100 Million Years of Food, page 17
Vaccines are of great interest in this regard. The logic of the hygiene hypothesis suggests that vaccinations should increase the risk of allergic diseases by removing childhood infections. Although there is preliminary evidence for this possibility—vaccinations against a species of bacteria responsible for respiratory tract infections may increase the chance of getting asthma, whereas chicken pox infections in early childhood may reduce the likelihood of eczema and asthma—most doctors strongly support vaccinations, arguing that the dangers of measles, mumps, chicken pox, and other classic childhood diseases greatly outweigh the risk and inconveniences of allergic diseases.54 Some parents may fret about the consequences of mercury and aluminum in vaccines in promoting diseases such as autism, but the 1998 study that originally sparked questioning about the link between MMR (measles, mumps, and rubella) vaccine and autism has been thoroughly discredited for manipulation of data, and the principal author of the study, the British doctor Andrew Wakefield, was stripped of his license to practice in the U.K. in 2010. Nonetheless, many people remain confused about the safety and efficacy of vaccines, which has led to an alarming jump in the prevalence of once-uncommon contagious and potentially deadly infectious diseases like measles and whooping cough among children in industrialized countries.
Ironically, while many scientists worry about the sharp rise in preventable infectious diseases, other individuals worry that bureaucratic inertia is bogging down the release of parasitic medications that could rapidly alleviate their serious allergic and autoimmune diseases. For a few thousand dollars, a person can cut the red tape and buy pig whipworm or hookworm eggs online today from shrewd enterprising companies. Down the road, when FDA-approved parasitic medications finally hit the market, they will provide a measure of safe relief for allergy sufferers.55
These kinds of regulatory innovations will take time to implement. In the meantime, for parents concerned about the possibility of allergies, giving children more exposure to sunlight, lessening dependence on the use of antibiotics and antibacterial hand soaps, and achieving a better balance of omega-3/6 fatty acids through increased consumption of animal fats and/or decreased consumption of omega-6-heavy vegetable oils (such as corn oil) are practical measures that plausibly decrease the risk of allergic disease.
Meanwhile, to prevent common infectious diseases like measles from regaining a foothold in our societies, parents should continue to follow the advice of doctors and vaccinate their children. The case of vaccinations is a good example of the limits of applying evolutionary theory to everyday health: Although our bodies were adapted for exposure to nasty bacteria, viruses, and other parasites, it simply doesn’t make sense to reinvite that nasty crowd back into our living rooms. It is more sensible to give scientists time to find harmless parasites to calm our immune systems down, and to let our children hang around farm animals in the meanwhile.
THE CALORIE CONUNDRUM
[In a 1987 study by Drewnowski and Yee] 90% of American boys were dissatisfied with their weights, the same number as among girls, but whereas all the girls wanted to weigh less, half the boys wanted to weigh more.
—CLAIRE M. CASSIDY, “The Good Body: When Big Is Better”
Ravens dot the wintry sunset over Sapporo. I scurry past precipitous snowbanks and walk-skate across a treacherous icy street. A staircase leads down into a shopping mall under the central train station. Shop windows gleam with fastidious replicas of Japanese delicacies: lacquered bowls bearing buckwheat or rice noodle soup and slices of fatty pork, rice topped with bright yellow omelets and rivulets of mayonnaise or ketchup, pork bones moored in curry stews. My stomach growls at the odors wafting out of the shop entrances, but because the first installment of my university researcher’s salary will not be paid out until the end of the month, I keep walking, looking for something cheap and filling.
