Milking your diet for all it's worth

As some who read this blog might know, I used to be employed by the Dairy Farmers of Canada as their Director of Nutrition. Because of that role I was a bit reluctant to write specifically about dairy products, concerned that some might view me as biased towards them. That’s possibly true, but my job required me to read all of the research (both positive and negative) about dairy and that led me to be especially knowledgeable about their role in diet. My point here, and I do have one, is that it’s a disservice to readers to ignore this food group because of a potential misunderstanding about my motives. This blog, therefore, will cover the latest research on dairy, particularly as it relates to the report on “Food, Nutrition, Physical Activity, and the Prevention of Cancer” from the American Institute of Cancer Research and the World Cancer Research Fund (AICR/WCRF)


Colon Cancer

The evidence is very persuasive and the distinguished AICR/WCRF Expert Panel concluded that higher milk and calcium intakes may help reduce the risk of colon cancer. On average, Canadian adults consume only half of the recommended two servings per day…and my personal belief (based on the research I’ve seen) is that they should be having at least three servings. The bottom line (no pun intended) is that if you care about your colon you should make sure that milk or milk products are part of each meal. The big guns in the nutrition game suspect that it’s the calcium in dairy that is so important in colon cancer prevention, but other possible players are vitamin D, sphingolipids and conjugated linoleic acid (CLA). While it’s certainly possible that calcium from any source (say, sardines or kale) would be just as effective, they don’t contain those other factors, not to mention the fact that even sardines and kale lovers don’t eat those foods three times a day.

Breast Cancer

The main message from the report is that obesity is a major contributor to cancer risk, especially breast cancer. The report therefore emphasizes the importance of maintaining a healthy weight. There is an impressive amount of research indicating that women who have consumed three servings of dairy since childhood have two things going for them breast-wise: 1) they’re more likely to keep their weight in check, and 2) they have a lower risk of breast cancer. I’ve occasionally heard the comment that Japanese women have a low risk of breast cancer and they don’t drink milk .In the first place, Japanese are the highest per capita consumers of yogurt in the world, and secondly, although the risk of breast cancer is low, there is research showing that women dairy consumers have an even lower risk than their non-dairy consuming counterparts. Genetics most likely has a part to play as well. Vitamin D comes to the fore again, as evidence continues to mount that women with a greater exposure to this vitamin (either from sunlight, diet or supplements) are at reduced risk for breast cancer. Most experts agree that daily intake of the “sunshine” vitamin should be at least 1000 I Us (International Units). If you’re going to take a supplement (and I think you should) then make sure that the supplement doesn’t also contain vitamin A, since too much of that vitamin is not so kind to your bones.

Other Cancers

Perhaps the most controversial of cancers as related to dairy consumption is cancer of the prostate. There are over 70 published studies that address this topic and overall the data indicate no association between consuming the recommended levels of dairy foods and increased prostate cancer risk. To date, only one randomized clinical trial has been conducted on the effect of calcium intake on prostate cancer, and it showed no effect of calcium on prostate cancer risk. In fact, this study showed a slight non-significant decrease in risk with calcium supplementation. At the risk of sounding like a broken record, I must point out that vitamin D supplementation is thought by many to be protective.
Both ovarian and kidney cancer were found to have no association with dairy consumption but, interestingly enough, there is a fair amount of evidence that milk consumers have a lower risk of bladder cancer.
In summary then, the best advice in terms of reducing g your risk of cancer would be to follow a healthy diet based on Canada’s Food Guide, be active, maintain a healthy weight…and, my personal recommendation: take a vitamin D supplement.