Phytochemicals and aging

Dr Merlin Thomas

Merlin Thomas is a physician and a scientist. His research laboratory is at the JDRF/ Danielle Alberti Memorial Centre for the study of Diabetes Complications at the Baker IDI Heart and Diabetes Institute in Melbourne.
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Follow the rainbow

All plant products – fruit, vegetables, nuts, grains, legumes and seeds – contain a number of chemicals (phytochemicals), some of which have been shown to have beneficial properties for health and aging.  The actions of these phytochemicals are becoming clearer as research into nutritional health increases.

However, plants are more than the sum of their known phytonutrients.  Individually, none of these components can wholly explain the benefits acquired from eating at least five serves of fruit and vegetables per day. This is why a good diet beats a handful of tablets every time – the combination of different elements in food; the attention and commitment to a dietary regimen; and certainly more tasty and probably cheaper too. And most of all, because it works, and has done for centuries. Rather than only looking for lycopenes or favoring flavonoids, a simple way to make sure we access all the phytochemicals we need is to follow the rainbow.

Look to fill your diet with every bright color of the rainbow every day.

• Red – lycopenes and ellagic acid.  Tomatoes and watermelon for example.
• Orange and deep yellow – high in beta-carotene. (The darker the color, the more beta-carotene).  Pumpkin, carrot, sweet potato, spinach, kale, red pepper, pawpaw.
• Dark green – vegetables that contain lutein and zeaxanthin.  Kale, spinach and collard greens.
• Blue, purple and dark red – flavonoids, including berries.
• Green, white and purple – cruciferous vegetables are high in sulphurous phytochemicals. The same colors in legumes indicate lignins.

Increase the variety of foods we eat

Many of us get into the habit of eating the same foods – day in, day out. If we routinely find ourselves eating iceberg lettuce, try some new varieties, such as rocket or baby spinach. Instead of potato, try a different colour – maybe sweet potato or pumpkin.

Nutrigenomics is one way to get more selective in our diet

What is nutrigenomics? Different foods interact with specific genes to increase the risk of diseases. Across the population, these genes can subtly differ. These differences can partly explain why our own response to the diet may be different from another person. Some genes, good and bad, just need the right environment to make themselves felt, and finding the right diet is one way to get the balance right. For example, fat in the diet is especially bad for those whose genes mean they can’t handle bad (LDL) cholesterol, but it is less of a problem in those with a strong cholesterol removal pathway.

How does it work? A simple mouth swab or blood tests is all we need. A number of commercial agencies offer this kind of DNA testing. These generally cost between hundreds and thousands of dollars for analysis of a specific set of variations believed to influence disease risk and to be diet responsive.

Does it tell us what best to do? Although nutrigenomics is supposed to provide and individualized diet, for the most part, any dietary recommendations that result from such tests are probably not too different from those suggested in this book. At the moment, the cost of these tests may be greater than their advertised benefits. But this area is constantly evolving.