Illustrations by Knickerbocker
Posted on 05/04/2003 6:46:19 PM PDT by Pharmboy
Illustrations by Knickerbocker
A trip to the diet doc, circa 2013. You prick your finger, draw a little blood and send it, along with a $100 fee, to a consumer genomics lab in California. There, it's passed through a mass spectrometer, where its proteins are analyzed. It is cross-referenced with your DNA profile. A few days later, you get an e-mail message with your recommended diet for the next four weeks. It doesn't look too bad: lots of salmon, spinach, selenium supplements, bread with olive oil. Unsure of just how lucky you ought to feel, you call up a few friends to see what their diets look like. There are plenty of quirks. A Greek co-worker is getting clams, crab, liver and tofu -- a bounty of B vitamins to raise her coenzyme levels. A friend in Chicago, a second-generation Zambian, has been prescribed popcorn, kale, peaches in their own juice and club soda. (This looks a lot like the hypertension-reducing ''Dash'' diet, which doesn't work for everyone but apparently works for him.) He is allowed some chicken, prepared in a saltless marinade, hold the open flame -- and he gets extra vitamin D because there's not enough sunshine for him at his latitude. (His brother's diet, interestingly enough, is a fair bit different.) Your boss, who seems to have won some sort of genetic lottery, gets to eat plenty of peanut butter, red meat and boutique cheeses.
Nobody is eating exactly what you are. Your diet is uniquely tailored. It is determined by the specific demands of your genetic signature, and it perfectly balances your micronutrient and macronutrient needs. Sick days have become a foggy memory. (Foggy memory itself is now treated with extracts of ginkgo biloba and a cocktail of omega-3 fatty acids.)
''Ultimately, the feedback you'll get will be continuous,'' says Wasyl Malyj, an ''informatics'' scientist at the University of California at Davis working with the new Center of Excellence for Nutritional Genomics, who is helping me blue-sky here. The appeal of this kind of laser-targeted diet intervention is hard to miss. If you turn out to be among the population whose cholesterol count doesn't react much to diet, you'll be able to go ahead and eat those bacon sandwiches. You'll no longer be spending money on vitamin supplements that aren't doing anything for you; you'll take only the vitamins you need, in precisely the right doses. And there's a real chance of extending your life -- by postponing the onset of diseases to which you're naturally susceptible -- without having to buy even a single book by Deepak Chopra.
This, then, is the promise -- and the hype -- of nutritional genomics, the second wave of personalized medicine to come rolling out of the Human Genome Project (after pharmacogenomics, or designer drugs). The premise is simple: diet is a big factor in chronic disease, responsible, some say, for a third of most types of cancer. Dietary chemicals change the expression of one's genes and even the genome itself. And -- here's the key -- the influence of diet on health depends on an individual's genetic makeup.
How does that work? Consider what happens, biologically, when we eat a meal. Until quite recently, most scientists thought food had basically one job: it was metabolized to provide energy for the cell. Indeed, that is what happens to most dietary chemicals -- but not all of them. Some of them don't get metabolized at all; instead, the moment they're ingested, they peel off and become ligands, molecules that bind to proteins involved in ''turning on'' certain genes to one degree or another. A diet that's particularly out of balance, nutritional-genomics scientists say, will cause gene expressions that nudge us toward chronic illness -- unless a precisely tailored ''intelligent diet'' is employed to restore the equilibrium.
Take genestein, a chemical in soy, which attaches to estrogen receptors and starts regulating genes. Different individuals may have estrogen receptors that react to genestein differently. Genetic variations like that one, some scientists say, help explain why two people can eat exactly the same diet and respond very differently to it -- one maintaining his weight, for example, and the other ballooning.
There is a buzz around nutritional genomics at the moment, which is partly a matter of timing. A sea change is under way in the approach scientists are taking to disease -- they're looking less to nature or nurture alone for answers, and more to the interactive symphony of ''systems biology'' that nutrigenomics epitomizes.
At the same time, chatter around this new science has been amplified by a controversy. The idea of the biological relevance of race -- even its very existence -- is hotly debated. And the assumption of real genetic markers that distinguish one ethnic group from another is at the philosophical heart of nutrigenomics.
