One size doesn't fit all for functional foods, say scientists

The marketing and testing of functional ingredients will become much more sophisticated in future to take account of genetic variability between consumers, according to experts in the relationship between diet and genes.

A growing number of clinical studies revealed that genetic variations between volunteers were responsible for significant differences in their responses to omega-3s, carotenoids, glucosinolates in veg like broccoli, vitamins and minerals, delegates at a Leatherhead Food International conference on nutrigenomics were told.

If you gave 100 people a high dose of cholesterol-busting long chain omega-3 fatty acids, up to a quarter would actually see an increase in 'bad' LDL (low-density lipoprotein) cholesterol, said Dr Anne-Marie Minihane from the human nutrition unit at the University of Reading.

This is because about 20-25% of the population has the 'E4' variant of a gene associated with fat metabolism called ApoE, she said. "High dosage supplementation of DHA (docosahexaenoic acid) will probably have a deleterious effect on a quarter of the population."

As drug companies have known for years, a certain percentage of consumers buying foods or drugs will always be wasting their money because their genetic make-up meant that they were less responsive to, or even detrimentally affected by, the active ingredients in question, said Minihane. "Large food manufacturers are increasingly sensitive to this and in fact two major food companies we are working with on clinical trials at the moment are recruiting prospectively by genotype."

A one-size-fits-all approach to nutrition was no longer appropriate, she added. "We know, for example, that people with a particular genotype of the eNOS gene (which codes for a protein controlling the elasticity of blood vessels) have higher risk of cardiovascular disease. More targeted nutritional interventions for these people will be required."

By 2020, genetic testing to help individuals identify whether they were more likely to develop health problems would be commonplace and personalised therapies and dietary advice would become more widely available, she said.

About 99.8% of our DNA was identical to that of the person sitting next to us, but it was becoming increasingly clear that the 0.2% difference was a key factor explaining why two people exposed to the same environmental factors were not equally susceptible to chronic disease, she said.

"People with the ApoE4 variant should avoid a diet high in saturated fat, because it will send their cholesterol through the roof. They are also far more susceptible to developing Alzheimer's. Unfortunately, we don't know the extent to which this risk is modifiable through nutritional interventions."