The Misleading Results Of The Pumpkin Seed Oil-Hair Loss Study

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Pumpkin Seed Oil Can Increase Hair Growth By 40%? Not True.

Is pumpkin seed oil an effective hair loss treatment? In 2014, the answer was yes. Today, we’re not so sure.

2014 was the year a team of Korean researchers published a study on pumpkin seed oil and its effects on pattern hair loss. The study’s results made hair loss headlines across the world.

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.

Most impressively, the pumpkin seed oil group saw a 40% increase in hair count. And when it comes to human hair loss studies, a 40% increase in hair count over 24 weeks is amazing.

For example, a 40% increase in hair count is four times higher than the hair count increases observed in this study on men using 1mg of Finasteride (Propecia) over 48 weeks. That’s 4x the hair count increase, in half the number of weeks!

So does this make pumpkin seed oil the new miracle hair loss supplement?

Not exactly.

What Everyone Missed About The Pumpkin Seed Oil-Hair Loss Study

When we read between the lines, the Korean study states that patients were treated with a health supplement containing pumpkin seed oil… and many other ingredients. In other words, the study wasn’t done on pumpkin seed oil by itself.

This begs the question: how much hair regrowth can we attribute to pumpkin seed oil? How much hair regrowth can we attribute to the supplement’s other ingredients? And is pumpkin seed oil really that effective at reversing hair loss?

This article uncovers the answers. We’ll break down everything you need to know about pumpkin seed oil and hair loss.

First, we’ll dive into the real findings of the pumpkin seed oil-hair loss study (hint: it’s not that pumpkin seed oil regrows hair).

Secondly, we’ll uncover the mechanisms by which pumpkin seed oil might reverse hair thinning (and compare its side effects against those of Finasteride).

Finally, we’ll take into consideration all the evidence and determine whether we should include pumpkin seed oil (topically or internally) in our hair loss regimen.

What is Pumpkin Seed Oil?

Pumpkin (Cucurbita pepo) is a cultivar of the squash plant and is native to North America. While most people in the US consume pumpkin seasonally during Winter, pumpkin seeds are often accessible in health stores year-round and considered a “healthy” snack.

Pumpkin seed oil is usually extracted by pressing roasted seeds of the Styrian pumpkin, a variety of pumpkin native to Austria. This thick oil is green or red in color and has a nutty taste often used in salad dressings, desserts, or even cooking oils.

Only recently have researchers started studying the science behind pumpkin seed oil and how it may improve our health, heart, and hair.

But are pumpkin seed oil’s hair benefits you read about on other sites real… or overstated?

The Real Results Of The Pumpkin Seed Oil-Hair Loss Study

Let’s dig deeper into that 2014 pumpkin seed oil-hair loss study.

The design: the study’s investigators performed a randomized, placebo-controlled, double-blind study in which 76 male patients with mild to moderate pattern hair loss were divided into two treatment groups.

One group received a placebo, and the other group received 400mg of pumpkin seed oil daily. These two groups were followed for 24 weeks and the researchers evaluated during which the researchers examined four outcomes of scalp hair growth:

1. Standardized clinical photographs of the scalp
2. Patient self-assessment scores
3. Scalp hair thickness
4. Scalp hair counts

The results: a 40% increase in hair count for the pumpkin seed oil group versus only a 10% increase in hair count for the placebo.

Even the photos show, at a minimum, signs of increased hair density.

But when we take a closer look, we can’t actually attribute all this regrowth to pumpkin seed oil.

In fact, it’s uncertain whether we can attribute any of this regrowth to pumpkin seed oil.

The Pumpkin Seed Oil Study Didn’t Actually Study Pumpkin Seed Oil… It Studied A Supplement Called “Octa-Sabal Plus”

Octa-Sabal Plus isn’t pumpkin seed oil. It’s a Korean health supplement.

