HOW TO PREVENT CANCERS

We've dedicated a number of posts over the past year on the policy and health pitfalls of indoor tanning - from the potential benefits of the "tanning tax" (post) to surprisingly high rates of tanning by some youth (post).  Now comes a fascinating, if not perfectly surprising, little analysis on the influence parents can have as indoor tanning enablers.

The small study - reported in the New York Times (story) and printed as a research letter in the Archives of Dermatology (letter - subscription required for full text) - included just over 200 female college students who had at any time in their lives tanned indoors.  Results showed that 40 percent of these students had had their very first tanning experience with their mothers, and that this mother/daughter group of students started tanning at earlier ages and were much more likely to be heavy tanners in college than those who'd first tanned with friends or gone on their own.

For an activity that has well demonstrated health risks, it's surprising that such a high percentage of students were actively introduced to tanning by a parent.  Using an extreme example, it's hard to imagine such a high percentage being introduced to smoking in the same way.

But perhaps the most interesting aspect of the study is how well it demonstrates the dual way that family history may influence future risk of disease.  Genes can certainly play a role but so to can the lifestyle choices that also permeate families - whether it's the food served in the kitchen or the activities done for leisure.  And with over half of all cancer and up to 75 percent of heart disease and diabetes preventable with things we can all do, it's important to realize that the choices made by families could have just as much, if not more, influence on health than the genes they carry.

While lifestyle contributes substantially more to risk of cancer (and other chronic diseases) than genetics alone, the interplay between genetics and lifestyle is a subject of increasing interest. That's what makes a new study out of the UK, published in PLoS Medicine so exciting.

The researchers took 12 genetic mutations that had previously been found to be associated with obesity risk and examined how they combined to be associated with risk of weight gain. The presence of each additional mutation increased risk of weight gain -- the more mutations, the greater the risk. The mutations significantly increased the risk of obesity by 16%. The researchers then did something quite novel, using the data the participants reported about how physically active (or not) they were, the researchers re-examined the associations. In the inactive men and women, the association was stronger than in the inactive people. What this means is that the effect of genes were stronger in the people who were inactive - or - that physical activity "erased" some of the genetic predisposition - about 40% of it.

What does this mean for those of us who have no idea how "genetically predisposed" we might be to obesity? Physical activity has benefits for everyone, but for individuals who are genetically predisposed to obesity, physical activity is especially important. It also means that a genetic predisposition to obesity isn't cause for "doom and gloom" - there ARE things you can do to counter it - notably, being physically active!