Vegetables are useless against heart disease? Please.

A curious listener, who may or may not have been my scientist sister (Hi, Pam!) recently forwarded a headline that caught her attention:

"Eating vegetables does not protect against cardiovascular disease, finds large-scale study."

"I thought your readers might come across this and would want to hear your take," she wrote. "At least, I do!"

Just for context, this story was not on some clickbait site but on the blog of Frontiers, a respected science technology platform and publisher. And the headline does faithfully reflect the conclusion of the authors, who found that higher vegetable consumption was not associated with a reduced risk of heart disease or overall mortality. This analysis was done on dietary and health records collected as part of the "UK Biobank" study, which involves almost 400,000 people.  So, these findings are correlations only; they do not prove cause and effect. However, the more expensive and difficult research needed to prove cause and effect often starts with this type of observational finding.

Interestingly, the authors looked at the effects of cooked and raw vegetables independently. Is one form more protective than the other? They found that cooked vegetable consumption was not associated at all with CVD or mortality, but people who ate more raw vegetables were somewhat less likely to develop heart disease or die.

Are raw vegetables better for you?

Proponents of a raw diet might be tempted to seize on this as evidence that cooking destroys the healthful properties of foods and that raw foods are more nourishing. I don't agree with this view. For one thing, raw vegetables can lose up to half of their original nutritional value simply by sitting on your counter for two days—or in your refrigerator for two weeks. Although cooking does involve some nutrient losses, a vegetable that's cooked the day it's harvested could end up retaining more nutrients than a raw vegetable that's been sitting around.

Furthermore, cooking actually makes some nutrients more absorbable. For example, the lycopene in cooked tomatoes is up to 4 times more bioavailable than that of fresh tomatoes.

Nutrients are also lost when foods are dehydrated, frozen, soaked, or juiced. So, when it comes to nutrient losses, unless you can arrange to eat every meal in the field where it was grown, it’s all sort of relative. And even though nutrients are lost, don’t worry—there are still plenty left!

In my view, the biggest nutritional advantage of a raw food diet isn’t the enzymes or the extra nutrients you glean by not cooking your vegetables. Rather, it’s the fact that a raw food diet...

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