I start to feel woozy from pacing up and down the corridors on an empty stomach. From the depths of my despair, I spy a lavish poster: In shiny pictures—for such is the extent of my command of the Japanese language—it promises a three-course meal, including miso soup, a salad, and a bowl of rice topped with salmon roe, for only 700 yen, or $8.50! I nearly weep in relief as I march into the restaurant, unperturbed by the upscale office workers gathered inside, the posh wood furnishings, the waitress smartly dressed in a traditional outfit. An advertised bargain is iron-clad, a penny saved with a hot meal to boot. Isn’t life sweet? After I squeeze onto a free chair at the bar, I am handed a leather-backed menu. Hmm. Most budget eateries that I frequent offer menus consisting of plasticized home-office printouts, but no matter, a special is a special. I flip through the pages but cannot find the meal combo advertised on the window. I keep flipping through the pages. It is hot inside the restaurant; I am still wearing my bulky, frayed, fifteen-year-old industrial-green winter parka. I search in vain through the pricey offerings. I gesture at the window and explain in my best broken English, “Food–special–window–outside?”
The waitress shoots back without a hint of a smile, “Lunchtime only.”
Oh dear. Far too late to make a discreet exit. Two women have ceased their chatter to survey the foreigner in an awkward predicament. Sweat starts to pour down my back and forehead, and my armpits begin to release alarm pheromones. What to do? Trying to mask my agitation, I flip through the pages again, front to back, back to front. I point to the cheapest offering I can find.
An Osaka salaryman next to me strikes up a conversation. Presently, the waitress places in front of me a fist-sized serving of rice, topped with a smattering of salmon roe. The salaryman and I both stare in astonishment at my dinner. He, evidently, is traveling on a business expense account, for he has ordered the same rice, plus a bowl of soup, a side of marinated fish, a salad, a frothy omelet, and a tall bottle of Sapporo beer. I fantasize what my restaurant meals would have been like if I had sold my soul to the corporate world instead of miserly academia. The salaryman asks with a note of incredulity, “That’s all?”
“I’m not hungry,” I reply, trying to sound convincing.
As I discovered after moments of humiliation like this, food in Japan is expensive, due to a confluence of high transportation and labor costs, limited growing season, shortage of arable land, and import barriers. At the other end of the cost spectrum, Americans enjoy access to the cheapest food in the world relative to income.1 True, bargains in Sapporo can be ferreted out here and there, like generously proportioned okonomiyaki pizzas made of cabbage, dough, and squid, with a squirt of mayonnaise, served up by a trim sixty-year-old chef just beyond the university gates, or brisk ramen noodle shops and rice bowl joints that take orders through vending machines that dispense meal tickets. In Los Angeles, on the other hand, when my college friends and I were hungry, we could order a heaping, steaming, savory plate of noodles, pork, and veggies, plus a beer, in bustling Thai Town; stuff our faces with pancakes, eggs, and sausage at Denny’s; grandly feast on Mexican-style rice, black beans, lettuce, shredded pork, and salsa at Chipotle’s; or fill our stomachs on a never-ending parade of salad, soup, pasta, pizza, sourdough bread, baked potatoes, bland apples, and ice cream at Souplantation, all for an astonishing ten bucks or less. No wonder the average Japanese man eats around three hundred fewer calories per day than his American counterpart, less than even the Chinese. The Japanese also have longer life spans than Americans and Chinese. Could the smaller food portions of Japanese have something to do with this?2 In the never-ending discussion of diet and health, the debate often comes back to calories. Is the amount we eat killing us? The answer is surprising and may have a profound impact on the way we choose to eat and live.
