December 2015 | Issue 21

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Food for thought

By Nicole Lim
Assistant Director, Communications & External Relations

Barbeques are bad for you, but coffee (up to four cups a day) and champagne (three glasses per week) are good, is how the latest global health guidelines could be summed up. But how prescriptively should these guidelines be applied to an individual?

According to LKCMedicine Professor of Metabolic Medicine Walter Wahli, global guidelines provide useful recommendations for the average person, but who fits this profile is becoming more complex. As we understand more how food affects gene activity (which in turn controls everything from how we process and store nutrients to how we use them), we are building individual profiles, which show that we respond differently to food based on factors including ethnicity, family history, age and gender.

Prof Wahli, who first became interested in the interplay between nutrition and genes back in the early 1990s before it was the hot topic it is today, was among the first to discover that the molecules that bind to and activate the then-newly identified peroxisome proliferator-activated receptors are found not just within the body, but also in food, such as Omega-3 fatty acids. This showed for the first time that diet could directly influence gene expression. Prof Wahli said, “This was in the 90s and was really a very revolutionary concept. It was very difficult to establish in the scientific community that what you eat can directly bind to proteins that control gene expression.”

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Professor of Metabolic Medicine Walter Wahli focuses on the role of nutrition on health

Since then, the field has blossomed and a complex picture of the intricate relationship between food and health is fast emerging. By far the best characterised relationship is the rise in rates of overweight and obesity (current rates say one in six people is obese or overweight), which is largely attributable to the unhealthy phenotype that emerged from high-density energy food and lack of physical activity. But it is not just metabolic and cardiovascular diseases that are triggered by our diet.

“We know now that about 30 per cent of cancers are associated with food, so there is a clear relationship between what and how much we eat and how healthy we are,” said Prof Wahli, whose current work includes projects on how the body prepares itself for the transition from in utero nutrition high in glucose to the high fat diet from breastmilk after birth, as well as how diet and the microbes living in our gut, the so-called microbiome, contribute to the development of fatty liver disease.

Through nutrigenetics, scientists have been making headway in identifying how our genes respond to individual food ingredients. For example, people with low levels of the enzyme CYP1A2 cannot metabolise caffeine well, so drinking four cups of coffee would lead to an increased risk of heart attack in this group of people.

But while we know that some substances are bad for some people, more often than not, the health impact comes from more than one source. Since the turn of the century, scientists have been studying the other side of the coin, using ‘omics’ technologies to investigate the impact of our diet in its entirety on the expression of our whole genome. Only last month, a study developed a personalised response algorithm that predicts an individual’s glycaemic response based on personal, clinical, gut microbiome, dietary and lifestyle information. It found that responses varied much more than expected, with even the generally considered healthy tomato causing significant blood sugar spikes in one participant.

“This work is a proof-of-principle of the benefit of customising nutrition to each single individual,” said Prof Wahli, who believes that the day when your nutritional profile becomes standard health information is not so far off.

While such personalised support plans may be closer to reality than science-fiction, nutrition does not just perform a functional purpose in our lives. It also plays a key social role and is a source of enjoyment for many. To come to a healthy compromise between eating what’s good for you and enjoying your meals, Prof Wahli believes that we need to change our approach to food. “We need to ‘care’ about what we eat. We have to see food as more than just a way to fill our stomachs, but as a way to maintain or improve our health. In school, children learn to read, write and calculate as well as about the benefits of physical exercise. We should also teach nutrition to change our relationship and attitude with food.”

A comment that is never more apposite than during festive seasons. So while it is likely to lead to more ounces on the weighing scales, a rich Christmas dinner is unlikely to lead to any long-term health damage. “I would advise moderation and diversity when eating. But when it comes to the occasional festive indulgence, there is unlikely to be any long-term damage,” said Prof Wahli.