by Marion Nestle

Currently browsing posts about: Antioxidants

Nov 19 2007

The (silly) battle of the antioxidants

Which fruit has the most antioxidants? The latest report says blueberries, followed by cranberries, apples, red grapes, and finally green grapes. What? Pomegranates don’t even make the top five? In this case, who knows? The investigators were testing a new assay method and those were the only fruits they examined. Never mind. It doesn’t matter. A fundamental principle of nutrition is variety. In this case, variety means that it’s good to eat different kinds of fruits and vegetables. Each contains its own unique complement of antioxidants and other nutrients and if you eat a variety of foods, you are likely to get all the ones you need and not overdo on any.

Oct 22 2007

Antioxidants: Too much of a good thing?

Evidence continues to accumulate, little bit by little bit, that fat-soluble antioxidants and antioxidant vitamins–in this case, lycopenes, lutein, and beta-carotene vs. vitamin E–interfere with each other’s absorption. Here’s the short description and here’s the original paper so you can see how the little bits accumulate. For me, the take-home lesson is easy: eat food, not supplements.

Aug 11 2007

Can Foods Be Ranked Nutritionally?

A comment posted yesterday under the Label category asks whether it is possible to rank foods: “The idea that I’m trying to express is some measure that shows that 100 calories of, say, broccoli sauteed in olive oil is healthier than 100 calories of shortbread cookies or 100 calories of potato chips, even if they happend to have the same number of fat grams.”

I have philosophical as well as practical problems with this kind of approach. First, the practical: Foods contain 40 to 50 components known to be required in the human diet and hundreds more (antioxidants, for example) that are not considered essential but have effects on health. All foods except sugar–which has calories but no nutrients–have lots of different nutrients, but in different proportions. Once you get beyond soft drinks, the situation gets really complicated. Many groups have taken this on: Center for Science in the Public Interest, Hannaford supermarkets, the Australian Heart Foundation, for example. I think they are way too complicated and the cut points set up a slippery slope. If you rank foods high because they contain vitamins, all companies have to do is add vitamins to their products to make them rank higher.

Philosophically, I much prefer the “eat less, move more, eat lots of fruits and vegetables, and don’t eat too much junk food” approach. Because there are so many different nutrients to keep track of, and because foods have nutrients in different proportions, eating lots of different kinds of relatively unprocessed foods takes care of nutritional needs. Keeping junk foods (highly processed by definition) to a minimum means that you don’t have to worry about the nutritional details and can enjoy what you eat.

Thanks for asking!

Jun 18 2007

Foods vs. Supplements

A writer for a women’s magazine asks: If you want to get more of a specific nutrient (lycopene, for example), is it better to take a dietary supplement or to eat foods containing that nutrient? What benefits do you get from eating a whole food that you might miss if you took a supplement instead?

My response: Unless you have been diagnosed with a vitamin or mineral deficiency and need to replenish that nutrient in a great big hurry, it is always better to get nutrients from foods—the way nature intended. I can think of three benefits of whole foods as compared to supplements: (1) you get the full variety of nutrients—vitamins, minerals, antioxidants, etc–in that food, not just the one nutrient in the supplement; (2) the amounts of the various nutrients are balanced so they don’t interfere with each other’s digestion, absorption, or metabolism; and (3) there is no possibility of harm from taking nutrients from foods (OK. Polar bear liver is an exception; its level of vitamin A is toxic). In contrast, high doses of single nutrients not only fail to improve health but also can make things worse, as has been shown in some clinical trials of the effects of beta-carotene, vitamin E, and folic acid, for example, on heart disease or cancer. And foods taste a whole lot better, of course. For more on this, see chapter 37 in What to Eat on “Supplements and Health Food.”