Review of Book "The China Study: The Most Comprehensive Study of Nutrition Ever Conducted and the Startling Implications for Diet, Weight Loss, and Long-term Health"

Dr. Campbell's credentials on the subject of nutrition may be matched but cannot be surpassed by anyone in the world. Combined with his own research and supporting references, which take 36 pages, plus sound logic, his admonition for a whole foods, plant-based diet is overwhelmingly convincing and persuasive. There's no need to repeat other readers' laudatory comments.

There are a few points that I wish could be further addressed. The suggestion that we not consume dairy food is based on the unhealthful effect of casein, the primary protein in milk. Numerous research articles have been published since he wrote this book 20 years ago. I checked most references on the Wikipedia page for "casein" related to potential health issues. Those that have found no health risks are now marked with disclaimers as a standard in scientific publication, typically claiming to have no connection with a commercial entity. That used to be a serious problem when Dr. Campbell wrote the book (see the part "Why haven't you heard this before?"). I believe flagrant violation of ethical rules has died down in the past few decades. In short, more research is needed to confirm or disprove the harm done by casein, or dairy foods in general.

Secondly, an unconditional attack on reductionism is not warranted. Science progresses by synthesis for sure, but more by analysis and reduction. Whole food is healthy and we all should embrace it. But it doesn't mean we should stop pursuing the science of finding the reason why any food, whole or not, is good or bad. Just because we can't narrow down to a few manageable ingredients out of a thousand in today's research doesn't mean we should give up in that direction for good, especially considering that food science may benefit from AI just as other branches of biological and medical sciences do. Reductionism is a fundamental principle in modern science, including nutrition studies.

Having said that, personally, I heed Dr. Campbell's advice and have adjusted my diet accordingly. I've long had in my mind a personal healthfulness rank of animal food, i.e. fish > chicken > pork > lamb ≈ beef. Now I completely avoid beef and lamb, greatly greatly reduced intake of pork, and cut down on chicken. But I still eat fish once in a while, because, well, I'm also a fan of Dr. Andrew Weil, another trustworthy health advocate, and because fish is a big part of Mediterranean and Japanese cuisine. I have changed the cow milk:soy milk ratio of about 3:2 to 2:3, and mostly changed Greek yogurt back to regular yogurt, as Greek yogurt contains more casein, even though I have some doubt about the health issues about casein as I said. Needless to say, I have significantly increased intake of various vegetables and further diversified my choice of vegetables and fruits. In case you missed one point while reading the book: Dr. Campbell has provided us a simple solution to the dilemma that you like to eat a lot of tasty food but don't like to gain weight by eating a lot, and the solution is to eat plant-based food so you can eat it to your heart's content and still maintain your weight. For this as well I do appreciate his wisdom.

Trivia: Some readers complain about the title of the book, because the China Study is only part of the book. According to Dr. Junshi Chen, the counterpart on the China side of this study, the book title was given by the publisher, so it's not that Dr. Campbell is a fan of clickbait. Also, there's one person in the book who is undervalued. Dr. Gopalan and his team published an important paper on aflatoxin in a little known journal in 1968 (Ref.13 of Chpt 2, 16 of Chpt 3). While Dr. Campbell acknowledges the significance of this research, it's worth pointing out that Coluthur Gopalan (1918-2019) is hailed as the Father of Indian Nutrition Science.

(originally published on Goodreads)

Two types of biological sexes and Olympic Games

The most common definition of biological sex is based on physical structure or morphology, but some definitions also include chromosomes. The two types of biological sexes are called phenotypic gender and genotypic gender, respectively. There are a very small number of people whose two types of gender are different from each other, which can cause some confusion. It is necessary to point out in what situations each of the two gender types should be used. Phenotypic gender is almost always the same as the gender assigned at birth because it is easy to determine. If a person's genotypic gender differs from it, he or she will grow up and participate in various activities without knowing it throughout his or her life (unless genetic testing is done). It is the genotypic, not phenotypic, gender that determines secretion of hormones, including testosterone and estrogen, determines some physical attributes, muscle mass, explosive power, etc.