One capsule of Octa-Sabal Plus contains 100mg of pumpkin seed powder – not oil. Additionally, Octa-Sabal Plus also contains a proprietary blend of:

1. Octacosanols (derived from vegetable powder)
2. Gamma linolenic acid (derived from evening prim rose powder)
3. Polyphenols (derived from red clover powder)
4. Lycopene (derived from tomato powder)
5. Corn silk extract (from corn silk powder)

These ingredients aren’t just fillers. Just like pumpkin seed oil, they target the myriad triggers of pattern hair loss.

For instance, red clover polyphenols may help reduce excess estrogen (a hormone associated with early onset baldness in men). Lycopene and gamma linolenic acid may decrease certain signaling proteins that increase arterial inflammation (inflammation that typically leads to arterial calcification and even hair loss).

In other words, these “extraneous” ingredients are important. We can’t just ignore them and say their effects are negligible, or that pumpkin seed oil (or powder) was doing all the hair growth heavy lifting.

But that’s not what this study did.

The Study’s Major Flaw: No “Pumpkin Seed Oil Only” Test Group

In order to test pumpkin seed oil’s effectiveness against hair loss, we need to isolate pumpkin seed oil from all other ingredients. No gamma linolenic acid, no red clover polyphenols, no lycopene, and no corn silk extract.

And while the title of the study: “Effect of Pumpkin Seed Oil on Hair Growth in Men with Androgenetic Alopecia…” might lead you to believe the researchers did this, they didn’t.

Instead, they tested 400mg of pumpkin seed powder packaged inside a proprietary blend of other hair loss-fighting compounds. Then they attributed all the treatment group’s hair growth to pumpkin seed oil.

But without a “pumpkin seed oil only” test group, we have no way of knowing how much regrowth was due to pumpkin seed oil, how much regrowth was due to this proprietary blend, or even if these ingredients created hair regrowth synergies and the supplement’s sum is greater than its parts.

It’s important to recognize this. Why? It nullifies the headline, “Pumpkin Seed Oil Increases Hair Count By 40%” – which I’ve read on far too many websites in the last three years.

But beyond the confounding ingredients, there’s something more shocking about the pumpkin seed oil-hair loss study…

Hair Thickness Increased 350%… In The Placebo Group!

In 24 weeks, the pumpkin seed oil group saw hair thickness increase ~360%. And the placebo group? 350%.

It’s an odd finding, and it suggests two things:

1. The power of the placebo effect (this is very real).
2. Seasonality. Since both groups saw nearly the same hair thickness increase, it’s possible this has to do with seasonality – the same seasonality highlighted in our teardown of the rosemary oil hair loss study.

The Placebo Group: Hair Thickness And Hair Count Increased, But Hair Loss Worsened

Despite the placebo group’s 10% increase in hair count and 350% increase in hair thickness… investigators still assessed the placebo’s hair loss as worsening over the 24-week period.

See this graph – which represents the change in investigator’s clinical assessment of each group’s hair loss on a 7-point scale before and after treatment:

It’s a peculiar finding – one that we wouldn’t expect from a group that saw such dramatic increases to hair count and hair thickness.

So… Should We Dismiss The Pumpkin Seed Oil Study Results Entirely?

Not necessarily. In fact, there’s a lot this study did right.

Firstly, the study was conducted on humans – not rats. Far too often everything seems to regrow hair on rats, but rarely do these effects carry over to humans. It’s always encouraging when we see tangible, physical results from human hair loss studies – mostly because they’re much rarer.

Secondly, this study was the first to utilize a randomized, double-blind, placebo-controlled design in evaluating the long-term effects of pumpkin seed oil on pattern hair loss. This type of study design is considered the gold standard when it comes to clinical research. And despite the contradictory assessments of the placebo group (especially given their increased hair count and thickness), the assessors never knew which group they were evaluating.

Finally, this study is the first evidence in human trials that pumpkin seed oil (among other ingredients) may actually slow, stop, or even reverse pattern hair loss.

And when we dig into the supporting evidence, things get even more encouraging.

Boiling Down the Science: Pumpkin Seed Oil’s Hair Regrowth Mechanisms

Pumpkin seed oil is rich in micronutrients – like zinc and manganese – and tocopherols (vitamin E), phytosterols (plant sterols), and unsaturated fatty acids (linoleic acid).

