HOW TO PREVENT CANCERS

CNiC recently gave a big endorsement of Mark Bittman’s new Food Matters cookbook. This week, we gave two of the recipes a whirl.

One of the things that appeals to me about Bittman as a food writer is that he appreciates fine complex cuisine, but pushes us to realize that every meal (or most meals) need not be complicated (in preparation or flavor) to be delicious.

Food Matters has a recipe for simply making grains. Bittman points out that there are lots of wonderful whole grains in the market (or your pantry) and you can often make substitutions. In an effort to clean out some of what is in our pantry and freezer in anticipation of the holiday cooking madness that will shortly begin, I decided to use up the barley we had following Bittman’s recipe. Cooking barley is as simple as cooking rice and Bittman’s recipe nicely points out the variations in cooking times for different grains, including different types of barley, along with tips for knowing how the grains are done. The directions were clear and the result was perfectly cooked barley.
The grain cooking instructions are followed with a nice list of suggested variations – essentially things you can add to the grains. Looking at the list, I realized our refrigerator contained two of the suggestions – tomato sauce and leftover meat, in my case, some left over roasted chicken from Sunday dinner. I tossed a couple tablespoons of marinara sauce
with some chopped chicken
and the barley and called it dinner. Served with a heaping portion of sautéed zucchini, it was a simple, but tasty meal and everyone seemed satisfied.
Cooked barley reheats nicely so I actually cooked that in the morning while we were getting ready for school/work and put it in the fridge. When I got home from work, I added the other ingredients and reheated.
It meant dinner got on the table in 5 minutes (which was basically the time it took to sauté the zucchini). Pretty great for a weeknight.

Later in the week, I gave his recipe for vegetable fried noodles a whirl. Plenty of food writers and chefs have pointed out that stir fry is a great way to get dinner on the table fast, but our house has never embraced this for some reason. I expect that will change. Again, Bittman’s recipe is designed as a template – with plenty of suggestions for variations. We went with the recipe as written – cook some soba noodles, toss with a little sesame oil. Sautee julienned carrots, sliced celery, chopped scallions and some snow peas with a bit of garlic and ginger in a smidge of oil.
Toss with a little stock or water (I had some homemade chicken stock on hand that I made from Sunday’s roasted chicken carcass).
At the end, toss with a bit of soy sauce and an egg. Toss all that with the cooked noodles and top with a few chopped peanuts.
Unlike fast food/take out fried rice or noodles – this wasn’t overly sauced. I could taste the vegetables – which was great because they were obviously where most of the money in the meal went – and because I bought some great fresh ones, it tasted great. Limiting the soy sauce also limited the salt content in the meal. This one was a big hit all around – and because the noodles are mixed with the vegetables at the very end, I simply separated out a bit of each before serving to my toddler, who is at that stage where different foods should not touch on the plate.

Food Matters isn’t a vegetarian cookbook, but it is about making meat (red or other color) an accent and not the centerpiece of your meals. Both meals included some chicken (one had a few chunks of chicken, the other used chicken stock because it was what I had and an egg, which was optional), but could have very easily been made vegetarian.

Food Matters reminds us that eating healthy food can be both simple and tasty.

One of the key foundations of epidemiology is causation (Hill’s causal criteria were first detailed in 1965) – and that conclusions about causation are based on a number of factors including a plausible biologic mechanism. Thus, research papers outlining associations between risk factors and disease typically outline the likely or possible mechanisms that would link the risk factor with the disease endpoint. Despite convincing evidence from observational studies that link numerous risk factors with cancer endpoints, in most cases we can’t point to a mechanistic pathway and say “this is how.” In part, this is likely because many risk factors operate through multiple pathways. But understanding those pathways remains an important priority in cancer prevention research.

While a sufficient body of evidence exists that numerous independent bodies have concluded that physical activity is causally related to a reduced risk of several cancers, including colon and breast, the mechanisms remain relatively poorly understood. A few candidates are typically mentioned and are the focus of most current research in this area – physical activity has anti-inflammatory effects, reduces insulin resistance and may alter sex hormone levels.

Mechanism studies tend to be conducted in animals or cell lines and if conducted in humans, tend to be relatively small or from non-randomized trials. This week, results came from one of the largest supervised exercise training randomized controlled trial studies conducted in women. 316 women between 18 and 30 were enrolled in a 16 week aerobic exercise intervention. The women randomized to the intervention arm participated in physical activity at levels recommended by public health guidelines: at least 30 minutes of activity at least 5 times a week. Adherence and retention rates were both high indicating a methodologically rigorous study.

Overall, the study found little that could be a link in the causal pathway between activity level and cancer.  The insulin-like growth factor (IGF) family of hormones and binding proteins, which are involved in growth and development, have long been suspected as possible mediators between exercise and cancer.  Yet, apart from a statistically significant lower level of IGFBP-3 in controls, none of the other IGF levels were different between exercisers and non-exercisers.  The same held for levels of glucose, insulin, and a measure of insulin resistence (HOMA). 

What does this mean? Previous studies have suggested that the IGF family is associated with premenopausal breast cancer risk – specifically that IGF-1 levels are associated with increased risk of ER+ breast cancer. It may be that the physical activity levels recommended by public health guidelines aren’t intense enough to materially alter levels in the IGF family. Or it may be that exercise needs to be consistent over a longer period of time to see significant changes.

Does this mean we should dismiss the data showing that exercise reduces cancer risk? Not at all. What it does highlight is that randomized trials have great utility for examining very precise questions. This trial studied one specific dose of exercise over a specific number of weeks. The trial can’t tell us what more vigorous activity would have done, or what 60 minutes/day of activity does to the IGF family or what consistent activity over several years does, if anything, to IGF.

Sometimes, randomized trials raise more questions than they answer. Thus, to move science forward, we need BOTH observational and randomized trial evidence.