I was aked this past week whether pumpkin seed oil can increase hair growth. Unfortunately, the evidence is weak because of poor and misleading studies. Therefore, at best, I can say the pumpkin seed oil may have a small effect in helping to grow hair. A 2014 study from South Korea is often cited for evidence that pumpkin seed oil helps grow hair, but I’ll show you that’s not what the poorly designed, misleading study found. I’ll show you that pumpkin seeds and/or pumpkin seed oil has many health benedits (including prostate health) and when combined with other ingredients and procedures can provide benefit to hair growth. And, as a professor of ophthalmology and neuroscience, I’ll mention that pumpkin seeds may help with macular degeneration and glaucoma because they contain nutrients that support eye health, high in vitamin A, lutein, zeaxanthin, zinc, magnesium, antioxidants, and polyunsaturated fatty acids such as DHA.

While the factors contained in NeoGenesis Hair Thickening Serum (HTS), such as the exosomes from dermal papilla cells from hair follicles, have demonstrated effects in growing hair, other factors may work well in conjuction with HTS to enable hair growth. Pumpkin seed oil may be one factor that contributes a small benefit. Let’s have a closer look.

I’ve incorporated pumpkin seeds and their oil in my diet for years. I’ve personally experienced their health benefits, and so have a number of people whom I’ve recommended pumpkin seeds be added to their diets. A real-world endpoint indicating the health benefits of Styrian pumpkin seeds is that older men don’t awake at night having to urinate. Pumpkin seeds, especially the hullless type from Styria, Austria (see Kang et al, 2021) have been found to reduce benign prostate hyperplasia (BPH). These types of pumpkin seed are available from Lark Ellen Farms in Ojai, CA, and the oil is available from La Tourangelle in Woodland, CA. I’m sure there are other suppliers of quality products (remember, expensive oils are frequently diluted with cheaper oils) other than the two that I use.

Let’s have a quick look at the often cited study by Cho et al (2014) that claims pumpkin seed oil helps hair growth. The study had a randomized, placebo-controlled, double-blind, controlled design. These words impress some people. Even though nearly everything we know about the world, whether it is physics, chemistry, biology and medicine, is through observational studies, the mantra these days in medicine is that the only good evidence is through studies that are randomized, placebo-controlled, double-blind, controlled design. However, as Judah Pearl, Ph.D., professor at UCLA has written in his book entitled, “The Book of Why,”

“”Correlation is not causation.” This mantra, chanted by scientists for more than a century, has led to a virtual prohibition on causal talk. Today, that taboo is dead.” Judah Pearl, Ph.D., UCLA

My point here is that there are many methologies for acquiring data and knowledge, and just because something is a randomized, placebo-controlled, double-blind, controlled design, doesn’t mean the study is of value. As I’ll show in the “pumpkin seed oil” study, one that is a randomized, placebo-controlled, double-blind, controlled design, the study is pure dross in terms of what the authors intended to study. Nonetheless, there are some things to learn from the study. Let’s have a quick look at the study.

Here’s what the study claims: After 24 weeks of treatment with pumpkin seed oil, patients with mild to moderate pattern hair loss saw a significant increase in self-rated hair growth and satisfaction scores compared to the placebo group (the placebo was poorly defined). And remarkably, what they falsely call the “pumpkin seed oil group” saw a 40% increase in hair count. Considering human hair loss studies, a 40% increase in hair count over 24 weeks is an outlier. Remarkable!

However, reading the study reveals problems, big problems. I always teach my students that one of the questions they must ask about a study is, “compared to what.” So, let’s look at what was being compared in the study. First, the Korean study states that patients were treated with a health supplement containing pumpkin seed oil (and the supplement company funded the study), but a number of other ingredients are contained in the supplement. In other words, the study wasn’t done using pumpkin seed oil by itself as the study suggested. Second what was the active compared to? The study authors say the active was compared to a placebo, but they don’t define the placebo. I ask therefore, how much hair growth can we attribute to pumpkin seed oil? How much hair growth can we attribute to the supplement’s other ingredients and the combination of the ingredients? And is pumpkin seed oil effective in reversing hair loss at a level of 40% increase in hair counts?

Now let’s look at the data. The graph reports percentage differences from the base (100%). That’s 100% at baseline, and about 140% at 24 weeks. But the variability is huge, about 50%. And look at the absolute numbers, i.e. the change in hair counts from base to 24 weeks:  6.2 ± 6.5 (treated) versus 1.8 ± 6.2 (placebo) per unit area measured. The standard deviation is used instead of the standard error of the mean (SEM), and is larger than the mean. Something is likely wrong with these data. The authors appear not to know proper statistical methology. This is highlighted in the next graph.

