Wimbledon’s favourite fruit serves up health benefits

Scientists at the University of Warwick have discovered that strawberries can prevent the development of diabetes and heart disease. Whilst previous studies have demonstrated the fruit’s capacity to decrease the risk of cardiovascular health problems, the new findings suggest that strawberries can actively stimulate proteins that offer protection against disease.

The team from Warwick Medical School, whose results will be presented at the 16^th biennial meeting of the Society for Free Radical Research International (SFRRI), discovered that extracts from strawberries positively activate the Nrf2 protein. Nrf2 increases antioxidant and other proactive activities, and reduces the risk of cardiovascular problems by decreasing blood lipids and cholesterol.

I spoke to Professor Paul Thornalley from Warwick’s Division of Metabolic and Vascular Health, to find out more about the health benefits offered by Wimbledon’s favourite fruit…

Were you surprised to find that strawberries actively increase our protection against cardiovascular problems?
No, we weren’t surprised because previous research has demonstrated that the prolongued consumption of strawberries will decrease cholesterol and triglyceride levels in the blood. Our research, though, has identified a mechanism that likely contributes to this, and we have screening technologies such that we can now, in principle, identify the best varieties of strawberries and the best ways to process, preserve and maximise their health benefits.

Is this effect unique to certain strawberries, or is it common to all strawberries?
The compounds that produce this effect are likely to be found in most, if not all, varieties of strawberry, but they will vary depending on certain factors such as the particular variety, how they are cultivated and how they are processed. It is important for us to optimise our study in this respect so that we can get the most out of the health benefits that strawberries offer.

How much do you know about the mechanisms involved in this process?
Well, our work focuses on a protein that regulates a protective gene expression called Nrf2, and we want to use a screening technology to study its activation. This protein decreases cholesterol and lipid content in the blood, and raises antioxidant defences that protect us against oxidant damage. It can also affect certain aspects of glucose metabolism that in the longer term, help to resist the development of diabetes.

Are strawberries unique in their capacity to activate beneficial proteins, or do other foods operate in similar ways?
There are similar compounds in other fruits and different types of vegetable – particularly brassica vegetables – but strawberries represent a particularly rich source of these compounds. They are a favourite fruit for consumption, particularly during the summer months, so this news will probably be well received by many people. Strawberries represent a particularly tasty way to get health benefits.

But sadly, this is not also the case with cream…
The clinical studies that have been conducted only looked at the effects of the addition of strawberries to the diet. One wouldn’t want to add a lot of cream because this would increase the cholesterol and lipid content of that diet, thus offsetting the benefits that the strawberries provide. The idea is to have less cream or no cream at all, such as in a glass of fruit juice. This way, you will get the maximum benefit.

So you don't have any plans to test diehard Wimbledon enthusiasts to see whether they are less susceptible to diabetes and heart disease?
Well that depends on the types and quantities of strawberries that they are eating. Our research aims to identify the best varieties and quantities to consume, so that we can advise people on how to maximise the health benefits offered by strawberries.