Michael Pollan says broccoli is better than any supplement — here's why

The author of "The Omnivore's Dilemma" says go spend your money on a good knife for chopping veggies, rather than buying pricey supplements.

• Michael Pollan has been studying America's unhealthy food system for nearly two decades.
• Vegetables are some of his favorite foods. 
• He loves brassicas like broccoli, which scientists suspect have anti-cancer properties. 

It's no secret that Michael Pollan loves plants. He's been encouraging folks to eat more real food — and especially veggies — for basically two decades.

The author of "The Omnivore's Dilemma" and "In Defense of Food" knows that vegetables aren't just great diet staples. In the right quantities and forms, they can be like preventative medicine, and may perform better at keeping people healthy than pricey supplements.

"It's much better to get your vitamins from food," Pollan told Business Insider, ahead of the release of his latest food system documentary, Food, Inc. 2 (out Friday, April 12).

"Our bodies evolved to get nutrients from food, not from pills," he said. "So it's no wonder that supplements generally don't work, unless you have a very specific deficiency."

His stance, while perhaps a bit simplistic, is also a pragmatic one that many doctors, nutritionists, independent supplement researchers, and leading longevity experts generally endorse.

Itching to add a new supplement to your diet? Try broccoli.

Top of mind for Pollan when he thinks about the health-boosting benefits of eating more plants is a family of cruciferous vegetables called brassicas, or cole crops.

These are some of the stockiest, crunchiest plants you can find in the grocery store. They include cabbage, collard greens, kale, cauliflower, broccoli, and Brussels sprouts, and they're great for improving circulation and blood flow, as well as fighting off many age-related diseases.

Scientists suspect that a key reason broccoli eaters tend to have lower rates of certain forms of cancer comes down to a group of sulfur-based chemicals inside the brassicas called glucosinolates, which give these veggies their bitter flavor. When we chop, chew, and digest cruciferous veggies, these potent chemicals break down into bioactive compounds that are thought to help prevent, and maybe even kill some cancer. But, like with so many other nutrients, squeezing this compound into a pill just isn't the same as consuming it in a whole food.

"When they identified this compound," Pollan said, "and then they put it in a supplement, it did not have the same effect."

Studies have consistently shown that the bioavailability of nutritional supplements (that is, how much of the nutrients our bodies can actually use) can vary widely, from basically zilch to toxic. Because supplements aren't well-regulated, it's often hard to know what you're getting, and it can be near impossible to recognize whether or not the supplements you're taking are helping you out, or just causing more problems for your body.

But we already know that the long-term benefits of eating more vegetables and whole grains can include fewer strokes, healthier hearts, less belly fat, lower odds of developing type 2 diabetes, and less cognitive decline too.

"There are things we don't understand about the structure of food and the relationship of the chemicals within the food that is very important," Pollan said.

Pollan pops one supplement: a multivitamin

In addition to his veggie-rich diet, Pollan does take a multivitamin, "but that's it," he said.

Recent research has suggested that a daily multivitamin might be marginally beneficial for working memory in older adults, but it's not essential.

Scientists still generally agree that no supplement can match what a good diet and exercise routine can do, helping prevent and treat lots of chronic diseases all at once.