Now look at measures of hair thickness. Placebo and treated are the same after 24 weeks, and both changed by over 300% in just 24 weeks. Wow! Take a placebo and increase hair thickness by 3X. Let’s all take placebos. Obviously, these data are bogus.

Looking more closely, the second figure shows us that in 24 weeks, the pumpkin seed oil group saw hair thickness increase ~360%. And the placebo group was 350%. The delta hair thickness from baseline to 24 weeks was 0.34 ± 0.03 for the treated versus 0.34 ± 0.02 for the placebo. That’s one heck of a placebo! Many factors contribute to hair growth, including the seasons of the year. What accounted for the increased hair thickness in the treatment and placebo groups? We just don’t know.

So is pumpkin seed oil alone as good as Finasteride alone for growing hair? The short answer is no. Finasteride is a synthetic compound that acts to directly inhibit 5-alpha reductase. Finasteride, once metabolized in the body, directly inhibits 5-alpha reductase at the biochemical level. In contrast, pumpkin seed oil might not directly inhibit 5-alpha reductase. Rather, pumpkin seed oil might indirectly inhibit 5-alpha reductase by reducing inflammation.

Pumpkin seed oil contains many phytosterols as shown in Table 1 (from Kang et al, 2021). These phytosterol compounds have anti-inflammatory effects. β-Sitosterol, for example, is a well known anti-inflammatory.

Inflammatory, damaged tissues release signaling molecules that recruit inflammatory cells to an injury. This process has evolved to fight infection. Hormones, such as DHT, are also involved in healing. When these signaling proteins recruit inflammatory cells to arrive at damaged tissue, expression of the hormone DHT (and the 5-alpha reductase enzyme) occurs at the same sites. The increase in 5-alpha reductase and DHT are responses to the inflammatory process to help dampen inflammation. Therefore, if pumpkin seed oil (PSO) reduces inflammation, and dampens pro-inflammatory signaling that recruits inflammatory cells to our damaged tissues, PSO may also indirectly reduce 5-alpha reductase expression and thereby DHT. This would happen because if there aren’t any signaling molecules turning on 5-alpha reductase, testosterone won’t convert into DHT in those tissues.

Finasteride is a competitive inhibitor of the type II and III isoenzymes of 5-alpha reductase. This difference, direct versus indirect 5-alpha reductase inhibition, is probably why those consuming pumpkin seed oil don’t report the same psychological and sexual negative side effects as those using Finasteride, despite both reducing 5-alpha reductase expression and therefore DHT levels.

Chronic scalp inflammation is closely linked to hair loss through a inflammatory infiltrate in the blood vessels feeding the hair folicles. Chronic inflammation promotes the formation of arterial plaque (atherosclerosis) in the vessels supporting our hair follicles. Over time, this arterial plaque builds up and leads to scarring and arterial calcification. This is the so-called “hardening of the arteries.” This calcification also occurs in the blood vessels supporting our scalp hair follicles. The end effect: reduced blood flow and nutrient/oxygen delivery to the scalp hair follicles – causing our follicles to miniaturize, shrink, and eventually disappear.

Important to delivering nutrients from the blood vessels to the tissues, including hair follicles, is normal functioning of nutrient-transporters. The transporters actively carry the nutrient from the blood vessels into the the tissue. And what does inflammation do to the transporters? The transport activity is negatively regulated by inflammatory cytokines (Seno et al, 2004). If we want to prevent or reverse hair loss, we need to reduce arterial plaque build-up and inflammation in our blood vessels. Pumpkin seed oil is one of many things we need to consume to help do this.

As Knussmann et al (1992) have stated, “The widespread assumption that androgen levels are in general elevated in bald-trait men must therefore be rejected.” Rather, in balding, young men, “significant values were observed in the case of the metabolic rate of dihydrotestosterone/testosterone and the proportion of free to total testosterone. Evidence suggests that balding is a more complicated result of hormonal imbalance. Looking beyond DHT and considering blood hormonal profiles, hair loss is closely connected to a few different hormonal imbalances. These hormonal imbalances vary based on the age, gender, and type of hair thinning from which a hair loss sufferer has. It’s complicated, for sure. But these different hormonal conditions all are suggestive of one thing, namely systemic inflammation. For example, according to the studies by Sanke et al (2016), “Men with early AGA could be considered as male phenotypic equivalents of women with PCOS.”  People with PCOS have higher levels of inflammatory markers such as C-reactive protein (CRP), white blood cells (WBCs), and inflammatory cytokines. This inflammation can lead to polycystic ovaries producing androgens.

To summarize, although the positive effects of pumpkin seed oil on hair growth have been overly hyped because of flawed studies, pumpkin seed oil has benefits to the body and likely provides benefit to the scalp and to growing hair through its anti-inflammatory effects, which then controls DHT levels in the hair follicle.