Therefore, for people with the two types of biological sexes having different values, when gender must be specified, different gender types should be used for different occasions. For example, phenotypic gender is often used for surgery, genotypic gender for prescriptions, and should also be used for registration for sports events from now on. The International Boxing Association (IBA) determines gender by genotype. In a letter to the International Olympic Committee (IOC) in June 2023, they pointed out that Algerian boxer Imane Khelif had XY (male) chromosomes in two separate tests, and therefore disqualified her (him) from participating in the 2023 International Boxing Championships. The letter stated, "This situation epitomizes the importance of protecting safe sport, and the integrity of sport in which the Olympic Movement is jointly committed to." Unfortunately, the IBA did not disclose the test results. Meanwhile, the IOC accused the IBA of defaming the IOC. As a result, the IBA's test results were ignored by the IOC, and some athletes who may have XY chromosomes are allowed to participate in the women's events of the 2024 Olympics. It is regrettable that as a tradition, the Olympic Committee still determines gender based on the sex assigned at birth, i.e. phenotypic gender. For the very few who have a different phenotype from their genotype, XY chromosome athletes clearly have a greater advantage in participating in women's events. (Similarly, athletes with XX chromosomes but of phenotypically male gender are at a disadvantage in participating in men's events, although this may never actually happen, for obvious reasons.)

The cost of sex chromosome testing is currently as low as $50, and the average price per person may even be lower if we exempt the athletes who were tested before and exclude certain events that do not need this test. In four years, the Olympic Committee rakes in $7.6 billion. With this income, XY/XX chromosome testing on participating athletes should be routine. The ancients did not know about genes, much less the fact that it is genotypic gender that determines the male hormones which boosts performance in competitive sports (they didn't know because in most cases, this gender is the same as phenotypic gender). But in the second decade of the 21st century, it is high time we corrected this mistake. After all, unfairness in women's competitive sports caused by the XY chromosomes of the few is no less than or perhaps even greater than doping. In sports of body contact such as boxing, there is an added layer of concern, that is safety of the athletes.

Let me reiterate. There are two types of biological sexes. It's horrible to say that biologically male athletes should not compete with female athletes. We must say genotypically male, or as British biologist Dr. Richard Dawkins said, "genetically male boxers should not fight women" (my italics). Dr. Dawkins's Facebook account was deleted because he didn't make it clear to agitated readers as well as muddle-headed Facebook censors that his word "genetically" must not be replaced with the ambiguous "biologically", as those supporting or condemning him did. Once this distinction is made, it becomes clear that we are only advocating the unambiguous definition of gender based on genotype for competitive sports only, leaving the choice of the type of gender, genotypic or phenotypic, alone in other aspects of life. And at the same time, we should respect those people who have one type of gender different than the other, unconditionally in all circumstances. They are one type of intersex or bisexual people, but they are normal human beings just like everyone else.

Excess leads to harm on the same metric as benefit from moderation

Moderation is the key to health. For example, sunbathing can help synthesis of vitamin D in the body, but excessive sunbathing increases the risk of skin cancer. Resistance exercise can help increase muscle mass, but excessive exercise causes muscle strain. These excesses have one thing in common: the harm they cause is not on the same metric as the benefit brought about by the moderate use. For example, too much sun exposure will not actually reduce the synthesis of vitamin D. Excessive resistance exercise itself will not lead to muscle atrophy.

So, are there behaviors or food intakes where overdoing creates the opposite result on the same metric as doing it in moderation? Here is an example:
Can Eating Mangoes Reduce Women’s Facial Wrinkles? Pilot Study Shows Promising Results
A 2020 randomized clinical trial at the University of California, Davis, found that eating 85 grams of mango per day can reduce facial wrinkles, but eating 250 grams can increase wrinkles. The experiment described in the research article is simple and was well done. As for why increasing the intake of mango several times will cause increase in wrinkles, the researchers can only guess: It may be related to the large amount of sugar contained in mango. This guess is not very convincing, but there is currently no better explanation. The paper has been cited in other articles over the past two years, but the test was not further studied by any other team.

