Tuesday, November 14, 2006

At Least You'll Get Enough Zinc

Zinc is a micro nutrient, as are all vitamins and minerals that are essential in minute amounts for healthy cellular growth and metabolism.

There's actually a micronutrient encyclopedia that details how much of them we need (called Dietary Reference Intakes or DRIs) printed by the Institute of Medicine (IOM). The IOM describes their work on DRIs as, "eight exhaustive volumes" (there's a great sales pitch) but if you'd like some lighter reading you can pick up their 560 page summary for the low-low price of just $44.96.

As noted in yesterday's post, Canada's Food Guide has been explicitly modeled to ensure that Canadians who follow the Food Guide will meet their daily micro nutrient requirements.

You might think that sounds like a good idea. Certainly having a vitamin or mineral deficiency can lead people to medical illness.

I guess the question is what's more important, steering people to dietary choices that prevent micro nutrient deficiencies, or steering people to dietary choices that minimize the risk of chronic diseases?

The answer's a no-brainer.

The fact is there isn't a rash of micro nutrient deficiencies in Canada, and that's despite the fact that the majority of the population does not currently practice tremendously healthy eating. Even back in 1982 when the then Food Guide recommended the consumption of far less food (the 1982 Food Guide recommended that we consume 113% fewer grain products, 50% fewer milk products, 67% fewer vegetables and fruit and 25% fewer meat and meat alternatives) there were no micro nutrient deficiency outbreaks.

The fact is, the bulk of our understanding of the role of diet on the prevention of chronic disease has to do with the effects of increased or decreased consumption of whole foods, not of micro nutrients.

The fact is the burden of chronic disease in our society is climbing at an atrociously rapid rate (the WHO projects a doubling of cases of type 2 diabetes by 2025).

The World Health Organization in their 160 page Technical Report Series #916, Diet, Nutrition and the Prevention of Chronic Diseases summarized the evidence for and against both nutrients and foods in the prevention of chronic disease.

To quote the report with regards to targeting nutrients,

"Seldom is there a single "best value" for such a goal. Instead, consistent with the concept of a safe range of population averages that would be consistent with the maintenance of health .... Sometimes there is no lower limit, this implies that there is no evidence that the nutrient is required in the diet and hence low intake should not give rise to concern."
On the other hand, with regards to whole foods, Technical Report #916 has a lot to say, as does reams of research into the effects of foods and their role in chronic disease prevention.

To be consistent with our best evidence the WHO, and anyone who's up to date with the medical literature, would say that if our Food Guide reflected best available evidence it would be unambiguously encouraging Canadians to preferentialy consume (in no particular order):

  • Fruits
  • Vegetables
  • Whole grains
  • Legumes
  • Fish
  • Nuts

  • While minimizing the consumption of:

  • Free sugars (white rice, white flour, white sugar, potatoes)
  • Red meat, and more specifically processed red meat
  • Salt
  • Hydrogenated oils

  • I'm sure that the majority of you reading this blog already know the above lists to be true.

    Why then does the proposed Food Guide not make these explicit recommendations?

    Truly, I don't have the answer, but however you slice it, the answer is disturbing.

    Bottom line, in a country where there are no outbreaks of micro nutrient deficiencies; in a country with a tremendous burden of chronic complex diseases; with a Food Guide where the units of guidance are foods and not micro nutrients; with a backdrop of research where the wealth of our understanding lies again in foods and not nutrients; to have relied on micro nutrients to shape the recommendations rather than foods is at best short sighted and at worst, a dearly missed opportunity for change.

    Tomorrow: Consultation? What Consultation - I suppose if by consultation you mean what fonts you like, then yes, there was an extensive consultative process

    Yesterday: Broken from the Get Go - Get this, the new Food Guide is based off of current Canadian dietary patterns....where 40% of all vegetables consumed are potatoes with over half of the potatoes being consumed coming from french fries or potato chips. That seems smart.

    (To see the WHO summary on whole foods and chronic disease in more detail and a mirroring of the concerns of this post by the Centre for Science in the Public Interest (CSPI) please read CSPI's December 2004 formal submission to Health Canada on their then concerns on the revisions to the Canada Food Guide. Unfortunately since that time, their concerns haven't changed)