|
Though food is supposed to be one of life's simple pleasures, few things cause more angst and confusion. It's no wonder why. We're constantly being told which foods we should eat to be healthy, which diets we should follow to be skinny, which preparation methods we should use to be safe, and which chemicals and contaminants in food we should shun to avoid illness. It's enough to give anyone indigestion. If you're confused about what to believe, you've come to the right place. In "Coffee Is Good for You," I'll give you the bottom line on an array of popular diet and nutrition claims in a quick, easily digestible way. Research about diet and health rarely yields the equivalent of DNA evidence, which provides incontrovertible proof. All types of studies come with caveats. However, if interpreted properly, a body of research can allow us to make sound judgments about how believable a claim is. To that end, I've carefully reviewed the relevant studies and assigned each claim to a category on what I call the Truth Scale:
Let's start by looking at three common sweeteners. High-Fructose Corn Syrup is Worse for You Than Sugar: Weak Evidence Whatever you think of high-fructose corn syrup (HFCS), you have to feel at least a little sympathy for the hapless souls assigned the task of boosting the sweetener's rotten image. When they conducted a $30 million advertising campaign intended to allay fears about the product's safety, the main result was a slew of parodies that mercilessly mocked the ads' message. For example, in one real commercial, a woman questions a fellow mom for serving kids an HFCS- sweetened beverage. Confidently explaining that the product is "natural" and "fine in moderation," the HFCS user puts the accuser in her place and leaves her speechless. A series of YouTube spoofs shows two women engaged in a virtually identical conversation, except that the woman being questioned (played by a guy in drag) is defending lead-containing products from China, female genital mutilation, and KKK cross burnings. You definitely have a PR problem when your product is likened to such things. Food manufacturers, which use HFCS in everything from cereals to soda, like the sweetener because it's cheaper than sugar and prolongs the shelf life of products. But many people regard it as a sinister chemical concoction that's causing obesity along with diabetes, heart disease, and other conditions. Indeed, lab experiments have found that rodents fed HFCS gained more weight than those receiving table sugar. The rats also showed signs of so-called metabolic syndrome—a combination of several risk factors, such as belly fat and increased blood pressure— which has been linked to heart disease and diabetes. But there's little evidence from human studies that HFCS is any worse for our waistlines or our health than table sugar (also known as sucrose). The fact that HFCS and table sugar have a very similar chemical makeup also casts doubt on the claims. Both contain the sugars fructose (the type in fruit) and glucose in roughly equal proportions. Moreover, HFCS has the same number of calories as table sugar. One difference is that the fructose and glucose are chemically bonded in table sugar but not in HFCS. Some argue that as a result, our bodies metabolize table sugar and HFCS differently. At this point, however, it's just a theory with no hard proof. We do have evidence that the body processes pure fructose differently than glucose. Broken down in the liver, fructose is more likely than glucose to result in the production of harmful fats. There are also hints that large amounts of fructose may make the body resistant to insulin. Whether the cumulative amount we get from HFCS actually causes harm is unknown. The fact that HFCS is processed (and not "natural," as those industry ads have claimed) doesn't necessarily render it a health risk, as some maintain. But even though the science to date hasn't proven HFCS to be uniquely villainous, the product isn't totally benign either. Like table sugar, it's a source of empty calories, and consuming too much sugar— in whatever form— can lead to obesity and related health problems. In another effort to improve their product's image, the producers of HFCS are pushing to officially rename it "corn sugar." Getting a new identity has certainly worked for other foods, including canola oil (formerly rapeseed oil) and orange roughy (slimehead). I just wish Chinese restaurants could find a more appetizing name for the poo- poo platter. Honey is More Healthful Than Sugar: Weak Evidence If you've ever wondered what a cross between a lobster and a blowfish looks like, you can find out by seeing me when I get stung by bees. It's not pretty. As a result, I try to stay as far away from them as I can. But a growing number of people apparently don't feel a similar need. Backyard beekeeping is booming, thanks in part to the grow-your-own-food movement. More people are drawn to the idea of producing their own honey, which according to one blogger, "has long been considered healthier than sugar." At least that's the buzz. But the truth isn't quite so sweet for honey. Honey is composed mainly of fructose and glucose, the same ingredients in table sugar (also known as sucrose). Some claim that our bodies respond more favorably to honey than to sugar, but there's little solid evidence for this. On the glycemic index, which is a measure of how foods affect blood sugar levels, some types of honey cause less of a spike than sucrose, but generally both score about the same. Honey has come out ahead of