The above test only examines one indicator: the amount of facial wrinkles. Moderate intake and excessive intake of mangoes produce opposite results on the same indicator. It is not that excessive intake causes some damage unrelated to the indicator, nor is it that large intakes reduce the amount of wrinkles more, or reach a peak (i.e. Mango intake is no longer associated with wrinkle reduction). I don’t know if there is a special term for this type of test results in epidemiology, but it is certain that such test results are not common.

Another benefit about red meat

Red meat, most typically beef, but also including some others such as pork in spite of its white color after cooking, has had a bad reputation in recent years. International Agency for Research on Cancer (IARC) of the World Health Organisation (WHO) classifies red meat as probably carcinogenic to humans, but scientists caution against misreading of the news. Consumers should not rush to conclude that eating even a moderate amount of red meat is bad. In fact, unlike certain things some of us may intentionally or unintentionally consume, e.g. tabacco, or mercury, which have no safe low limit, red meat with a moderate intake is good to us because it is very rich in nutrition, especially protein.

Now, a new research, published in Nature has just found that red meat, as well as dairy products, can boost cancer therapies. More amazingly, the research even found benefit in trans-fat, which we have for quite some time regarded as a heinous villain against our health. On the other hand, reading this research, we must keep in mind that red meat is said to boost certain cancer treatments and the specific type of trans-fat is involved, but this definitely does not suggest we should eat a significant amount of red meat or even a small amount of trans-fat, because (1) this research is still new, and (2) the cancer treatments in this research are specific, at least for now. Nevertheless, this research is something we may keep an eye on because it sheds new light on our conventional wisdom.

East Asians more likely to carry a gene variant associated with long COVID but ...

According to a preprint research article Genome-wide Association Study of Long COVID, "[t]he allele frequency of rs9367106-C at the FOXP4 locus varied greatly among the different study populations, with frequencies ranging from 1.6% in studies with non-Finnish Europeans to higher frequencies such as 7.1% in Finnish, 19% in admixed Americans, and 36% in East Asians". In other words, non-Finnish Europeans have a 1.6% chance to have this gene variant associated with an increased risk of Long COVID and East Asians have a 36% chance. This is clear enough. But some people misread these simple numbers. One journalist's article LONG COVID GENE FOUND says that "[t]he Long Covid FOXP4 mutations are 7x more common in Finnish people than in non-Finnish Europeans, and 36x more common in East Asians". The author must be interpreting the ratios in the research paper as a number (numerator) over some unit denominator. But if we do care about an inter-race comparison, we ought to say that the mutations are 7.1/1.6=4.44 times more common among the Finnish people than non-Finnish Europeans, not 7 times more. Likewise, East Asians are 36/1.6=22.5 times, not 36 times, more likely than the non-Finnish Europeans to have this mutation.

When that journalist's English article was translated into Chinese and posted to Weibo, the Chinese Twitter-like social media network, an even worse headline was added, "东亚人患新冠长期后遗症的概率是欧洲人的36倍" (East Asians are 36 times more likely than Europeans to suffer from Long COVID), naively equating the ratio of carrying a gene variant to the ratio of getting the disease, a mistake I pointed out in my Weibo posting (along with the Chinese translation). If the doctor of Angelina Jolie, the actress who opted for mastectomy to forestall a possible breast cancer, had told her she would definitely get breast cancer because she carries that gene, he could be instantly famous among the cancer researchers world wide, as a laughing stock.

So, what is the chance of getting long COVID for each race? According to a February 14, 2023 article summarizing data from the US census, Asian Americans are the least likely to get long COVID among the five race categories. However, Asian Americans with long COVID have the highest chance to experience severe symptoms. To put simply, Asian Americans don't easily get long COVID, but if they do get it, their symptoms are very serious, relative to any other race. It would be interesting to reconcile this data with the latest research about the gene variant. It's possible that Asian Americans, the relatively well-educated and well-off group of Americans, follow common hygiene practices better than other Americans, hence lower rate of COVID and therefore long COVID. But due to the FOXP4 gene variant which many East Asians carry, long COVID causes the most severe symptoms to East Asians. There are still missing links in this logic, though. For example, Asian Americans are not necessarily East Asian Americans.