A weekly- health led newsletter grounded in evidence based medicine along with prospective randomized controlled trials by medical specialists. Our goal is to help you make sense of complex scientific information and turn it into clear, evidenced based practices you can use to make better decisions about your health and wellness.

THE SCIENCE -- HAIR BIOLOGY

Hair loss is not about strands falling out. At least, not at first. The follicle shrinks. Each growth cycle produces thinner, shorter hair than the last. By the time you see it in the mirror, miniaturization has been running for years.

You are not trying to stop shedding. You are trying to interrupt a hormonal signal that is progressively shrinking the follicle.

The enzyme behind it

Testosterone circulates to your scalp, and an enzyme called 5-alpha reductase (5-AR) converts it into dihydrotestosterone, or DHT. DHT binds to androgen receptors inside hair follicles with about 5x more force than testosterone. That binding tells the follicle to produce progressively weaker hair each cycle.

5-AR has three types. Only Type 2 matters here. It sits in the outer root sheath of hair follicles. We know it is the driver because men born with a genetic Type 2 deficiency do not go bald. Finasteride works on exactly this basis: blocks Type 2 and cuts scalp DHT by around 64%.

What this does to the hair cycle

Hair grows in three phases: anagen (active growth, 2-7 years), catagen (regression, a few weeks), telogen (rest, 2-4 months). In a healthy scalp about 90% of hairs are in the anagen phase at any given time. DHT shortens anagen with each cycle. In a healthy scalp the growing-to-resting ratio runs about 12 to 1. In an AGA-affected scalp it drops to 5 to 1.

That shift is why pattern hair loss looks the way it does. Not bald patches. A slow, diffuse thinning. Fewer hairs in growth. Each one weaker than the last.

THE EVIDENCE -- PUMPKIN SEED OIL

There is one clinical trial that gave pumpkin seed oil its credibility in the hair loss space. Published in 2014 by Cho et al. at Pusan National University. Randomized, double-blind, placebo-controlled. 76 men. 24 weeks. The treatment group saw a 40% increase in hair count. Placebo was 10%. P < 0.001.

It gets cited in nearly every PSO article, supplement page, and wellness newsletter. Including this one, right now.

Here is what most people skip.

Source: Cho et al., Evid Based Complement Alternat Med, 2014. PMC4017725. DOI: 10.1155/2014/549721

Octa Sabal Plus, made by Dreamplus Co. (which also funded the study), contained pumpkin seed powder alongside olive, palm and sunflower extracts, octacosanol, evening primrose, corn silk, tomato lycopene, and red clover. The 400mg PSO figure that circulates everywhere refers to 400mg of this blend. We have no idea what pumpkin seed oil alone contributed.

Hair count going up is real. It suggests dormant follicles re-entered the growth phase. But thickness not changing means structural miniaturization did not reverse at 24 weeks. Those are two different problems. The study addressed one partially and the other not at all.

The trial also showed nothing at 12 weeks. Results appeared at 24. Every person who tried PSO for two months and concluded it did not work ran the experiment for half the required duration.

Source: Published comment on Cho 2014, PMC4396906

 Pumpkin seeds are high in a group of phytosterols called Delta-7 sterols. Their structural similarity to testosterone is what lets them compete for the 5-AR enzyme's active site and slow DHT production. That is the mechanism. Everything else in PSO is secondary.

If you use refined PSO, the compound driving the mechanism has been processed out. Cold-pressed is not a quality preference. It determines whether you are taking an active compound.

Source: Heim et al., Pharmacology and Pharmacy, 2018. Kang et al., Food and Nutrition Research, 2021, PMC8693601

Ibrahim et al. (2021) compared topical PSO directly against 5% minoxidil foam in 60 women with female pattern hair loss over 3 months. Both groups improved significantly. Both performed comparably.

Limitations: No placebo arm, unblinded, only 3 months, PSO concentration unspecified. But this is the only head-to-head comparison between PSO and minoxidil in the literature. For women choosing between the two, this is the relevant data point.

Source: Ibrahim et al., J Cosmet Dermatol, 2021. DOI: 10.1111/jocd.13976

THE PROTOCOL -- WHAT TO ACTUALLY DO

Most natural hair protocols stall not because the ingredients are wrong, but because people skip things no supplement can fix, use a formulation that has been refined into uselessness, or quit at 8 weeks when the study they are citing ran for 24.

Start here.

Ferritin (iron stores)

Target above 70 ng/mL. Standard panels flag normal at 20 ng/mL. That level is too low to support hair growth. Iron deficiency is one of the most underdiagnosed causes of diffuse thinning in women, and it gets missed constantly.

TSH (thyroid)

Even subclinical hypothyroidism causes diffuse shedding with symptoms identical to pattern hair loss. It gets misread as AGA more often than you would expect.

Sleep quality

Chronic poor sleep raises cortisol and suppresses the anabolic hormones that keep the hair cycle running. No supplement substitutes for this. Not even close.

A 2025 double-blind placebo-controlled trial (Piquero-Casals et al., 80 patients, 6 months) tested saw palmetto plus PSO plus pygeum africanum plus L-cystine and found significant increases in hair density and anagen count at both 3 and 6 months. A live trial on ClinicalTrials.gov (NCT06841458) is testing the same stack now.

1.  Saw palmetto, 320mg per day, standardized lipid extract. The strongest standalone natural DHT blocker across the literature. Five RCTs. 60% quality improvement rate in the Evron 2020 systematic review.

2.  Pumpkin seed oil,  cold-pressed only. No refined. No compromise on this.

3.  Minimum 24 weeks before judging anything.  Hair grows about a quarter inch per month. The Cho trial showed nothing at 12 weeks.

Koyama et al. (2016) had 9 men do a standardized 4-minute scalp massage every day for 24 weeks. Hair thickness went from 0.085mm to 0.092mm. Statistically significant (P < 0.05). The mechanism: stretching forces at the scalp change gene expression in dermal papilla cells, turning up NOGGIN and BMP4 while dialing down IL-6 inflammation.

A 2019 survey of 340 AGA patients found 69% reported improvement with 11 to 20 minutes daily over 5 or more months.

It costs nothing. The biology is real. This is the single recommendation in this newsletter that is really implementable on your day to day.

Source: Koyama et al., ePlasty, 16:e8, 2016. PMC4740347

READER'S PULSE

Clinical trials cannot tell you what 6 months of daily scalp massage actually feels like, or whether PSO gave you headaches, or what your hair looks like now versus a year ago. We want to know.

Best responses get published in the next issue under Reader's Pulse.

SAVE THIS -- ISSUE 02 IN EIGHT LINES

Nothing here is medical advice. If you are losing hair, see a board-certified physician. Hair disorders are time-sensitive, and earlier intervention consistently produces better outcomes.

Sources

Cho et al., Evid Based Complement Alternat Med, 2014 (PMC4017725)  ·  Ibrahim et al., J Cosmet Dermatol, 2021 (DOI: 10.1111/jocd.13976)  ·  Drake et al., JAMA Dermatology, 2023  ·  Heim et al., Pharmacology and Pharmacy, 2018  ·  Kang et al., Food and Nutrition Research, 2021 (PMC8693601)  ·  Piquero-Casals et al., Skin Appendage Disord, 2025  ·  Koyama et al., ePlasty, 2016 (PMC4740347)  ·  Evron et al., Dermatol Ther, 2020 (PMC7706486)  ·  StatPearls, Androgenetic Alopecia, 2024  ·  Cleveland Clinic, Dr. Wilma Bergfeld, August 2024  ·  Bayne et al., Br J Dermatol, 1999 (PMID 10583052)