Beard Science
The Ingredients You’re Told Are “Good for Beards” - And Why We Do Things Differently
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Not everything labelled “natural” is automatically well-suited to beard care - and not every oil supports the unique biology of facial hair growth.
From plant oils high in polyunsaturated fats to essential oils with naturally occurring estrogenic compounds, there are ingredients commonly used in grooming products that may not align with beard-supportive goals. Even terms like “fragrance” can legally include a wide range of undisclosed compounds.
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At Hairy Highlander, we take a different approach.
We formulate with intention - selecting ingredients based on their compatibility with beard growth biology, skin comfort, and long-term use. This page explores some of the choices we make behind the scenes, and why they matter.
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what fuels beard growth - and what quietly works against it
​At Hairy Highlander, we believe good grooming starts with understanding the biology behind it. Beard growth is not just about genetics or age - it’s also shaped by hormones, product choices, and environmental influences. Below, we lay out the science behind facial hair growth, highlight what supports it, and explore what may silently interfere.
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what drives beard growth? testosterone & DHT
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The two primary hormones responsible for facial hair development are:
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Testosterone - the foundational male hormone
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Dihydrotestosterone (DHT) - a more potent derivative of testosterone
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DHT plays a particularly important role in beard development. It binds to androgen receptors in facial hair follicles, encouraging the transition of fine, soft vellus hairs into thick, terminal beard hairs.
(Source)
Summary: DHT is a key androgen in the development of secondary male characteristics, including facial and body hair. Reduced DHT activity is clinically associated with sparse or absent beard growth.
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the hidden threat: endocrine disruptors in grooming
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Endocrine-disrupting chemicals (EDCs) can interfere with the body's hormone system. Some can mimic estrogen, while others can block hormones or disrupt normal hormone signalling.
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Research has linked endocrine disruption with serious concerns including:
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Reproductive problems
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Metabolic disorders
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Disruption of androgen and thyroid signalling
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Hormone-sensitive cancers
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Possible carcinogenic effects from certain compounds
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Potential sources of exposure include:
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Synthetic fragranced personal-care products
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Certain plastics and plasticisers
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Pesticides
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Everyday cosmetics and grooming products
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Some chemicals used in fragranced products have attracted particular scientific attention. Certain phthalates can interfere with androgen and thyroid receptors, while some synthetic musks have been investigated as endocrine disruptors and possible carcinogens.
For something being applied directly to the skin every day, that is worth knowing.
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(Source 1) (Source 2)
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fragrance: the unregulated grey area
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When you see the words “fragrance” or “parfum” on a product label, they can legally stand in for a mixture of dozens - even hundreds - of different ingredients. Most of the time, the exact contents of that blend don’t need to be listed.
In the UK, this is allowed under cosmetics law (based on EU Regulation No. 1223/2009). Unless certain known allergens are present in high amounts, brands don’t have to reveal what’s actually inside a fragrance blend - even if the product is labelled “fragrance-free” or “unscented.”
That means masking agents - chemicals used to hide a product’s natural smell - can still be in the formula without being shown on the label.
Sources:
UK Government - Cosmetic Products Regulation Overview
EU Commission - Fragrance Allergen Labelling
A peer-reviewed study published in Environmental Health Perspectives tested 50 everyday consumer products — including lotions, sunscreens, and fragranced personal care items. It detected several endocrine-disrupting chemicals (EDCs), such as phthalates and parabens, in products where those substances were not listed on the label.
(Source)
Summary: A peer-reviewed study detected endocrine-disrupting chemicals (EDCs) — such as phthalates and parabens — in grooming and personal care products that did not list them on the label. These compounds have been associated in other research with hormone interference, including effects on male reproductive hormones.
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essential oils & male hormones
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Some natural essential oils may interfere with hormone balance when used in high concentrations. For example, tea tree and lavender oil have shown potential estrogenic effects in limited studies.
(Source)
Summary: This study observed a correlation between topical use of lavender and tea tree oils and hormone disruption in young males. While more research is needed, it raises valid concerns for men using estrogenic EOs in daily grooming.