In a succession of experiments carried out since the 1930s, it has been observed that reducing the amount of food that animals eat causes some species to live longer. This “calorie restriction” effect has been found in diverse species. In 2009, the prestigious peer-reviewed journal Science published an article that seemed to seal the case for human participation in calorie restriction: In a two-decade-long Wisconsin study, monkeys that had been allowed to eat as much as they wanted died from diabetes, heart disease, and cancer at a faster rate than monkeys that had been allowed to eat just 70 percent of the calories permitted to the first group. Is this a no-brainer? Overeating kills, so is it time to get serious about cutting the calories? Many people have already reached this conclusion and voluntarily maintain a diet of reduced portions. However, there are a few wrinkles in this line of thinking. Although many scientists endorse the principle of calorie restriction, others are skeptical because the evidence on calorie restriction with humans has been minimal.3
Meanwhile, Shinichi Nakagawa and his colleagues at the University of Otago in New Zealand perused the results of more than a hundred calorie restriction experiments and noticed four surprising themes. The first is that the longevity benefit from reducing calorie consumption has been demonstrated mainly in animals that were bred for laboratory conditions: rats, mice, fruit flies, and yeast. Many wild animals have been tested, including fish, grasshoppers, and moths, but these don’t show the same dramatic improvement in life span when their food portions are reduced. No one knows why this is the case, but lab animals live in a peculiar world where food is never scarce, and thus some important pathway in their physiology may have been altered or lost through generations of controlled breeding. A lab animal’s appetite is uncoupled from the demands of life in a natural setting. By contrast, wild animals may be like Swiss timepieces, exquisitely honed by evolution to eat the right amount of food. It could be argued that humans in industrialized regions have also been exposed for many generations to conditions where food is in abundant supply, and therefore the calorie restriction effect might still apply to us—in other words, our genes may have more parallels to the genes of lab-bred rats and mice than to those of wild animals.4
The second wrinkle of the calorie restriction effect is that the life-lengthening result of calorie restriction is overshadowed by an even stronger impact from protein reduction. In other words, if you’re looking to pump more days into your life, cutting back on calories while increasing your protein intake may end up accomplishing nothing, but keeping your calorie intake constant while reducing meat and other protein sources may be the clincher. Reducing protein intake causes a decline in IGF-1 circulating in the human bloodstream, which may turn out to be a good thing, because IGF-1 has been linked to increased risk of prostate and premenopausal breast cancer.5
A third recurrent theme is that a reduction in calories and protein brings benefits only up to a certain point; after that, if calories and protein continue to be eliminated, the organism will begin to suffer adverse health. There exists a sweet spot, an optimal intake level of calories and protein where life span is maximized. In studies, cutting calories to half of the organism’s preferred intake and slashing protein by two-thirds yields longest life. Remember, these are estimates carried out across all species, including the laboratory animals that exhibit the strongest results from calorie reduction. For humans, the optimal levels of calories and protein may turn out to be different.6
The fourth issue to consider is that females tend to reap more benefit from calorie restriction than males. This amply documented sex difference has a worrisome implication: Cutting back on calories probably causes sexual desire to evaporate. Proponents of calorie restriction (they seem to be mostly men) are understandably less than eager to draw attention to this effect. The best argument thus far about why calorie restriction increases longevity is that extended hunger causes animals’ bodies to switch priority from reproducing to prolonging life. It’s analogous to a bear’s instinct to hibernate through a long winter rather than waste energy by lumbering around a snowy forest searching for nonexistent food and mates. Many scientists believe that food deprivation similarly triggers a diversion of energy away from hopeless activities such as trying to conceive when a mother has barely enough food reserves to keep herself alive, instead channeling those scarce calories into repairing the body and conserving energy for a better opportunity down the road, when food finally comes hopping down the path or sprouts from a branch.7
For females, holding off on babies yields a jackpot of savings in energy. For males, on the other hand, having sex now or later does not entail a dramatic shift in physiological effort. The bodies of males may therefore be geared to smaller increases in longevity when food intake is reduced.