sucrose in a few short- term studies comparing their effects on blood sugar, insulin levels, and cholesterol. However, the studies are too small and preliminary to tell whether these advantages are real or whether they translate into any lasting impact on people's health. Another frequently cited advantage of honey is its higher levels of nutrients. Indeed, it does contain a number of vitamins and minerals not found in table sugar, including calcium, potassium, zinc, vitamin C, and niacin. However, the amounts are minuscule. To meet your daily requirement of calcium, for example, you would need 1,000 tablespoons of honey. While antioxidant levels in honey vary depending on the plant source of the bees' nectar, one study found that overall, the antioxidant content of honey is higher than that of white sugar but lower than that of brown sugar. Whether these differences affect our risk of heart disease, cancer, or other conditions is unknown. As for calories, honey actually has more than sugar— 64 vs. 49 per tablespoon. But because honey is sweeter, you may need to use less. Some people choose honey over sugar because they believe honey is less processed. In fact, typical store brands are processed with heat and filtration to remove wax, pollen, and other impurities. The alternative is raw honey, which enthusiasts swear is more healthful than processed honey. But here too the evidence is skimpy. On a less sour note, honey isn't any worse for you than table sugar, and it can be a great addition to many foods and beverages. Just watch your intake as you would with sugar. If you want to become a beekeeper and produce your own honey, more power to you. All I ask is that you keep your bees far from me. Aspartame is Unsafe: Weak Evidence For journalists, press releases are a little like reality TV shows: They're totally unavoidable, mostly forgettable, and occasionally entertaining. One of my favorite releases came in 1998 during the Bill Clinton– Monica Lewinsky scandal. Titled "The Deposition of President Clinton," it pointed out that when the former president underwent grand jury questioning about his relationship with Lewinsky, he repeatedly responded with answers like "My memory is not clear" and "I don't remember." The release's author, a physician, noted that the president was drinking Diet Coke during the deposition. His conclusion: Aspartame (aka Equal and NutraSweet), the artificial sweetener in the beverage, was the cause of Clinton's apparent memory lapses. Never mind that President Clinton's memory is otherwise extraordinary. The doctor, it turns out, is a longtime anti- aspartame crusader who was seeking to exploit the scandal for his cause. If nothing else, he deserves credit for knowing how to get attention—or at least a good laugh. On the Internet you can find plenty of others who rail against aspartame for causing not only memory loss and Alzheimer's disease but also brain tumors, multiple sclerosis, depression, chronic fatigue syndrome, and birth defects, among other maladies. But decades of research have turned up little hard evidence for such assertions. Though Italian researchers have found elevated rates of lymphoma, leukemia, and other cancers in rodents ingesting aspartame, most other animal studies have shown no connection between aspartame and cancer. More important, in a cohort study involving nearly 500,000 people, there was no increased risk of blood or brain cancers among aspartame users. Likewise, most studies looking at neurological and behavioral issues haven't found adverse effects from aspartame. When a panel of scientists reviewed more than 500 studies, they uncovered no major safety problems. The review was funded by a Japanese manufacturer of aspartame, but the experts were unaware of who the funder was, and the company had no role in selecting the experts. The panel's conclusions echo those of both the FDA and the European Commission's Scientific Committee on Food, which say that a daily intake of up to 40 or 50 milligrams of aspartame per kilogram of body weight is safe for most people. Translated into plain English, this means a 150- pound adult can safely consume up to about 19 cans of diet soda a day. (Not that anyone says drinking this much is advisable.) Obviously, most of us fall well below that threshold. Still, aspartame may adversely affect certain people. One of the most common complaints is headaches, an effect detected by some (but not all) research. Also, people with a rare inherited condition called phenylketonuria (PKU) can't metabolize phenylalanine, an amino acid in aspartame. To avoid an unsafe buildup, they need to steer clear of the sweetener. (Hence that cryptic warning "Phenylketonurics: Contains Phenylalanine" on the labels of foods and beverages that contain aspartame.) Despite the claims of some aspartame opponents, there's no solid proof that phenylalanine from normal amounts of aspartame poses a danger to the rest of us. The same goes for methanol, which is also produced when our bodies break down aspartame. In fact, we get more methanol from fruit juice than from aspartame. Those who are convinced aspartame is poison or an evil plot may denounce me as an ignoramus or a pawn of industry for not agreeing with them. But at least they won't be able to blame my "confusion" on aspartame-related brain problems. Personally, I can't stand the taste. .jpg) Adapted with permission from "Coffee is Good for You" by Robert J. Davis, PhD, by arrangement with Perigee, a member of Penguin Group (USA) Inc., Copyright (c) 2012 by Robert J. Davis, PhD, MPH.
|
