Can super-food fix bad genes?

Imagine going to a doctor with severe arthritis and instead of being prescribed a drug you are told to eat a special kiwifruit grown only in New Zealand.

It's not impossible. Food that may be able to help mend the health problems caused by our genetic makeup is being explored by a team of New Zealand scientists.

The research hopes to take what we now know as functional food - food that is linked to disease prevention, such as broccoli to colon cancer - and connect it directly with the gene map of an individual or group of people.

The idea is to find the gene "switch" that makes people susceptible to a disease and discover the food - or a potent nutrient in the food - that turns the switch off. The potential benefit for New Zealand is that if our scientists can intensify the active ingredient through selective breeding they can claim the exclusive plant variety rights.

Other countries are also involved in research and eventually it is hoped this science - nutrigenomics - will be refined to apply to the treatment of all illnesses that have a genetic base.

At present, this is still a long way away. It is believed that 10 million genetic differences between individuals exist and so far only around 20 are understood.

The potent food ingredients are micronutrients, dietary compounds such as vitamins and minerals that are required in small amounts in the diet, or macronutrients, organic compounds, like proteins, amino acids, carbohydrates and lipids, which are needed in large amounts.

Professor Bruce Ames, of the University of California, Berkeley, argues that micronutrient deficiencies are widespread and may be a key preventable cause of the diseases of ageing.

His theory is that the degenerative diseases which accompany ageing, such as immune dysfunction, cancer, dementia and stroke, might be delayed by the inexpensive intervention of micronutrients.

In Australia, research into micronutrient deficiencies that damage dna has led to a simple diagnostic blood test to discover damage to a type of white blood cell and to the micronutrients that can reduce it.

At Tufts University, Massachusetts, Jim Joseph is investigating "berrying" the aged brain. His findings suggest that berries may improve learning and memory and protect against Alzheimer's, Parkinson's, heart disease, vascular dementia, cancer and arthritis.

IN New Zealand, scientists are working on gut health. A 50-strong group from the government science institutes AgResearch, HortResearch and Crop & Food Research and Auckland University is spending $3.2 million a year. Known as Nutrigenomics New Zealand, the group is four years into an initial six-year funded term and expects to need another six years.

It is slow work.

The leader, Professor Lynn Ferguson, who heads the university's nutrition department, says "we've reached a point on how to study it". "We understand some of the science we didn't understand when we started out."

The group's focus is on Crohn's disease, where foods are known to play a role in triggering the genes that cause this inflammatory bowel disease. Some overlap with genes associated with asthma and arthritis has also been found.

The scientists are looking for two things, the gene "switch" that make people susceptible to inflammation and a nutrient that turns it off.

About 1000 Crohn's patients are taking part and have begun by listing the foods they can and cannot tolerate. Energy and carbonated drinks, hot curries, salami, grapefruit, cream, fruits with small seeds, alcohol, coffee and corn are bad. Bananas, ginger, starchy vegetables and couscous are good.

Cabbage has sprung a surprise. Crohn's people with a certain gene find they can't eat it but other patients without the gene find it beneficial.

Findings of a low level of selenium in the blood serum of Crohn's patients were to be expected. Selenium and folate are two nutrients that are naturally low in the New Zealand diet.

Selenium is found in wheat-based cereals imported from Australia and Brazil nuts and deficiencies have been associated with prostate cancer. A diet lacking in folate, which is in green-leafed vegetables, has been linked to a risk of cardiovascular disease.

Professor Ferguson says the science so far is showing that the well-known food pyramid of dietary priorities may be too simplistic. "Recommendations may need to be fine-tuned, particularly for people who have a susceptibility to a disease or who are just not in optimal health."

An example is the 20 per cent of the population who need twice as much folate. "It's not going to be a life or death situation for them but it will enhance their health, performance and general state of well-being."

Another is the people whose genes produce a bad reaction to too much of the polyunsaturated acids in oily fish that are generally considered beneficial.

Ultimately, mapping a person's unique genetic makeup will mean any one person's dietary requirements can be far more finely tuned, she says. "It could also mean that not only would someone know which foods to avoid, but they could also learn what foods are good for them and should be included in their regular diet."

In the meantime, the Crohn's patients are first in line. She says a clear picture is still to emerge, but it appears the genes involved are in clusters, not scattered across the genome, which helps to simplify treatment. "It looks like some of the dietary advice will depend on which of those groups of genes is affected."

It is expected this work will lead on to other inflammatory illnesses and other nutrients that turn off harmful gene "switches".

HortResearch biochemist William Laing's job is to find foods high in the key nutrients. Asked what foods he has been looking at, he replies: "Everything and anything we can think of."

This includes a wide variety of fruit and vegetables as well as milk products, green tea, red wine and chocolate. HortResearch's wide germplasm base of kiwifruit and apples is a rich source.

"The idea is to obtain value for New Zealand. It's pretty hard to protect a food component in terms of intellectual property, but one way is to breed a fruit or a vegetable that is naturally high in the active ingredient and then you can protect it through plant variety rights."

AgResearch scientist Warren McNabb, who leads a team that tests promising nutrients on rats and mice, says the science is still little understood. "Knowledge is rapidly growing, but we're only scratching the surface."

As more genes are found to be nutrient-sensitive it gives hope that treatment will be of broad population groups, based on ethnicity or a tendency to heart disease or cancers, rather than individuals, he says.

This might be a way around issues of personal security that arise over having people's genomes stored in a database somewhere. It is a question exercising scientists, he says.

"In Singapore, where they are seeing an increase in western diseases as their diet changes, all babies are genotyped. But in other countries that is a privacy issue."

Progress might be slow, but he says it is essential that New Zealand actively participates in the science.

"What's happening is a transformational change about how we're going to be talking about foods in the future and New Zealand, a food export-driven country, can't be left out. Farmers have to be aware of this. They can't be pumping out that same old stuff all the time."

 

- © Fairfax NZ News