100 Million Years of Food (22 page)

Most giant roundworm infections do not cause great harm to their human hosts—nor should they, because if they were deadly, we wouldn't be here and neither would they. However, during their epic peregrinations about the body, they may get lost, and that's when the real damage can occur. Giant roundworms have been found in the sinuses, pancreas, bile duct, gallbladder, liver, lower intestines, and appendix; they have caused cardiac arrest; they have exited the body through the ear and vagina, and from the bladder with urination. They can even infect unborn babies; a foot-long male roundworm was once recovered from a newborn child. Giant roundworms can be extracted or expelled with drug treatments, but reinfection is common. Infants, due to their fondness for eating soil, are easily contaminated. Giant roundworm eggs are virtually indestructible, resisting acid, alkaline, dehydration, and toxic salts.
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It's worth contemplating the life of a roundworm, not only because they are a health hazard for billions of people around the world, but because their life cycle helps to explain how the hygiene hypothesis works. If you have the misfortune to acquire a highly specialized parasite, the last thing your body should do is to mount an extremely aggressive defense. The giant roundworm has coevolved with humans for thousands of years, so it is highly resistant to purging, and an inflammatory barrage strong enough to quickly knock out the roundworm would end up destroying innocent surrounding tissue. Instead, the immune system response is toned down to a level more appropriate for a long siege with a wily foe, and as a side effect, other foreign substances, such as grass pollen and cockroach dust, also get treated with kid gloves instead of brass knuckles.
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In other words, long ago in our evolutionary history we struck a kind of bargain—a truce among thieves—with parasites: In return for their not killing us (or not too quickly, at any rate), we grudgingly agreed to host them in our guts and feed them with our blood. Paradoxically, our immune systems became dependent upon early bouts of infectious diseases for proper calibration. Without the crucial intervention of infections, our immune systems remain immature and oversensitive. Truce or no truce, no one likes dealing with thieves, especially the kind that reside in our internal plumbing. A great sweep of hygienic innovations, inspired by the work of Pasteur, Koch, and other scientists—notably the widespread use of antibiotics—virtually eliminated parasitic horrors like giant roundworm from everyday life in industrialized countries, but in its place, spotless households are besieged with allergic diseases, and our former parasites are getting the last laugh.

The hygiene hypothesis, it should be noted, is far from perfect. Why, for instance, do some studies show that infections from a particular parasite alleviate allergic disease symptoms or markers, while other studies on the same parasite find the opposite result? Why do some parasites produce fewer inflammatory symptoms than others? Why are asthma rates decreasing in Western countries?
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Not because environments are becoming dirtier or because families are getting bigger. As for food allergies, no one knows yet if the hygiene hypothesis applies to them; so far the strongest results in allergic diseases have been with asthma and hay fever.
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Despite the many gaps in the hygiene hypothesis, researchers have found that therapeutic infection with parasites can produce impressive improvements in patients with chronic autoimmune diseases. Crohn's disease is an inflammatory disease of the intestines, leading to fever, abdominal pain, diarrhea, weight loss, vomiting, rectal bleeding, arthritis, and painful nodules on the shins. Researchers at the University of Iowa in Iowa City asked participants with Crohn's disease to down a drink with 2,500 pig whipworm eggs floating in suspension, every three weeks, for a total of twenty-four weeks. Pig whipworms were chosen because, unlike their human whipworm relations, they do not infect humans naturally, they hatch in the gut but politely refrain from venturing beyond their environs, and they are expelled after a brief period of colonization. Within three months, almost all of the Crohn's disease sufferers who drank pig whipworm eggs went into remission. Because the participants knew what they were drinking, the researchers could not rule out a placebo effect, but even then the percentages were promising. Dr. Joel Weinstock, one of the authors of this study, points out that Jews may have higher rates of Crohn's disease because they refrain from eating pork, have cleansing rituals, and tend to live in cities far from animals and animal waste, which may displace them from the protection offered by parasitic worm infections.
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Ulcerative colitis, a disease that shares many of the features of Crohn's disease (both are grouped under the heading of inflammatory bowel disease), was also the subject of an experimental study by researchers at the University of Iowa and again produced positive clinical improvement in symptoms. Buoyed by the promising results of these small trials, larger-scale tests on the safety of parasitic worm therapy are now being carried out in Europe and the United States. Other researchers are investigating the applicability of using parasites to battle multiple sclerosis and type 1 diabetes. One day, Mom, Dad, or Doc may pop a couple of thousand FDA-approved whipworm or hookworm eggs into your apple juice (“a worm a day keeps the wheezing away…”) to go with your breakfast. Until then, however, some scientists worry that the message about the hygiene hypothesis is going in the wrong direction and risks undoing decades of public health measures to keep serious infectious diseases at bay.

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.
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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.
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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.

—
C
LAIRE
M
.
C
ASSIDY
, “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.
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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?
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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.
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