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) are synthetic substances that can interfere with hormone signaling. Some act as estrogen mimics, potentially lowering testosterone and DHT over time. These chemicals are often found in:
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Synthetic fragrances
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Plastic packaging
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Pesticides
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Mainstream skincare and grooming products
(Source)
Summary: EDCs can disrupt natural hormone function and are increasingly linked to reproductive and metabolic issues. Many grooming products contain common EDCs that may affect testosterone and DHT regulation.
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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 - even outperforming minoxidil (a pharmaceutical hair regrowth treatment) in some areas.
Summary: A 2014 study in Toxicological Research found that peppermint oil significantly improved hair growth in mice, increasing follicle number, depth, and skin thickness. It outperformed minoxidil in some areas, suggesting peppermint oil may naturally support the hair growth cycle.
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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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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what we do differently
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At Hairy Highlander, we formulate with biological alignment in mind. Our beard care avoids ingredients that may interfere with hormonal function, and instead supports healthy skin and beard growth using:
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✅ No synthetic fragrance
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✅ No estrogenic essential oils
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✅ No PUFA's in beard oils
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✅ Yes to wild botanical infusions like Chaga and Bog Myrtle
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✅ Yes to biophotonic glass to preserve antioxidant compounds
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want beard care that works with your body - not against it?
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Explore our hormone-conscious grooming range:
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