2.7: Buyer Beware

As discussed in Chapter 1, research results are disseminated very fast, not only to scientists but to the public as well. The public gets selective information and in soundbites—the bottom line without the details. But without the details, one “finding” is given the same weight as another, even when one is flimsy and the other is backed by solid evidence. Scientists approach research findings with “healthy” skepticism. You should too.

If you hear that a study shows that people who take vitamins have fewer cancers (a link), this doesn’t mean that the study showed that taking vitamins lowers the risk of cancer (cause-and-effect). Finding links between what people do and their diseases are jumping off points for further studies. Sometimes the links turn out to be cause-and-effect, sometimes not.

Many links are hard to separate out for study, because health habits, socioeconomic status, etc., are all interlinked. One of the strongest links to poor health is poverty. Poor people in the U.S. are less likely to see a physician when ill, smoke more, have more stress, eat poorer diets, take fewer vacations, subscribe to fewer magazines, have less health insurance, live in more crowded conditions, have less education, have fewer teeth, have older cars, have more cancer and heart disease, and die younger. So, all of these factors are linked. You can say that people who eat poorer diets have more heart disease. Or people who take fewer vacations have fewer teeth. Or people who have less education have more cancer. Or people who don’t subscribe to magazines die younger.

In many cases, statistical adjustments are made to try and separate out a link. If people who drink more coffee are found to have more heart attacks (a link), adjustments for other factors such as smoking have to be made to see if coffee is a separate link. (Smoking increases the risk of a heart attack, and smokers drink more coffee than nonsmokers.) You can adjust for well-established risk factors, but others may be equivocal or unknown. Seventh‑Day Adventists are used in some studies of the health benefits of vegetarian diets. Adjustments are made for their abstention from alcohol and tobacco, but other ways in which they differ from comparison groups also may affect health.

Even if a study shows that taking a certain substance improves health, this doesn’t mean that it will improve your health. A study of a rural population in China showed that those given a supplement of carotene, selenium, and vitamin E had less cancer. The study was well-publicized in the U.S., including a television segment on PrimeTime Live. So many viewers inquired about the exact doses taken in the study, the doses were announced again on the program.

The rural Chinese in the study had a poor diet, with a chronically low intake of several nutrients. They also had one of the world’s highest cancer rates; more than 85% of their cancers were of the esophagus and stomach. Their diet also was unusually deficient in selenium. Their local soil was one of the world’s lowest in this essential mineral,

and most of what they ate was grown locally. Of course they were healthier when given nutrients they lacked! Required vitamins and minerals are, by definition, essential for good health. If you’re already getting enough, taking more won’t make you healthier.

A study mentioned earlier, that aspirin lowered the risk of heart attacks, also got a lot of publicity. Aspirin hampers the formation of blood clots (see Chap. 7), so it would be expected to lower the risk of heart attacks (usually from a blood clot blocking an artery that feeds the heart muscle). The study was done on older male physicians in the U.S. Those who shouldn’t take aspirin (e.g., those with an ulcer or those with risk factors for a hemorrhagic stroke) and those who had adverse effects from aspirin in a trial run were excluded as subjects.

For young men who wonder if they should take aspirin to lower their risk of a heart attack: Your risk of a heart attack is much lower than your risk of bodily injury (see Figure 8‑2)—accidents, gunshot wound, etc.—in which case you want your blood to clot faster!

The 2019 Guidelines of the American College of Cardiology acc.org and the American Heart Association heart.org advise against taking aspirin to lower the risk of a heart attack unless you have a higher risk (e.g., you’ve had a previous heart attack) because of the increased risk of bleeding.

Healthy skepticism also means: don’t go to the other extreme and dismiss studies just because they aren’t perfectly controlled. Suppose you hear that breast-fed babies are found to be healthier and smarter than bottle‑fed babies. Look at the details (e.g., who and how many were studied, how health was measured, whether other relevant variables such as I.Q. of parents were taken into consideration), but don’t disregard the study just because it wasn’t randomized or double blind and only showed a link rather than a cause-and-effect relationship.

In many such studies, it’s the best one can do given the circumstances and funding. In time, such studies accumulate to give a preponderance of evidence of a cause-and-effect relationship— as with smoking and lung cancer.

One can see that huge variations exist in the particulars of a study. It’s no wonder that different studies can come to different conclusions. Some studies “simply” observe thousands of people for years to look for statistically significant links in health habits. Others study a few people intensively in controlled settings. Then there’s the definitive clinical trial, where huge numbers of people are randomized into an elaborately controlled double-blind study.

Consumers must be particular cautious about claims about dietary supplements, since many don’t have any studies to back the claims. Unlike drugs, they don’t have to demonstrate effectiveness or safety before being sold.

Reliable health and science information is hard to sort out from the unreliable. As a group, .gov sites are the most reliable. The information is science-based, updated regularly by qualified scientists, and the sites don’t sell or advertise products. MedlinePlus.gov provides consumer-friendly information on health topics, including drugs and supplements. PubMed.gov is a searchable database of more than 29 million abstracts of studies/articles published in biomedical journals. Most are very technical, and some of the abstracts link to the full articles, such as the more than 5 million available for free on PubMedCentral ncbi.nlm.nih.gov/pmc.

There are also more specific websites, e.g., Office of Dietary Supplements ods.od.nih.gov for information on individual supplements, and the National Center for Complementary and Integrative Health nccih.nih.gov. One can also restrict searches to .gov websites on google by putting in the subject, a space, then .gov in the search bar (e.g., breast cancer .gov).