Cass Avery: Of mice and menus and a constant diet of advice

I'm entering a state of food fact fatigue. In the past week we've been hit with a barrage of new facts, recanted findings and extraordinary work in progress.

The Swedish scientists that scared us last year when they found high levels of a carcinogen called acrylamide in cooked potatoes have made another appearance to reveal it is safe to go back to the chip aisle because the levels of nasty carcinogens aren't high enough, it turns out, to be harmful to humans.

In the same week a different group of European scientists are telling us that we shouldn't have been eating farmed salmon because canthaxanthin, an additive used to enhance colours in salmon, egg yolks and poultry, can cause eyesight problems.

And to really take the cake, last week we discovered unbelievably thin mice hogging out on their pellets with no repercussions. They're called "Firko" mice and they can eat as much as they like and not gain weight thanks to their fat-specific insulin receptor knockout which means their fat cells can't respond to insulin and fat cells need insulin to store fat.

Weeks like this in the food world are symptomatic of the bombardment of messages we get about what we can and can't eat. Some instructions get retracted, others get modified, some turn out to be hoaxes and there's an endless supply of theories and warnings.

Have you heard the one about pepper? Black pepper has been reported to congest blood vessels so people with haemorrhoids and varicose veins are being warned off.

Even the barbecue has come in for some scientific carcinogenic flack. The American Institute for Cancer Research says grilling causes meat, fish and poultry to produce cancer compounds.

Another cancer-causing substance forms when fat drips onto the barbie and is carried by the smoke and flames onto the food above.

The eight-glasses-of-water-a-day truism is in question and I've been warned by a nutritionist not to take it too literally because too much water flushes out vitamins and minerals.

Even orange juice - the longest standing ally in the quest for a modicum of good health because of its vitamin C - is suddenly being scientifically maligned. It turns out vitamin C binds to free radicals in the air and disintegrates so orange juice is high in vitamin C only if it's very fresh. This is just getting ridiculous.

Food fact fatigue has well and truly set in on the old food news, such as sugar being destined to be the bad guy for all eternity in the research - Americans eat almost their own body weight in sugar every year. We love Coke but there's about eight teaspoons of sugar in every can. People who used to worry about sugar read about carbohydrates and swapped fears.

Carbohydrates were to the 1980s what fat became to the 90s. But when you consider the success of high-fat fast foods (according to the Washington Post online fast food calorie counter, a McDonald's large fries alone contains almost a quarter of our daily calorie needs and a third of our daily fat quota) the fat message seems to be fatigued as well.

So as the century rolled over, high protein turned up as the next slimmer's answer. And in the news last week - a New Zealand team announced they will research these high-protein diets. We'll wait with carbohydrate-starved enthusiasm for the scientific truth about that one.

Then there are moral food fear facts - Dole, Chiquita, Monsanto and Nestle have all been charged with producing nutritional, but not morally viable, foods.

There's the issue of child slave labour used to pick cocoa beans making chocolate consumption an evil against social responsibility in the global community.

And the chocolate guilt is on the rise just when science has discovered how we could eat endless amounts of it without having to deal with the expansive consequences. It's those Firko mice who, after a change in a single gene, have been gifted with the ability to eat as much as they want while staying thin.

It sounds like a dream scenario but all I can see in my mind is queues at fast food outlets that run for blocks, confectionery firms becoming the new start-ups and gyms with tumbleweeds bundling across the aerobics floor.

While science is constantly rolling out food news, fiddling with every molecule of the relationship between what we are and what we eat, the allusion is maintained that what happens to lab mice will possibly one day happen to us. They are warm and fuzzy crystal balls that foretell our biological future.

But what the fortune-telling mice can't reveal with their extraordinary physiology is how their medical miracles will translate in emotional and social terms once their biological bounty is released from the lab.

The possibility of unlimited consumption is psychologically horrifying and the constant shifts in received wisdom about the safety of what we consume adds a tragic level of farce to the excitement generated by the warm and fuzzy Firkos.

Herald feature: Health