The pumpkin seed trial had 1,431 men. Here's what it found

If you're past 50, your doctor has likely told you to eat more fiber and more potassium. You may also have heard that pumpkin seeds are good for a man's prostate. And right now, squash is piled high at most grocery stores.

But the orange in squash barely gets into your blood unless you eat it with some fat. The seed story is only half true, too, and that half is worth knowing before you pay for pills.

So let's look at what the flesh and the seeds really do. The story starts in a cave in Mexico...

In 1966, a University of Michigan archaeologist named Kent Flannery dug into a dry cave in Oaxaca, in southern Mexico. The cave is called Guilá Naquitz. In the dust he found squash seeds, bits of rind and stems.

Some seeds were too big to be wild. They looked farmed. But for years, people fought over how old they were.

In 1997, Bruce Smith of the Smithsonian settled it. He used a radiocarbon test that needs only a speck of the seed. His results ran in the journal Science.

The seeds were up to 10,000 years old. They came from Cucurbita pepo, the plant that gives us pumpkins and zucchini. That is more than 4,000 years before the first dated corn or beans in the Americas.

So squash may be one of the oldest farmed foods on your plate. It belongs to the gourd family, with cucumbers and cantaloupe. And its seeds, called pepitas, are at their freshest right now, in the fall...

The Orange Needs A Partner

Here's the thing. The color in squash comes from pigments called carotenoids. Your body turns some of them, like beta-carotene, into vitamin A. Call them the orange pigments from here on.

The orange pigments melt in fat, not in water. So a plate with no fat at all leaves most of them stuck in the food.

Iowa State University tested this in 2004. Melody Brown and Wendy White fed seven people salads with three kinds of dressing. One had no fat, one had 6 grams of canola oil, and one had 28 grams.

Then they drew blood every hour to see what got in.

Steam Beats A Hot Oven

Heat is the other half of the deal. Cooking softens the walls of each plant cell, and that can help let the pigments out.

But heat can also break them down. In 2018, Caterina Bergantin and her team at the University of Ferrara, in Italy, cooked two kinds of pumpkin for 20 minutes each.

Steamed pumpkin lost less than 10 percent of its beta-carotene and lutein. Pumpkin from a 200°C oven, about 390°F, lost about 30 percent.

That was a lab test, not a test in people. Still, it gives you a plain rule. Steam the squash, then add the fat at the table.

What One Cup Gives You

Take a look at plain canned pumpkin, using numbers from the U.S. Department of Agriculture. One cup holds about 7 grams of fiber and 505 mg of potassium.

A medium banana has about 422 mg. So the can wins on potassium, and it has more than twice the fiber of that banana.

That same cup carries about 1,900 micrograms of vitamin A in plant form. The National Institutes of Health sets a daily goal of 900 micrograms for men and 700 micrograms for women.

Is that too much? No. The upper limit is for the ready-made vitamin A in liver and pills. It does not apply to the beta-carotene in plants.

The seeds are a food of their own. One ounce of dried pumpkin seed kernels holds close to 170 mg of magnesium, plus zinc and protein...

The Seed Trial, Read Closely

In Styria, in southern Austria, farmers have grown pumpkins for their seed oil for about 300 years. Around 1880, a pumpkin turned up with seeds that had no hard shell. That quirk saved long winter nights of peeling by hand, and it is why you can buy green pepitas today.

Those seeds have a long folk tie to men's health. In Germany, a team led by Winfried Vahlensieck put that to a real test.

The trial was called GRANU. It took 1,431 men aged 50 to 80 with urinary trouble from an enlarged prostate.

One group ate 5 grams of pumpkin seed twice a day. A second group took capsules of seed extract. The third took a dummy pill.

After a year, the team counted the men whose symptom score fell by 5 points or more. In the seed group, 58.5 percent got there. The dummy pill group hit 47.3 percent, and the extract did no better than the dummy pill.

Of course, read the fine print. Nearly half the men on the dummy pill got better too. The trial was only partly blinded, and the authors called the seed result clinically relevant but did not claim firm proof. I also could not find who paid for it. It ran in Urologia Internationalis in 2015.

A smaller trial in Korea, from 2009, tried pumpkin seed oil in capsules. Only 47 of the 62 men finished. Scores fell in each group that got oil, but after a year no group pulled clearly ahead of the others. One author worked for a biotech company.

And The Flesh?

I found no trial of squash itself and the prostate. The closest thing comes from the Fred Hutchinson Cancer Research Center in Seattle.

Alan Kristal's team tracked 4,770 men for years. Men who ate four or more servings of vegetables a day had about a 32 percent lower risk of an enlarged prostate than men who ate less than one serving. It ran in 2008 in the American Journal of Epidemiology.

That study watched people. It can't show the vegetables did the work...

Three Things Worth Knowing At The Store

Ten thousand years ago, someone in Oaxaca kept the big seeds and planted them again. That was one of the first steps of farming in the Americas.

You don't need a cave to get the good out of it. All it takes is a squash, a spoon of oil and a few seeds.

So buy one squash this week. Steam it, oil it, and eat it before Friday.

Stay well,
The Healing Plate