Here's the most familiar example: If you're of Northern European ancestry, you can probably digest milk, and if you're Southeast Asian, you probably can't. In most mammals, the gene for lactose tolerance switches off once an animal matures beyond the weaning years. Humans shared that fate as well -- until a mutation in the DNA of an isolated population of Northern Europeans around 10,000 years ago introduced an adaptive tolerance for nutrient-rich milk. The likelihood that you tolerate milk depends on the degree to which you have Northern European blood.
''That, essentially, is the model -- a very dramatic one,'' says Jim Kaput, the founder of NutraGenomics, a biotechnology company. ''As humans evolved, and as our bodies interacted with foods on each of the continents, we sort of self-selected for these naturally occurring variants. And certain populations have variants that, when presented with Western-type food -- which is usually fatty and overprocessed and high in calories -- pushes them toward disease rather than health.''
Plenty of examples bear out this ill fit between certain cultures and certain diets -- suggesting, if not quite proving, some interplay of genes and nutrition: the Japanese who relocated to the United States after World War II soon saw their cholesterol levels soar. The Alaskan Inuit, whose metabolism was perfectly suited to moving around all day, looking for high-fat food, were suddenly saddled with an evolutionary disadvantage when they began living in heated homes and traveling on snowmobiles, and they now show high levels of obesity, diabetes and cardiovascular disease. The Masai of East Africa have developed new health problems since they abandoned their traditional cattle-meat-and-blood-and-milk diet for corn and beans.
The cradle of nutrigenomics is the cradle of humankind itself: the original migration out of Africa created widely separated subpopulations with distinct collections of gene variants. The members of each subpopulation tend to respond similarly to diet and environmental conditions. But the genetics of race is an inexact science. And since many people have ancestors from different continents -- making them a genetic admixture -- the data are rarely clean-cut. In other words, ethnicity is relevant to nutritional genomics, but only as a starting point. Which is why the idea of sorting ourselves by race and pursuing a diet consistent with the original continental diet isn't going to be very helpful. And why, in fact, the customized diets of most people's perfect genomic future will probably not be all that different from one another.
Kaput estimates that the middle 60 percent of the bell curve are probably not going to need to deviate too much from the basic fruit-and-vegetable-heavy diet recommended by the Department of Agriculture. The folks who will benefit from customized nutritional packets, he says, will be the 20 percent at either end: those at the top who don't have to worry much about what they eat -- and will thus be able to cut corners -- and the 20 percent on the bottom, who respond disastrously to conventional diets and will discover that they need to follow special diets or eat specific supplements. The problem for everyone will be figuring out where they fall on the curve of each disease profile.
Just how far in the future are we projecting here? When will nutrigenomics be ready for public consumption? Even many of those who have faith in the science concede that the staggering complexity of interactions among genes, and between genes and the environment, will be a real challenge to solve. As a workable concept, ''eat right for your genotype'' may be a decade or two -- or more -- down the road.
''Right now, no one in their right mind would offer genetic testing or tell you what drug to take,'' says Dr. Muin Khoury, director of the Office of Genomics and Disease Prevention at the Centers for Disease Control. Despite that warning, a handful of companies are already offering genomics profiles and nutritional supplements to early adopters looking for an edge. One company, the North Carolina-based Great Smokies Diagnostic Laboratory, offers a genetics-testing service called Genovations. Clients pay up to $1,500 for a preventive health profile.
For nutrigenomics to realize its potential, though, vast, ethnically diverse databases of genomic profiles will have to be assembled, from which researchers will try to divine patterns.
But that, of course, opens up a whole new can of genetically modified worms. Once our genotypes are in databanks, can we really be sure they won't be sold to employers or insurance companies? And in what social gulag will those poor saps find themselves who simply cannot resist tucking into a double-cheese all-beef sub during the seventh-inning stretch?
Bruce Grierson is a writer in Vancouver. His last article for the magazine was a profile of J. J. Goldstein, a teenage spelling champion.
Copyright 2003 The New York Times Company
It's what the vacuum tube was to the silicon chip.
But, it is superficial to diet to postpone your "demise." It's a quality of life issue: corn vs. insulin resistance, coffee vs. arthritis, flour vs. allergy symptoms, sweets vs. digestive tract diseases, hydrogenated fats vs. bad cholesterol.
Everyone can do their own cost/benefit analysis. What we tell ourselves is "living life" may merely satisfying a gnawing addiction. There's a lot of tasty foods out there that didn't arrive until relatively recently in human history, and not everyone's system is optimized to digest and assimulate them properly.
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