Sunday, November 12, 2006

Broken from the Get Go

So let's say you've decided that Canadians aren't making the healthiest of dietary choices. Let's even say you're Diane Gorman the then Assistant Deputy Minister of the Health Products and Food Branch of Health Canada and you're kicking off the process of revising the Food Guide. You'll be quoted as saying,

"The current edition of the Guide is 10 years old. Within this time, scientific knowledge about the relationship between diet and health has evolved. The lifestyle of Canadians has changed and the environment within which people are making choices about healthy eating has changed significantly."
Suggesting of course that the Food Guide's going to have to help Canadians make healthier choices in our evolving and toxic food environment.

Do you think that a good starting point for improving the choices Canadians make would be to collect data on what Canadians are currently consuming?

I suppose it might be nice to have that information to contrast it with what you're going to be recommending.

Do you think that using that information to ensure that you make as few changes as possible would be a good idea?

Health Canada does.

In an overly complicated document, Health Canada detailed their methodology on how they came up with the skeleton for our next food guide.

To summarize as best I can,
  1. A pool of "food choices" was created using provincial food and nutrition telephone survey data from British Columbia, Manitoba, Ontario and Quebec.

  2. The popularity of what was most commonly being consumed in those provinces was given a rank. In a moment of clarity in the document Health Canada explains,
    "For instance, if the relative popularity of apples is 30% within the available fruit choices, then there is a 30% probability that apples will be included as any given fruit choice."
  3. 500 "Test" diets were created using the ranked popularity of foods for every age and sex group detailed by the proposed Food Guide.

  4. The test diets were evaluated to see if following them would lead Canadians to meet their nutrient requirements (a whole post will be devoted to why this isn't a great plan tomorrow). Here's Health Canada's quote on the matter,
    "The test diets are evaluated to see if nutrient requirements are met. The modeling switches back and forth until no further adjustments to the diet pattern are needed to achieve nutrient targets."
  5. Presto-NO-chango we've got new recommendations that stick as closely as possible to what Canadians are currently eating.
It seems quite backwards to me that the basis for our new Food Guide should be our current pattern of eating.

The Food Guide should be steering Canadians to healthier foods as a whole. By starting from our current dietary baseline rather than from scratch, Health Canada immediately abandoned the option of simply using the best available medical evidence to recommend diets that minimize the risk of chronic disease development.

There are many examples of how this modeling can go wrong because the simple fact that Canadians eat a lot of red meat, potatoes and refined grains don't make them healthy choices.

To illustrate what I mean, let's take a closer look at a food too rarely singled out - potatoes.

Over 40% of the vegetables consumed by Canadians are potatoes, and of that 40%, over half are in french fry or potato chip form. Therefore according to Health Canada's formulas, in their test diets there is a 40% probability of potatoes being included as a vegetable choice. There are indeed nutrients in potatoes, but the question that's more important to ask is, "Is there any risk in eating a lot of potatoes"?

The answer is certainly yes.

It's a certainty firstly because half of the potatoes consumed by Canadians are fried.

It's a certainty secondly because ample evidence exists to suggest that high potato consumption has risk. Potatoes increase blood sugar and insulin levels nearly as fast as pure white table sugar which is potentially why in a 20 year study looking at 84,555 women there was an increased risk of type II diabetes in women with higher potato consumption.

Dr. Walter Willett, the chair of nutrition at Harvard since 1991 and arguably the most important nutritional epidemiologist in history has this to say about potatoes in his exceptional book, Eat, Drink and be Healthy,
"More than two hundred studies have shown that people who eat plenty of fruits and vegetables decrease their chances of having heart attacks or strokes, of developing a variety of cancers or of suffering from constipation or other digestive problems. The same body of evidence shows that potatoes don't contribute to this benefit. Potatoes should be an occasional food, eaten in modest amounts, not a daily vegetable."
Without a doubt, the Food Guide's take on potatoes should be to recommend their minimization in your diet. Guess what? It doesn't.

By modeling off our current dietary choices, healthier food recommendations will be ignored simply because current Canadian eating patterns meet the dietary reference intake patterns for micronutrients.

Problem is, our current level of understanding of the effects of diet and chronic disease prevention is much more about the foods we eat rather than the nutrients we consume, which is why it would be worth recommending that we minimize foods such as potatoes rather than simply rate them by micronutrient content and worse still, popularity.

Tomorrow: At Least You'll Get Enough Zinc - Health Canada cares a lot about nutrients...not so much about foods. Last time I checked, I eat foods, not nutrients.

Big Food Has a Seat - Health Canada's bizarre inclusion of the Food Industry in the shaping of the Guide.