid layer made of 18-methyleicosanoic acid (18-MEA) that is bonded to the fiber. In other words, it’s not like oil floating on the surface of the hair you can wash off. It is anchored firmly in place and does not easily wash off (Gubitosa et al. 2019).
However, harsh cleansers as well as other hair treatments such as styling, coloring, perming, blow-drying, and combing with a lot of friction will slowly remove this waterproofing coating and lead to damage to the interior parts of hair leaving it brittle and damaged. So you want to keep cleansing products relatively mild.
This is particularly true if you have chemically treated hair. Finally, you want a conditioner that can restore hair waterproofing to help protect your hair and reverse the damage while also reducing friction during brushing and combing.
Not washing is not an option as this will lead to hair loss. The scalp is a dark, moist and sebum-rich environment. This provides the ideal growing conditions for microbes like Malassezia, a type of yeast. Without cleansing, your scalp becomes infested with microbes like Malassezia which then play a role in dandruff and seborrheic dermatitis which is characterized by red, itchy and flaky skin. This also leads to folliculitis which is when hair follicles are inflamed and infected.
Further, Malassezia oxidizes sebum and these oxidized lipids can be irritating to skin. These factors harm hair growth. Studies show frequent cleansing is necessary for scalp health and hair growth (Punyani et al. 2021). The amount of oily sebum secreted by each person’s scalp differs from person to person. Some people need to wash more, and some less, but overall, we recommend using an effective but mild sulfate-free shampoo such as our Full Follicle shampoo (learn more).
What makes a shampoo mild? Well, look for shampoos formulated for damaged and color-treated hair that contain milder detergents. Most know soaps are bad for hair. However, some synthetic detergents such as sulfates are also harsh. While sulfates like lauryl sulfates like SLS and SLES are popular in shampoo products, they are harsh cleansers and further have a negative reputation of irritancy. Hence, it is a good idea to avoid sulfates and opt for sulfate-free products (Draelos 2010, D’Souza and Rathi 2015, Cline et al. 2018).
Those with thinning hair may also want a hair thickening shampoo that contains additional actives such as caffeine or botanicals that can help stimulate hair growth (Draelos 2010, D’Souza and Rathi 2015). Our Full Follicle shampoo is a scalp stimulating shampoo formulated for thinning, damaged or color-treated hair that contains Acetyl Tetrapeptide-3, Growth Factor Complex (5 GFs), Caffeine, Red Clover, Rosemary, Eucalyptus, Panthenol, and Biotin.
Unfortunately, no matter how mild the shampoo, washing hair basically makes hair rough. That is where conditioners come in. Conditioners can neutralize the negative charge left by anionic surfactants by adding positive charges (cationic syndets and polymers). Damaged hair also has a negative charge because the inner layers of hair behind the damaged cuticles also carry a negative charge. Conditioners contain cationic molecules that bind to the negatively charged damaged hair. Neutralizing this charge will diminish static, frizz and friction.
Panthenol (Provitamin B5) is popular in conditioners as it can stick to hair and absorb into the deeper layers of the hair where it acts as a humectant, holding onto water to help keep hair hydrated. Plant oils and butters contain fatty acids which can also penetrate and coat the hair shaft improving its waterproofing. Hence, conditioners restore the cuticle’s waterproofing and the combability of hair using a combination of polymers, oils, and butters/waxes (Draelos 2010).
Our Full Follicle conditioner uses a silicone-free system powered by ucuuba and murumuru butters as well as panthenol, biotin and swiss apple stem cells (shop now). Please read our newsletter on silicone-free conditioning to. learn why we believe silicone-free systems are. better for conditioning thinning hair (learn more).
References
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