This is a book about chemistry. It is a book about how science is done. It is a book about humor--I would say, mostly a big attempt at humor. I appreciate some humor in a science book--but rarely do I find a book like this one, where humor seems to be more important than the supposed subject of the book. For example, he writes, "You have to see the best in people, but you also have to be kind of an asshole. Don't worry, it's really fun." While the subject matter in the book is excellent, and the author, George Zaidan, has excellent qualifications as a chemist, I would have preferred a book that did not try so hard to be funny.
Nevertheless, the book covers a lot of fascinating topics; How bad are processed foods? Is coffee good or bad for you? Is sunscreen safe? I learned a lot; what follows in this review is a summary of some of the most gripping topics.
Dry foods and spices are almost devoid of water, so they are inhospitable to bacteria and spoilage. Honey is almost devoid of water (15%), so it also lasts a long time before spoiling. In fact, historically honey has been used as a preservative. The residual water in honey is attached to sugars, so it is not available to microbes.
There is considerable discussion of the distinctions between unprocessed, processed, and ultra-processed foods. The distinctions are not sharp. For example, honey is highly processed--but by bees, not by humans. It is difficult to assign a level of processing. The number of ingredients in a food is not a good method for evaluating the level of processing, or the healthiness or safety of a food.
Zaidan does an excellent job of explaining the two meanings of the word "theory". There is a popular meaning, where any wild idea that someone thinks up as an explanation is called a "theory". And then there is the opposite meaning, used in science, where in order to be called a theory there must be a preponderance of observational evidence built up over a period of time.
Zaiden discusses whether e-cigarettes are "safer" than regular cigarettes. Proponents of e-cigarettes and vaping like to point out that they contain far fewer harmful ingredients. However, the number of harmful ingredients in a product is not correlated with a harmful effect. For example, a single chemical--like cyanide or formaldehyde--can be deadlier than lettuce, which has thousands of chemicals. So, instead of comparing the relative safety of e-cigarettes with regular cigarettes, they should be compared with the safety of breathing fresh air.
The book goes into detail about the efficiency of sunscreen--it is quite efficient--and its side effects. The book also discusses the gross mistakes made in the original study of the Mediterranean diet.
Quite a large part of the book is about science itself, and the multiple potholes that get in the way of good nutritional epidemiology. For example, there is an excellent discussion of the perils of statistical associations, commonly known as "p-hacking." Other potholes have to do with people's poor memory in observational studies, and confounding associations. Small increases or decreases in risk are not reliable, because of hundreds of associated variables.
The book concludes that ultra-processed foods have not yet been proven to be an important cause of obesity and diabetes. It may be a contributing factor, but it is not known yet. One cannot yet make a reliable quantitative risk assessment of eating ultra-processed foods. However, one might be wise to avoid ultra-processed foods; it's better to be safe than sorry.
The book discusses life expectancy, and what can be done to extend your life. Statistically, in order to extend your life expectancy by three years, you need to do all three of these things:
1) Lose 5 BMI units
2) Cut back from 20 to 10 cigarettes per day (but what if you are already not a smoker?)
3) Increase physical activity from 2 to 4 hours per week.
The book gives some generally applicable advice:
1) Ignore most news about food and health, with the exception of notices about contamination
2) Don't smoke.
3) Be physically active
4) Eat healthy
The book closes with a hilarious analysis of experiments where people outside of a hospital were given the first names of otherwise anonymous patients, and were asked to pray for them. Yes, praying actually helped. But it probably was not statistically significant. There may have been a small correlation between prayers and surgery outcomes--but what is the causal mechanism? Quite a fun analysis!