"Superfoods" or Nutritional Kryptonite?

Monday, May 14, 2007 - 9:44am

By Krista Scott-Dixon, PhD

Oh, how we love our magic bullets: The pills and potions that promise to "detox" us, cure our raging hangover, tidy our bowels, and suck up the fat from the sweaty cheeseburger we just ate. A popular science magazine I read has an ad that appears in the back of every issue for a contraption that promises fitness in just four minutes a day. The contraption, by the way, costs something like $12,000; but hey, isn't your four-minute fitness worth it? You're a busy person, after all.

There are some great things about magic bullets:

  • You can buy them-you don't need to inherit them or work on them. They seem democratic that way.
  • They'll make up for your indiscretions in other areas. Chug that fourth martini! Indulge in that creamy ranch cheese dip for your sausage pizza! You're worth it.
  • They make things effortless and simple. Why waste time on living healthy when you could pop a pill?
  • You only need one of whatever it is. One thing will solve all your problems. After all, it's magic.

Pseudoscience and false claims about "superfoods"

Not really coincidentally, these features also happen to be associated with "pseudoscience." From the Greek pseudo, or false, pseudoscience consists of false or misleading claims that are not based on reality or evidence-precisely the stuff of which many mainstream fitness and nutrition industry products are made.

In recent years, scientists and supplement peddlers have developed a list of so-called "superfoods." Scientists, who fancy modest, testable claims and boring stuff like evidence and experiments, often use "superfoods" as shorthand for something like "foods that have beneficial effects that exceed their nutritional value." Supplement pushers, who prefer grandiose statements and profiting from bottled junk, are more prone to slapping the "superfood" label on anything that might look and taste gross and chemical enough to feel like it should be healthy.

Real "superfoods"

So what, in reality, is a "superfood"? The list includes the following:

  • Beans and legumes
  • Berries
  • Citrus fruits
  • Cruciferous vegetables, e.g. broccoli, Brussels sprouts, and cabbage
  • Dark chocolate
  • Dark green leafy vegetables, e.g. spinach, kale
  • Nuts, especially walnuts and Brazil nuts
  • Oats and other whole grains
  • Pumpkin and other orange veggies
  • Red wine
  • Salmon
  • Spices such as cinnamon and turmeric
  • Soy
  • Tea, especially green tea
  • Tomatoes
  • Yogurt.

What makes these foods so super? The reasons can be grouped into a few categories:

Aging: Antioxidants and phytochemicals can help

Antioxidants are thought to help the body inhibit the natural "rusting" or oxidation process that comes along with aging. Phytochemicals, which is a fancy way of saying substances found in plants, are hundreds of chemical compounds which may have beneficial effects on the body. The vegetables and fruits listed above, along with Brazil nuts, dark chocolate, tea, and red wine, are high in these compounds (basically, the more colorful the food, the more good stuff it has). Soy's chemical compounds are isoflavones, which appear to have benefits for lowering cholesterol and preventing certain kinds of breast cancers.

For more information on the types of food see the following article from TheDietChannel: 10 Best 'SuperFoods'.

Essential fatty acids are good for you

The body benefits from fats found naturally in plant and fish sources. It especially likes omega-3 fatty acids, which can be found in walnuts and oily fish such as salmon (but also herring, mackerel, and other fatty cold water fish).

Certain bacteria are good for you

We used to think all bacteria were harmful. Now we know that some bacteria live in our body doing good things in places like our intestines. Yogurt is a good source of these probiotics (as well as valuable minerals such as calcium, magnesium, potassium, selenium, and zinc).

Spices to inhibit or prevent disease

Many spices are showing promise as antibacterial, antioxidant, and anti-cancer agents. Cinnamon may help in the treatment of diabetes and turmeric may inhibit the growth of cancer cells. Here also antioxidants and phytochemicals play an important part.

Fiber keeps your digestion healthy

Plant and whole grain sources such as beans and oats have beneficial soluble and insoluble fiber that helps keep digestion humming along, blood sugar levels constant, and blood cholesterol and fatty acids where they should be.

"Superfoods" cannot act alone - a healthy, varied diet is best

Although it is indisputable that all these things are good for you, we do not yet have enough evidence to say definitively that they are "super." Many studies on them have only been done to date in vitro (i.e., in a lab). Although we can observe that, for example, a substance kills cancer cells in a petri dish, we do not yet know that some of these foods will do what we think they might do when actually eaten and digested by humans. We know that it works best to eat a variety of foods, and that these foods cannot do a very good job unless we help them by living a healthy lifestyle as well. All of the broccoli in the world will not make up for a pack of cigarettes. Finally, just because something has benefits in small doses does not mean it will be better in large doses. Nuts and chocolate are calorie-dense so keep portions small. Same goes for red wine and caffeinated green tea.

Bottom line: Eat your fruits and vegetables, especially colorful ones; eat a range of good quality foods (ideally grown locally); be sensible about portion size; and enjoy the occasional fava beans with a good chianti!

Lunn, J. "Facts Behind the Headlines: Superfoods." Nutrition Bulletin 31 no. 3 (September 2006): 171-172.