And through these constituents, pumpkin seed oil may help improve pattern hair loss through several mechanisms:

1. Lowering androgen activity (reducing DHT)
2. Reducing inflammation
3. Decreasing atherosclerosis in blood vessels
4. Repleting trace elements necessary for hair growth

Let’s take each one-by-one.

1. Pumpkin Seed Oil Reduces Androgen Activity

The DHT-Hair Loss Connection

Most of us have heard about the connection between hair loss and a male-related hormone known as DHT.

DHT (dihydrotestosterone) is an androgen responsible for a variety of male functions – from sexual development to nervous system functionality. Unfortunately, there’s also a relationship between DHT and hair loss.

Pattern hair loss is association with elevated DHT levels in balding scalp tissues, and many studies show that DHT is at least partially responsible for the miniaturization or “shrinking” of our hair follicles in the scalp.

Testosterone, DHT, And The 5-Alpha Reductase Enzyme

Testosterone is converted to DHT by an enzyme called type II 5-alpha reductase. This enzyme is also found in prostate and scalp tissues.

Type II 5-alpha reductase is what allows DHT to bind to our prostate and scalp tissues. And if we stop this enzyme from activating, DHT can no longer bind to prostate or scalp tissues (which might help prevent more hair thinning).

In fact, inhibiting the type II 5-alpha reductase enzyme is the precise mechanism by which the medication Finasteride (Propecia) works to stop hair loss.

And since the same enzyme (and hormone) are implicated in prostate enlargement, Finasteride is also used to reduce prostate size and improve symptoms in men with benign prostatic hyperplasia (enlarged prostate).

Unfortunately, Finasteride is also associated with a host of undesirable side effects – such as decreased sexual drive and impotence. This is because when we reduce DHT levels in the body beyond a certain point, we begin to shut down the very functions that DHT directly controls (for example – our ability to get and maintain an erection). And people worried about these side effects tend to avoid using Propecia to treat their hair loss.

Pumpkin Seed Oil Decreases 5-Alpha Reductase Activity (And Thereby DHT) – And Might Be A Safer Alternative To Finasteride (Propecia)

The evidence is clear: pumpkin seed oil appears to reduce tissue DHT levels, and without inducing the sexual side effects of Finasteride (Propecia).

One study induced prostatic hyperplasia (an enlarged prostate) in rats by injecting them with testosterone under the skin. The investigators found that pumpkin seed oil prevented prostate enlargement in rats treated with testosterone, likely due to the inhibition of type II 5-alpha reductase. And this study reached a similar conclusion when investigating the effect of pumpkin seed oil on testosterone/drug-induced prostate growth.

The same results hold true in human studies. These researchers evaluated the effects of pumpkin seed oil on symptomatic benign prostatic hyperplasia (again: an enlarged prostate). They determined that 320mg/day of pumpkin seed oil reduced prostate symptoms and improved quality of life after three months of treatment. And all without the sexual side effects.

But why not? If pumpkin seed oil reduces DHT, shouldn’t it also be susceptible to causing sexual problems?

A Paradox: If Pumpkin Seed Oil And Propecia Both Reduce DHT, Why Isn’t Pumpkin Seed Oil Associated With The Same Sexual Side Effects As Propecia?

Let’s review what we know about pumpkin seed oil, Finasteride, and 5-alpha reductase:

1. Pumpkin seed oil reduces DHT – likely by inhibiting the enzyme 5-alpha reductase
2. Finasteride (Propecia) is an FDA-approved hair loss drug that inhibits 5-alpha reductase
3. Finasteride is associated with sexual side effects. Pumpkin seed oil isn’t.

But if pumpkin seed oil and Propecia both reduce DHT, and DHT reduction can cause sexual side effects, then why is only Propecia associated with sexual side effects?

The answer is probably two-fold:

1. Pumpkin seed oil might just be less effective at inhibiting 5-alpha reductase than Propecia.
2. Pumpkin seed oil might inhibit 5-alpha reductase in a different way than Propecia.

Let’s explore that second point for a moment.

