What are anthocyanins and why are purple foods so healthy?

12:26   20 March 2017    1060

Eating a balanced and varied diet, including at least five portions of fruit and vegetables per day, is best for health. But what's so special about purple foods in particular?

Many purple foods contain anthocyanins

All brightly coloured fruit and vegetables contain antioxidants – compounds which play a key role in protecting our bodies – but many naturally purple-coloured foods contain a certain antioxidant called anthocyanin. These are beneficial plant pigments which give fruit and veg their deep red, purple or blue hues.

While studies are ongoing, it’s too early to say conclusively whether anthocyanins deserve the recent media headlines that label purple foods as ‘superfoods’. Previous research has linked anthocyanins to a wide variety of health claims, including increased longevity, cardiovascular health, cancer prevention and dementia.

Which foods contain anthocyanins?

Anthocyanins are found in high concentrations in blackcurrants, blackberries and blueberries, as well as in aubergine (in the skin), red cabbage, cranberries and cherries.

Blueberries



Blueberries are also high in vitamin C, which helps protect cells and aids the absorption of iron, and contain soluble fibre, which is beneficial to the digestive system. Read more about the health benefits of blueberries.

A study in the European Journal of Nutrition found that a supplement containing dried blueberry powder improved brain power in children aged 7 to 10.

Research from Tufts University suggests that consuming a blueberry supplement may be effective in improving or delaying short-term memory loss in rats.

However, the NHS points out that the existing studies into how blueberries might prevent cancer or improve memory have so far relied on small sample groups or animals, and it is not yet clear whether these findings will translate to larger groups of the human population. Read more from the NHS about the nutritional benefits of blueberries.

Pomegranate



Pomegranate is a good source of fibre, and also provides vitamins A, C and E, iron, and other antioxidants such as tannins.

One study found that pomegranate helped to strengthen bones and prevent osteoporosis in mice through decreased inflammation and oxidative stress.

Another study found that consuming 50ml of pomegranate juice per day reduced damage to arteries and cut cholesterol build-up in people with narrowed arteries.

A further study found that a daily glass of pomegranate juice improved blood flow to the heart, resulting in a lower risk of heart attack. However, the NHS points out that as it was a very limited trial these positive results could have been down to chance.

Purple sweet potato



Purple sweet potatoes have recently been in the media spotlight. They are commonly eaten on the Japanese island of Okinawa, which is home to an exceptionally healthy elderly population – with a large number over the age of 100, and rates of dementia reported to be up to 50% lower than in the West. Some scientists think that the large quantities of purple sweet potato in their diet plays a key role in keeping their bodies and brains healthy well into old age. However, to date, there are not many studies into the health benefits of the purple sweet potato, and it’s impossible to say that the Okinawan’s longevity is down to this one food alone.

So should we be eating more purple foods?

There’s no doubt that naturally purple-coloured fruit and vegetables are an excellent addition to a varied diet, but it’s also important to remember that balance is key and include a rainbow of different colours of fruits and vegetables for optimum health benefits.

/BBC/

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