- Print Friendly - Help

Food Focus May 2008

Exposure to food can change your life

Our bodies are complex mechanisms that need food to survive, but such food may have more far-reaching consequences than we realise, as Professor Shaw explains

By disproportionately focusing on food risks we are missing the importance of the incredibly complex interactions between food and our biochemistry – in fact we are only just now beginning to get an inkling of what is going on.

Life is a risky business and food is just one of the many risks we dodge every day. Despite this, most of us live well into our 70s and a car accident is more likely to lead to our premature end than food. In fact food risks don’t have a great impact on longevity at the broader population level.

Our exposure to food begins in utero where we live in a highly regulated foodsafe environment – NZFSA might well aspire to this level of effective food safety regulation! The placenta ensures that only safe molecules can access the foetus – with perhaps some low-level baddies to enable the developing child to be born with a biochemical awareness to prepare it for everyday toxins later in life.

We have evolved complex metabolic systems (cytochrome P₄₅₀ mixed-function oxidases and conjugation systems) to detoxify and facilitate excretion of ingested toxins; this is why we can survive after eating food which contains a myriad natural toxic chemicals. These systems are designed to adapt to different toxic chemicals’ molecular structures. They make short work of most pesticide and veterinary residues, even though these chemicals were not around when the systems evolved millions of years ago.

As we begin to better understand our interaction with food it is becoming increasingly clear that a simple chemical approach is far too naive to explain the effects food can have. It is known that genes are regulated by components of food and if this occurs in utero the effects might remain for the child’s entire life. For example, pregnant rats fed high-fat diets produce pups that become obese as they grow up, even if the pups do not get a high-fat diet themselves. A similar situation might occur in Pacifika families, where obesity seems not to be entirely diet-related. We have a great deal more to learn about this – suffice to say that in utero exposure is likely to shape our metabolic lives.

Some dirt may be healthy

There is no doubt that the simple metabolic approach to considering both the good and bad effects of food is not the entire story. Rather, at one level there is a complex interaction between toxic components of food and the body’s detoxification system (which itself is up-regulated on demand), and at a higher level there is an even more complex gene-regulatory interaction between food components and the cell’s nuclear apparatus. This can have either a direct effect on the individual (eg, broccoli down-regulates colon cancer genes) or an indirect effect via the maternal system. For example, maternal exposure to allergens might explain the increased incidence of peanut and other allergies in children. On the other hand, a too-clean environment reduces maternal and peri natal exposure to fragments of bacterial cell walls or viral coats that might pre-arm the child immunologically against exposure to foodborne microbes for an entire lifetime.

Pregnant women and youngsters have a penchant for eating peculiar things – apparently I ate coal as a child! Perhaps this ensures that the offspring are metabolically and immunologically prepared for later life. We must be careful we don’t make our world too clean and therefore not allow our biochemistry to adapt and develop to combat its future insults. This is just the beginning of the realisation that food components are likely to have effects on our development and wellbeing that would have been regarded as science fiction a decade ago.

Professor Ian Shaw is Pro-Vice-Chancellor (Science) at the University of Canterbury, a member of the NZFSA Academy and an Associate Investigator in the National Centre for Research in Growth and Development at the University of Auckland.

Each issue our columnist gets to air their personal views on a subject close to them. These views do not necessarily represent those of the New Zealand Food Safety Authority, but are published here to encourage debate on issues of current interest.