5-Alpha Reductase Inhibition: Direct Vs. Indirect

Finasteride is a synthetic compound that acts as a direct 5-alpha reductase inhibitor. In other words, Finasteride – once metabolized inside the body – directly inhibits 5-alpha reductase at the cellular level.

In contrast, pumpkin seed oil might not directly inhibit 5-alpha reductase. Rather, pumpkin seed oil might indirectly inhibit 5-alpha reductase through another mechanism: reducing inflammation.

The explanation is as follows:

In sites of inflammation, damaged tissues release signaling proteins which send inflammatory cells to an injury. This begins the healing process. Hormones (like DHT) are also involved in healing. How? Well, when these signaling proteins signal inflammatory cells to arrive at damaged tissue – we sometimes also see a higher expression of the hormone DHT (and the 5-alpha reductase enzyme) at the same sites. This suggests that 5-alpha reductase and DHT are responses to the inflammatory process.

And by that logic, if we 1) reduce inflammation, or 2) turn off the pro-inflammatory signaling proteins that send inflammatory cells to our damaged tissues, we may also indirectly reduce 5-alpha reductase expression and thereby DHT. Why? Because if there aren’t any signaling proteins turning on 5-alpha reductase, testosterone won’t convert into DHT in those tissues.

This difference – direct versus indirect 5-alpha reductase inhibition) – is probably why pumpkin seed oil users don’t report the same sexual side effects as those using Propecia… Despite the fact that both reduce 5-alpha reductase expression and thereby DHT levels.

Finasteride Directly Inhibits 5-Alpha Reductase. Pumpkin Seed Oil Indirectly Inhibits It. This Probably Explains Why Pumpkin Seed Oil Doesn’t Cause Sexual Side Effects.

To sum up: pumpkin seed oil likely doesn’t directly suppress the 5-alpha reductase enzyme. Instead, pumpkin seed oil likely decreases inflammation by decreasing the expression of inflammatory signaling proteins. And in the absence of those signaling proteins, our bodies express fewer 5-alpha reductase in inflammatory sites. The net result: lower DHT in sites of inflammation.

This is a good thing, because inflammation and hair loss are closely connected… And pumpkin seed oil actually fights inflammation in a variety of ways.

2. Pumpkin Seed Oil has Anti-inflammatory Properties

The Inflammation-Hair Loss Connection

Chronic scalp inflammation is closely linked to hair loss. In fact, it may even be causative.

Chronic inflammation promotes the formation of arterial plaque (atherosclerosis) in the vessels supporting our hair follicles. Over time, this arterial plaque can build up and lead to scarring and arterial calcification.

This calcification also occurs in the blood vessels supporting our scalp hair follicles. The end effect: reduced blood flow and oxygen delivery to the scalp hair follicles – causing our hairs to miniaturize, shrink, and eventually disappear.

If we want to prevent (or reverse) hair loss, we absolutely need to reduce arterial plaque build-up in our blood vessels. Fortunately, pumpkin seed oil might help do this.

Pumpkin Seed Oil’s Antioxidants May Help Reduce Inflammation

Pumpkin seed oil contains antioxidants (substances that prevent the oxidation and degradation of our cells and tissues). Specifically – the antioxidants tocopherols (vitamin E)… And tocopherols are associated with decreasing oxidation and inflammation in certain body tissues.

For instance, a study on rats showed pumpkin seed oil reduces inflammatory mediators similarly to indomethacin (a non-steroidal drug used for arthritis), especially in the chronic phase of inflammation. And this study shows that 100 IU’s / kg of alpha-tocopherols was enough to lower the expression of transforming growth factor beta-1 and oxidative stress – two biomarkers closely linked to inflammation and hair loss.

Pumpkin Seed Oil’s Fatty Acids May Also Reduce Inflammation

Beyond its tocopherol content, pumpkin seed oil is also abundant in unsaturated fatty acids, particularly linoleic acid. And evidence shows that linoleic acid (when it’s not oxidized) has strong anti-inflammatory effects.

