The Whole Food Story
New Zealand Listener|November 24 - 30 2018
The Whole Food Story

As more of us swallow pills to cover dietary lapses, new research suggests our money is better spent on hero vegetables, nutritionist

Jennifer Bowden

Good news about the health benefits of broccoli, cabbage and cauliflower just keeps on coming.

But, as for the supplements we’re increasingly swallowing in the hope they will make up for our dietary lapses, new research suggests they may be doing more harm than good.

If you’re taking multivitamin, vitamin C and D, beta-carotene, calcium and selenium supplements for heart health or to increase your life expectancy, you’re wasting your time and money. In fact, if taken in combination with statins, antioxidant mixtures and niacin, you’re in danger of shortening your life.

This analysis comes from a systematic review of randomised control trials (the gold standard for proving causation), published in the Journal of the American College of Cardiology in June. It concluded that evidence of the beneficial effects of dietary supplements across all dietary backgrounds wasn’t demonstrated and that current research on supplement use reinforced advice to eat a healthy diet with plenty of plant foods in which many of these vitamins and minerals are found.

The same message can be applied to cancer prevention. The World Cancer Research Fund’s 2018 report, “Diet, Nutrition, Physical Activity and Cancer: a Global Perspective”, reinforces advice to ignore supplements to prevent cancer and to meet nutritional needs through diet alone. The report is the third comprehensive analysis since 1997 of worldwide research on cancer prevention. It notes there is strong evidence that certain supplements can be harmful to health – for instance, high-dose betacarotene supplements can increase the risk of lung cancer in some people.

An earlier review, by British medical research charity Cochrane, found that vitamin E and vitamin A supplements may also be extremely harmful.

The Journal of Cardiology-published review did find, however, that folic acid may have preventive benefits for cardiovascular disease, and teamed with B-vitamins, may help prevent strokes. But the backing for folic acid came with the rider that high folic-acid intake might increase the risk of prostate cancer.

EAT MORE GREENS

Meanwhile, the evidence for a diet full of fruit and vegetables keeps stacking up. Two major studies in 2018 have highlighted the health benefits of cruciferous vegetables. In April, Australian researchers found that women aged 70 and older who ate plenty of vegetables, particularly cruciferous vegetables, had less carotid artery wall thickness. Women who ate three or more servings of vegetables each day had .05mm less carotid artery-wall thickness than those consuming fewer than two servings. Carotid arteries carry blood to the head and a reduction of just .1mm in carotid-wall thickness is associ ated with a 10-18% decrease in the risk of strokes and heart attacks.

Each additional 10g of cruciferous vegetables eaten a day lowers average carotid artery-wall thickness by 0.8%.

In another study, unveiled in July, drawing from data in the US Nurses’ Health Study, American researchers investigating potential links between fruit and vegetable consumption and breast-cancer reduction revealed an 11% lower risk of breast cancer among women eating more than 5.5 servings of fruit and vegetables a day, compared with those eating 2.5 or fewer servings.

Cruciferous vegetables were found to be particularly beneficial in reducing the risk of breast cancer, along with yellow and orange vegetables – more on those later. Previous studies had hinted at a link between breast cancer reduction and fruit and vegetable intake, but this larger study allowed the researchers to obtain statistically significant smaller findings, particularly for individual vegetables.

We’ve known for some time now that fruit and vegetables are good for your heart. However, only recently have the benefits of the various subgroups of fruit and vegetables been revealed.

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November 24 - 30 2018