(Crossposted from Depressed Metabolism)

Consumers are constantly bombarded with advice about health. Lower your cholesterol, avoid carbs, take dietary supplements, avoid Teflon, get a full body scan, etc. Such advice does not fall on deaf ears. Who does not want to remain healthy, look good, and extend life? Two other factors contribute to our eagerness to consume and follow health advice. First, the accelerating growth of knowledge in fields such as biology and biochemistry. Second, a reasonable assumption that if some chemicals and behaviors can harm us,  there must be chemicals and changes in behavior that can confer great benefits.

The role science plays in contemporary thinking about health is a double edged sword. On the one hand, it can be used to debunk grandiose claims about health by subjecting these claims to rigorous scientific investigation. On the other hand, the authority of  scientists can can be abused to support products or lifestyle changes for which there is little evidence. For many people and journalists, the phrase that “research proves” something is often enough to act on health recommendations, regardless of the nature and quality of the evidence. But it does make a lot of difference whether “research proves” means a small number of experiments in a test tube or a multi-country randomized human trial.

And that is where Robert J. Davis’ book The Healthy Skeptic: Cutting through the Hype about Your Health comes into play. What makes Davis’ book stand out over other books debunking contemporary health claims is that he gives the reader a set of solid guidelines to evaluate scientific statements about health in general. Another major strength is that the author does not single out one group of health hustlers but argues quite persuasively that misinformation about health is not confined to pharmaceutical companies or sellers of dietary supplements, but is rampant among government, non-profit organizations, and consumer activists as well. For example, as  the author writes about consumer activists:

Simply because they’re looking out for our welfare doesn’t necessarily mean that the public interest groups always tell us the truth. Rather than helping us, they can sometimes cause harm by frightening us unnecessarily and diverting our attention from risks that are far more important. As healthy skeptics, we need to apply the same scrutiny to their advice as we give to that from the industry-funded groups or anyone else.

The most “timeless” aspect of the book is the chapter where the author discusses the use and abuse of science in health. Before drawing our wallet or changing our diet, we can ask ourselves the following eight questions:

1. What kind of study is it (laboratory research, short-term human studies, randomized clinical trials etc.)
2. How big is the effect?
3. Could the findings be a fluke?
4. Who was studied?
5. Is there a good explanation?
6. Who paid for the research?
7. Was it peer reviewed?
8.  How does it square with other studies?

As should be clear from those questions, behind the phrase “research proves” are many shades of grey. As the author points out, the question of how a study squares with other studies is perhaps the most crucial question. There is so much (poor) research being published that almost any claim about health can be supported by scientific studies. Sellers of dietary supplements often exploit this by presenting only studies that “support” their recommendations. If health advice does not come with qualifications and/or opposing research conclusions are not mentioned at all, one should be very wary.

Perhaps the most important chapters for life extentionists are those on dietary supplements and “anti-aging doctors.” Davis gives a number of useful recommendations to evaluate claims about supplements:

- Verify “clinically proven” claims
- Don’t assume that “natural” means safe
- Be skeptical of claims that a souped-up or specifically targeted vitamin or mineral supplement is better than an ordinary one
- Don’t be swayed by weasel words (such as “maintains heart health” or “provides immune support”)
- Be wary of organizations or individuals who provide information about supplements and also sell them

When all is said and done, the book does not recommend any radical interventions to improve health or prolong life and sticks to the usual recommendations (don’t smoke, exercise, moderation in eating and drinking, etc.) This is not because of cynicism, but because the more radical claims are just not backed up by contemporary science.

Life extensionists and futurists may believe that they are mostly immune to wishful thinking and the marketing of snake oil but  they may be less immune to more subtle psychological (deadly) traps such as the belief that “this time, things are different,” or the naive assumption that all problems can be solved, given enough time and knowledge. Although progress in science can benefit from scientists that are committed to achieve  important goals like increasing the maximum life span or even defeating death altogether, in reality it is often hard to tell the difference between being motivated by such desires and simply assuming that they will be satisfied, and thus crossing the line into meliorist dogmatic belief.

An interview with the author can be found on the Amazon page for the book.