As you can see, the edifice of this theory is erected, so to speak, on the axiom that calorie restriction shifts priorities from reproducing now to reproducing later. Besides draining sexual urge, half-starving yourself will transform you into an ill-tempered ogre. Not surprisingly, taking food away from animals makes them aggressive. I remember an occasion when my family was tardy in feeding the house cat. When I finally brought out its plate, rather than being grateful, our normally placid cat leapt at me and scratched my leg. If people who are well fed view society on benevolent terms, as they are forced to forgo greater quantities of food, their circle of sympathy will steadily shrink, from society to friends to family to close family, and finally to the self alone.8
To rub barbecue salt into an open wound, the latest round of news for calorie restriction boosters is a tad gloomy. A second set of monkeys is currently being tracked by the National Institute on Aging (NIA) in the United States, and the results so far, released in the fall of 2012, indicate that shaving calories didn’t help hungry monkeys gain extra years compared to well-fed monkeys. However, this most recent NIA experiment compared fit versus scrawny monkeys, while the previous Wisconsin study compared overweight versus scrawny monkeys. There may be only a slight difference in longevity between being fit and being scrawny (both are relatively healthy states), but a considerable difference between being fit and being overweight.9
Even if you’d rather eat ice cream while scientists quibble and the members of the Calorie Restriction Society practice dietary austerity, you may want to consider putting your dog on a diet. In a study of Labrador retrievers, half were allowed to eat until they were sufficiently (but not over-) fed, while the other half were allotted three-quarters this amount of food. By the time all the well-fed Labs had passed away (the last one survived to thirteen years, a ripe old age in dog time), nearly 40 percent of the underfed dogs were still alive (and irritably waiting, one presumes, to be fed).10
Although critics argue that the longevity benefits from calorie restriction are underwhelming, almost all scientists agree that the physiological effects are generally positive: These include reduced incidence of the most common human chronic diseases (diabetes, cardiovascular disease, and cancer), slowdown in cognitive decline, and lower levels of cholesterol, triglycerides, glucose, and insulin. The chief drawbacks are that a calorie-restricted animal stops growing, becomes less fertile, and is more vulnerable to cold and some infectious diseases. Taken to an extreme, calorie restriction imposes psychological and physiological side effects that few people would be willing to tolerate, but even a modest 10 percent reduction in calories—from buffet-style consumption to eating just enough to maintain constant body weight—is a supremely cost-effective ticket to a bonanza of health benefits.11
*
Although today the chief concern of many people in industrialized societies is reducing calorie consumption, for other places in the world the great struggle is avoiding starvation, and this was even more true in the past. This observation may seem banal, but an examination of the history of calorie consumption turns out to be fascinating. By examining this history, we can gain a better idea of why many people today struggle with health problems linked to calorie consumption, particularly obesity.
A few thousand years ago, if gamblers had wagered on which society would first beat the scourge of famine and rack up the caloric intake, the safe choice would have been the Chinese, based on their vast agricultural knowledge. The Chinese knew how to treat poor soil with organic wastes, ashes, manure, human waste, and river silt.12 By AD 0, they replaced slash-and-burn agriculture with complex crop rotations.13 They knew how to mix crops using plants like broad beans and ferns, and by the sixteenth century, they knew about the application of potash (minerals that contain potassium) and oil cake (the residue from seeds pressed for oil). Their authorities advocated plowing in the burned stubble from harvests. Through meticulous experimentation and refinement of farming practices, China was able to support a population of more than 100 million people in AD 1124; in comparison, the population of England, at under a million, was around the size of a large Chinese city.14
At first glance, the path of agriculture in the West seemed similar to China’s, albeit slower. Through trial and error, and observation, the Romans learned to employ chalk, dung, and ash and to intercrop lupin (a kind of legume), beans, vetches, and clover. After the collapse of the Roman Empire, crops were changed from two-field rotation to three-field, then four-field rotations of corn, clovers, grasses, and fallow cropping. Inland oceans and rivers provided convenient highways for commerce, and the riches gained from trade propped up a social class that was interested in further profit and the technical means of increasing that profit. The decimation of the European population from the Black Death in the fourteenth century—likely introduced by rats from China, ironically—broke the static pattern of manorial serfdom and freed the gentry to exploit their lands for profit. The disparity in wealth also guaranteed that while some people worked continuously and lived in poverty, others had the time and means to engage in scientific inquiry.