For instance, research shows that conjugated linoleic acid inhibits a pro-inflammatory enzyme known as cyclooxygenase (COX-2), and that it’s even as effective at reducing arthritis severity and inflammatory signaling proteins as the popular joint pain drug celecoxib.

Moreover, a recent human study evaluated the anti-inflammatory effects of conjugated linoleic acid in young male subjects performing exhaustive exercise. The subjects who received conjugated linoleic acid showed a significant reduction in inflammatory markers – such as matrix metalloproteinase, high-sensitivity C-reactive protein, and tumor necrosis factor.

Unsurprisingly, all of those signaling proteins are associated with the onset of calcification – the same kind of calcification we see in the scalps of men and women with pattern hair loss.

Which brings us to our third mechanism of action…

3. Pumpkin Seed Oil Reduces Atherosclerosis

We know that chronic, systemic inflammation can lead to the buildup of arterial plaques (atherosclerosis), and that atherosclerosis can lead to arterial calcification, reduced blood flow to hair follicles, and hair loss.

And it’s no wonder there’s a correlation between pattern hair loss and cardiovascular disease. Why? The chronic inflammation that triggers arterial plaque in our scalp blood vessels is also the same chronic inflammation that triggers arterial plaque everywhere else in our bodies – including the heart.

The takeaway: if we want to preserve our heart (and hair) health, it’s critical we prevent arterial plaque build-up.

So can we tie the anti-inflammatory effects of pumpkin seed oil to a reduction in arterial plaque?

Yes! 

This is exactly what a group of investigators sought to accomplish when they studied rats that were switched from a diet high in saturated fat to a diet rich in unsaturated fat.  The findings: the rats eating a diet richer in unsaturated fatty acids decreased both fatty liver disease and atherosclerosis. What’s more, these outcomes were attributed to the anti-inflammatory effects of unsaturated fatty acids and the phytochemicals in pumpkin seed oil.

Numerous studies have confirmed the anti-inflammatory actions of conjugated linoleic acid in arteries and have demonstrated that linoleic acid not only prevents the progression of atherosclerosis, but also induces atherosclerotic regression.

In other words, these fatty acids are pro-heart and pro-hair. And these fatty acids are also carriers of pumpkin seed oil’s rich mineral content – minerals that are required for proper metabolism, cell function, and even hair growth. Which brings us to our final mechanism of action for pumpkin seed oil.

4. Pumpkin Seed Oil Repletes Minerals Necessary for Hair Growth

The Zinc-Hair Loss-Pumpkin Seed Oil Connection

Skin has the third highest abundance of zinc in all body tissues. In fact, zinc is required for the proliferation and differentiation of the cells in the outermost layer of our skin – epidermal keratinocytes. And interestingly, evidence shows that epidermal keratinocytes are partially responsible for hair follicle proliferation. So it’s no surprise that deficiencies in trace elements such as zinc, magnesium, and calcium are associated with a rare form of hair loss called alopecia areata – and may also be involved in the pathogenesis of pattern hair loss.

One study showed that zinc deficiency is associated with patchy and diffuse forms of hair loss in children. And a recent meta-analysis found that people with alopecia areata had lower serum zinc levels compared to healthy individuals.

While the zinc-alopecia aerata connection isn’t totally understood, it highlights the importance of trace minerals for the support of metabolism, hormone synthesis, and even our hair.

The good news: pumpkin seed oil is abundant in these very minerals: zinc, magnesium, iron, and calcium. As a result, consuming it regularly may have a protective effect against nutrient deficiency-driven hair loss.

Pumpkin Seed Oil And Hair Loss: What We Don’t Know (And Why It’s Important)

A lot of people are hyping up pumpkin seed oil up to be a hair loss cure-all. But the evidence is really limited.

For instance, when we delve into the details of the aforementioned Korean study, we find that the supplement they used wasn’t pumpkin seed oil; it was Octa Sabal Plus – a supplement that contains many ingredients (one of which is pumpkin seed oil). And while the regrowth results were promising, these confounding factors make it impossible to tell ow much regrowth to attribute to the pumpkin seed oil, and how much regrowth to attribute to the supplement’s other ingredients.

