Pumpkin seed oil may be a Halloween treat

Some people toss them in the trash. Others roast them for a snack.

The most ambitious among us collect them and press them to produce pumpkin seed oil — an increasingly popular culinary oil that’s also used in supplements for prostate health.

Over a century ago, American farmers noted that when their livestock munched on pumpkin seeds, they seemed to urinate more often. They weren’t the first to notice the seeds’ effects. The Iroquois had long used pumpkin seed as a diuretic, and the Cherokee gave it to children to control bed-wetting, since it seemed to help empty the bladder before falling asleep.

More recently, Europeans began using the bright green oil from crushed pumpkin seeds for prostate health, and in Germany today, the oil is an approved over-the-counter treatment for enlarged prostate glands. In the U.S. too, the oil is one of the top ingredients in herbal blends for prostate health, says Mark Blumenthal, executive director of the American Botanical Council, a nonprofit group based in Austin, Texas, and backed by herbal supplement makers.


But while several companies sell pumpkin seed oil as a stand-alone supplement for prostate health, it isn’t tremendously popular in the U.S., Blumenthal says. That’s because to date, there’s just “a modicum of published, clinical evidence” supporting it, he says.

Much of the evidence on pumpkin seed oil comes from research conducted in Germany over the last 50 years, but just a handful of studies has been published, says Eric Yarnell, a professor of botanical medicine at Bastyr University in Seattle.

Back in the 1960s, a few German studies showed that taking 5 to 15 grams of pumpkin seeds daily for up to a year improved symptoms in patients with benign prostatic hyperplasia, an age-related enlargement of the prostate gland known as BPH. Symptoms include urinating more frequently, a weak or hesitant urinary stream and urinary leaking.

Studies on the subject since the 1960s have been few and far between, but most of them do appear to support those initial findings. In 1990, Swedish researchers gave either a blend of pumpkin seeds and saw palmetto or a placebo to 53 men with BPH. They found that those who received the seed-based treatment were more likely to report stronger urinary flow and less frequent urination compared with those who didn’t receive the treatment. The results were reported in the British Journal of Urology.

In another study, published in a German journal in 1998, more than 2,000 men with BPH took between 500 and 1,000 milligrams of a pumpkin seed oil extract daily for three months. By the study’s end, the men’s average frequency of daytime urination decreased from 6.7 times to 5.2 times, and the average frequency of nighttime urination fell from 2.7 to 1.3 times.

A third study, published in another German journal in 2000, randomly selected among about 500 men to take either 1,000 milligrams of pumpkin seed oil extract or a placebo every day for 12 months. Symptoms improved in 65% of the men who took the oil, which the researchers interpreted as a promising (and statistically significant) result, even though symptoms also improved in 54% of the men who took the placebo.

Such studies suggest that pumpkin seed oil does provide some relief from BPH, but researchers aren’t sure why — or how. One explanation has emerged from the lab: In rats, studies show, the oil stops the conversion of testosterone into dihydrotestosterone, or DHT, a male reproductive hormone that mediates prostate size.

But it isn’t entirely clear that when humans take pumpkin seed oil, their prostates get smaller. Last year, South Korean researchers reported that among 47 BPH patients assigned to take either pumpkin seed oil, the herb saw palmetto, or both every day for a year, all of them experienced symptom relief — but prostate size didn’t change in any of the groups.


Given the paucity of research on pumpkin seed oil, Yarnell says he doesn’t recommend it to patients seeking supplements for prostate health.

But pumpkin seed oil does have other things going for it, he points out. The oil is rich in essential fatty acids — a single tablespoon contains about 4 grams of monounsaturated fatty acids and about 7 grams of polyunsaturated fatty acids, which have been linked to improved cholesterol levels and reduced risk of heart disease. By comparison, an entire medium-sized avocado contains about 15 grams of monounsaturated and 2.5 grams of polyunsaturated fats.

Plus, pumpkin seed oil has a flavor that is nutty and rich. Culinary experts recommend drizzling it over fish, goat cheese, grilled vegetables, soups and even vanilla ice cream.

It may be unproved as a supplement, Yarnell says, but “it certainly is a good food.”