At Hairy Highlander, we take a cautious approach. We avoid essential oils flagged for estrogenic potential and instead focus on wild Highland botanicals like Bog Myrtle - chosen for their skin-soothing, natural benefits.
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peppermint oil and beard growth
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Peppermint oil has shown promising results in preclinical studies for supporting hair growth, particularly when applied topically in higher concentrations. Its natural cooling and stimulating effects may help improve circulation around the hair follicles and create a more favourable environment for healthy beard development.
A peer-reviewed animal study published in Toxicological Research found that peppermint oil applied topically at a specific percentage in mice led to significantly enhanced hair growth, deeper follicles, and increased dermal thickness
Summary: A 2014 study in Toxicological Research found that peppermint oil significantly improved hair growth in mice, increasing follicle number, depth, and skin thickness.
At Hairy Highlander, we use peppermint oil carefully and intentionally — in concentrations selected for effectiveness and skin comfort, and always within a formula designed to support beard health, follicle function, and long-term use.
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chaga and hair growth
Packed with powerful antioxidants and rare compounds, wild Chaga is thought to help stimulate the very cells responsible for hair growth, supporting a healthier-looking, fuller beard from the root up. Early lab research shows that inotodiol — a triterpenoid found in Chaga — can boost the activity of key hair follicle cells. Additional studies suggest that Chaga’s compounds may help defend against collagen breakdown, support skin’s natural hydration, and visibly calm stressed or reactive skin — all vital for creating the ideal environment for strong, healthy hair to thrive. These early findings make Chaga a powerful ally in skin-first beard care, especially when slow-infused into nourishing botanical oils.
Summery: A 2018 lab study found that inotodiol, a rare compound found in Chaga, boosted the activity of human hair follicle cells. While the research was done in vitro (in lab conditions), it offers early evidence that Chaga’s compounds may help support healthy hair at the follicle level.
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Summery: A 2023 study found that inotodiol - a rare compound found in Chaga - helped reduce inflammation in skin cells exposed to UV damage and supported the skin’s natural production of collagen and hyaluronic acid. These findings suggest that inotodiol may help calm stressed skin, improve hydration, and support firmness - key factors in healthy-looking skin.
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DHT-blocking oils: great for scalp, maybe not so great for beards
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Some natural skincare oils - including borage seed, argan, grapeseed, sweet almond, and hemp seed - are high in polyunsaturated fatty acids (PUFAs) like γ-linolenic acid, α-linolenic acid, & Linoleic Acid. These oils are valued for their light texture and moisturising qualities, but emerging research suggests they may not optimally support beard growth biology.
In vitro studies have indicated that certain PUFA-rich oils can inhibit 5α-reductase - the enzyme responsible for converting testosterone into dihydrotestosterone (DHT), a key androgen involved in facial hair development. While DHT is often associated with scalp hair loss, it plays a different and essential role in promoting beard density and growth.
(Source):
Summery: This peer-reviewed in vitro study showed that certain polyunsaturated fatty acids (PUFAs) can inhibit 5α-reductase — the enzyme responsible for converting testosterone into DHT.
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To be clear:
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These oils aren’t harmful, and likely pose little concern for men with already full, established beards.
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But for men in the early stages of beard growth - where DHT plays a bigger role - using oils that may interfere with this process could be less than ideal.
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The study examines the effects in vitro (in laboratory settings) and does not address the impact of topical application of linoleic acid on DHT levels in humans.
​More research is needed to understand the full picture, especially in real-world, long-term use. Our focus at Hairy Highlander is to use natural oils that are low in PUFAs, providing unique, valuable beard conditioning while steering clear of oils commonly associated with reduced DHT activity - we prefer a cautious choice to better support beard growth biology.​​
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beard care that works with your body - not against it
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Explore our health-conscious grooming range:
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Disclaimer:
This page is for educational purposes and explores scientific research relating to individual ingredients. Research findings relating to an ingredient do not establish the effects of a finished Hairy Highlander product. Our products are cosmetics and are not intended to treat or prevent medical conditions.
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