Additionally, although the authors postulated that pumpkin seed oil’s benefits for reversing pattern hair loss are related to the inhibition of 5-alpha reductase, they never actually confirmed this mechanism of action. That’s a problem. Why? We might be assigning the hair regrowth to the wrong mechanism.

What We Need To Know: Unanswered Questions About Pumpkin Seed Oil And Hair Loss

Future studies on pumpkin seed oil and hair loss should answer the following:

What are pumpkin seed oil’s effects on blood-level and tissue-level DHT? This will give us an idea of pumpkin seed oil’s effects on 5-alpha reductase.

What are pumpkin seed oil’s effects on prostate-specific antigen in their subjects? This will also help us determine whether pumpkin seed oil acts on 5-alpha reductase – or through secondary 5-alpha reductase inhibiting mechanisms (like reducing pro-inflammatory cytokine expression).

How does pumpkin seed oil compare to DHT inhibitors like Finasteride? In the beginning of this article, we did a crude cross-comparison between hair count studies on pumpkin seed oil and Propecia. But that wasn’t very scientific. It’s likely that the major difference in hair counts between studies are due to different counting methods and assessors. We need an actual study to compare the two together.

If pumpkin seed oil inhibits 5-alpha reductase, how does it do it? Again, there might be a big difference between direct versus indirect 5-alpha reductase reduction – which could explain why pumpkin seed oil testers aren’t reporting any sexual side effects.

Is topical pumpkin seed oil as effective as oral pumpkin seed oil for regrowing hair? It’s possible pumpkin seed oil’s linoleic acid and tocopherols might be more effective when applied directly to the scalp. But without a study, we can only take guesses.

Summary: Should We Use Pumpkin Seed Oil?

Based on the evidence, pumpkin seed oil may be a promising hair loss treatment. And its antioxidant, anti-inflammatory, and anti-androgenic properties may be the key its hair-regrowing capabilities. But should we actually include it in our hair loss regimen?

Maybe.

Pumpkin seed oil probably has a protective effect against more hair thinning, since it’s been shown to reduce chronic inflammation and atherosclerosis. These conditions eventually trigger fibrosis and calcification – so anything that can prevent them will help with our hair health.

Moreover, the constituents in pumpkin seed oil such as linoleic acid, phytosterols, and tocopherol may also improve cardiovascular health. And its trace elements such as zinc, magnesium, and calcium – are critical to preventing hair loss due to nutritional deficiencies.

In addition, the phytosterols in pumpkin seed oil have shown to have inhibitory actions on 5-alpha reductase, the enzyme that converts testosterone to DHT. High DHT levels in scalp tissue are correlated with pattern hair loss; therefore, pumpkin seed oil may be a natural DHT blocker with pro-hair effects.

And even though pumpkin seed oil might be anti-androgenic, it doesn’t seem to harbor any sexual side effects. This makes it a potentially better option for anyone concerned about (or even experiencing) the effects of Finasteride on their sex drive.

How To Use Pumpkin Seed Oil For Hair Thinning

There are no strict guidelines on the proper use of pumpkin seed for hair loss. But the majority of studies focus on oral pumpkin seed oil intake. Knowing this, let’s only look at dosages for human subjects.

The study demonstrating the benefits of pumpkin seed oil on enlarged prostates used doses of 325mg daily and found favorable results after 3-6 months of treatment.  Similarly, the 2014 Korean study used doses of 400mg daily for six months of treatment – and these dosages were split throughout the day: two 100mg capsules 30 minutes before lunch and dinner.

It is common to find 1000mg pumpkin seed oil tablets at nutritional stores and pharmacies.  Since pumpkin seed oil is well tolerated without major adverse effects, a dose between 400mg and 1000mg per day is likely to be within the safe range.

If you’re going to try pumpkin seed oil, try it for at least 6 months to observe any appreciable increase in hair growth.

And most importantly, if you’re going to try pumpkin seed oil, make sure you’re buying from brands that are refrigerated and cold-processed. Doing so will minimize the oxidation of its unsaturated fatty acids – which will make these acids even more effective.