The Science Behind Rendered
What the Research Says
In May 2024, a team of dermatology researchers at the Alabama College of Osteopathic Medicine published a peer-reviewed scoping review in Cureus (a peer-reviewed, open-access medical journal indexed on PubMed and the National Library of Medicine). The paper examined the existing scientific literature on tallow’s biocompatibility with human skin.
Study: "Tallow, Rendered Animal Fat, and Its Biocompatibility With Skin: A Scoping Review"
Authors: Russell MF, Sandhu M, Vail M, Haran C, Batool U, Leo J.
Published: Cureus, May 24, 2024. Volume 16, Issue 5, e60981.
DOI: 10.7759/cureus.60981
Indexed: PubMed (PMID: 38910727), PubMed Central (PMC11193910)
What They Found
The researchers screened 147 studies across two major medical databases (PubMed and EMBASE) and selected 19 that met their inclusion criteria. They examined five core questions about tallow’s use on human skin: its composition, its benefits, its therapeutic properties, its side effects, and its environmental safety.
Their key findings, in plain language:
Compositional compatibility:
Tallow is rich in triglycerides — specifically oleic acid, palmitic acid, stearic acid, and linoleic acid. These are the same fatty acids found in your skin’s own lipid barrier. The review noted that tallow also contains vitamins A, D, K, E, and B12.
Absorption and delivery:
The skin’s outermost layer (the stratum corneum) is held together by a lipid-rich matrix of cholesterol, free fatty acids, and ceramides. Tallow’s fatty acid composition is structurally compatible with this matrix, which supports its ability to be absorbed rather than sit on the surface. The review noted that fatty acid uptake into skin cells is transport-mediated — meaning your skin has a built-in mechanism for absorbing these specific types of fats.
Natural occlusivity:
The review found evidence supporting tallow’s ability to provide natural occlusivity — forming a protective layer that helps the skin retain its own moisture without blocking it with synthetic barriers. This is functionally different from petroleum-based ingredients, which create a seal on the skin’s surface using molecules too large to be absorbed.
Low irritancy potential:
The research found evidence suggesting tallow demonstrates low irritancy potential when applied topically, making it suitable for use across different skin types.
The gap:
The researchers noted that while there is substantial evidence supporting tallow’s composition and biocompatibility, more controlled human trials are needed. The review called for additional research including case studies, randomised controlled trials, and cross-sectional studies specifically examining tallow as a cosmetic product for human skin.
Source:
Russell MF, Sandhu M, Vail M, et al. Tallow, Rendered Animal Fat, and Its Biocompatibility With Skin: A Scoping Review. Cureus. 2024;16(5):e60981. Published May 24, 2024. doi:10.7759/cureus.60981. Available at: pmc.ncbi.nlm.nih.gov/articles/PMC11193910/
Why Not Petroleum?
Most conventional moisturisers use petroleum-derived ingredients as their base — mineral oil, petrolatum, paraffin. These are byproducts of the crude oil refining process.
Petroleum-based molecules are structurally different from the lipids your skin produces. They’re significantly larger than the 500-Dalton threshold that research identifies as the upper limit for transdermal absorption. This means they sit on the skin’s surface rather than being absorbed into the lipid matrix.
This creates a synthetic seal. It can trap moisture temporarily, but it doesn’t deliver the fatty acids, vitamins, or lipid building blocks that the skin’s barrier actually needs to repair and maintain itself. When the seal is washed off, the underlying skin hasn’t received any of the raw materials it requires.
Tallow works differently. Its fatty acid molecules are structurally compatible with the skin’s own lipid barrier. They’re absorbed paracellularly — through the spaces between skin cells — and integrate into the existing matrix rather than sitting on top of it.
The Fatty Acid Profile
Here’s why the composition matters. Your skin’s protective barrier is built from specific fatty acids. Grass-fed beef tallow contains the same ones in similar proportions:
Stearic Acid (~25% of tallow): One of the primary structural fatty acids in human sebum. Strengthens the moisture barrier and helps regulate the skin’s own oil production. Your skin already produces this in significant quantities.
Oleic Acid (~40–45% of tallow): The most abundant fatty acid in beef tallow and a major component of human sebum. Penetrates into the skin’s lipid matrix rather than remaining on the surface. Helps keep the barrier flexible and supports long-term moisture retention.
Palmitic Acid (~25% of tallow): Another fatty acid your skin produces naturally. Tallow doesn’t introduce a foreign substance — it supplements what your body is already making.
Conjugated Linoleic Acid (CLA): Grass-fed tallow contains significantly higher concentrations of CLA compared to grain-fed sources. CLA is a naturally occurring fatty acid found in the fat of ruminant animals raised on pasture.
Fat-Soluble Vitamins (A, D, E, K): Naturally present in grass-fed tallow. These vitamins are absent from petroleum-based skincare products entirely.
Why Grass-Fed Matters
Not all tallow is the same. The fatty acid composition of tallow varies significantly based on what the animal ate.
Cattle raised exclusively on pasture (grass-fed and grass-finished) produce tallow with a meaningfully different nutrient profile compared to grain-fed cattle. Research indicates grass-fed tallow contains higher concentrations of omega-3 fatty acids and significantly more conjugated linoleic acid (CLA) than grain-fed alternatives.
Rendered uses only 100% grass-fed and grass-finished beef tallow. The sourcing isn’t a marketing label — it’s a formulation decision. The fatty acid profile of the tallow determines how the product performs on your skin.
5,000 Years of Use
Tallow isn’t a trend. It’s one of the oldest skincare ingredients in recorded history.
Sumerians used animal fat in soap-making as early as 3,000 BCE. The Ebers Papyrus — an Egyptian medical text dating to approximately 1,500 BCE — contains recipes for balms using animal fat mixed with honey. Chinese archaeologists discovered a 2,700-year-old bronze jar containing a nobleman’s face cream made from animal fat and moonmilk. Romans applied tallow after bathing. Native Americans used buffalo and bear tallow to protect skin from sun, wind, and cold. Medieval Europeans relied on it for chapped skin. Victorian Londoners purchased “bear’s grease” — likely rebranded pig tallow — as a premium grooming product.
The shift away from tallow happened rapidly. In the mid-20th century, synthetic preservatives, petroleum-derived emollients, and mass-manufactured moisturisers replaced animal fats in commercial skincare. A product used consistently for millennia across every major civilisation was displaced in less than 50 years.
Rendered exists to bring it back — formulated specifically for men, with nothing added that doesn’t belong.
The Rendered Formula
Six ingredients. Every one of them does a job. Nothing added that doesn’t belong.
1. 100% Grass-Fed & Finished Beef Tallow — The foundation. Fatty acids that mirror your skin’s own sebum.
2. Organic Extra Virgin Olive Oil — Adds oleic acid to reinforce the skin barrier. Used on skin for thousands of years across every major civilisation.
3. Organic Golden Jojoba Oil — Structurally closer to human sebum than almost any other plant oil. Reinforces the tallow base and helps the formula absorb without residue.
4. Organic Sweet Orange Essential Oil — Cold-pressed from the peel. Provides a clean, natural citrus scent without synthetic fragrance.
5. Organic Bergamot Essential Oil — Cold-pressed citrus oil. Complements the sweet orange for a subtle, masculine scent that fades quickly after application.
Read the whole label in five seconds. That’s the point.