With nutritional research, it’s often hard to know what you can believe. The latest study makes headlines, often when the research is far from definitive, then the opposite is asserted a few years later.
In general, claims that are supported by multiple high-quality studies—preferably, randomized trials involving thousands of participants—are more likely to be true than those derived from a single (and sometimes industry-funded) source.
What’s believable and what’s not…*
Claim #1: Red wine is more healthful than other forms of alcohol.
Limited evidence. Twenty years ago, it was widely reported that red wine protected the saturated fat–loving French from heart disease. Red wine may have health benefits, but research as a whole suggests it’s no better than white wine, beer or other alcoholic beverages.
You may have heard about resveratrol, an antioxidant that’s present in red wine. It’s possible that resveratrol helps prevent heart disease, but this hasn’t been proven in long-term studies with humans. Researchers suspect that alcohol itself—not individual components in wine—is the protective factor.
All alcoholic beverages increase HDL, the protective (“good”) form of cholesterol. Alcohol also reduces clotting, a cause of heart attacks. People who drink moderately (no more than two daily drinks for men or one for women) generally have less heart disease than nondrinkers.
Claim #2: Coffee is good for you.
Good evidence. Despite what you’ve heard, coffee doesn’t damage the heart or increase risk for cancer. In fact, moderate coffee drinkers are less likely to suffer from heart disease, diabetes, stroke and some cancers, such as colorectal and malignancies of the liver, than those who don’t drink it. In general, decaffeinated coffee offers the same health benefits.
Caution: A cup of regular or decaf coffee without milk and/or sugar has only a few calories, but some of the “coffee beverages” at Starbucks and other restaurants can have 200 to 400 calories per serving. If you’re watching your weight, you might want to drink your coffee black.
Claim #3: Bottled water is safer than tap water.
Limited evidence. You might appreciate the taste and convenience of bottled water, but it’s not necessarily more healthful than what comes from a tap in most areas of the US. In fact, there’s a good chance that the bottled water you’re drinking did come from a tap.
American tap water is regulated by the Environmental Protection Agency. It undergoes frequent testing to ensure that it does not contain harmful levels of chemicals, bacteria or other contaminants. Bottled water is regulated by the Food and Drug Administration, which has less stringent standards.
Surprisingly, bottled water is required to be tested only annually, while municipal tap water is sometimes tested several times a day. If you have old pipes in your home, you may want to ask your municipality to test the water for impurities.
Even though bottled-water companies often market their products with images of glaciers or mountain springs, it’s usually just tap water that’s been filtered to make the water taste or smell better. However, there are some bottled waters that actually come from natural springs. Note: The chemical Bisphenol A (BPA) is not a potential health concern when drinking most brands of bottled water—most bottlers use safer plastics.
Claim #4: Well-done meat increases cancer risk.
Good evidence. Meat (red, pork, poultry and, to a lesser extent, fish) that’s well-done and/or cooked at high temperatures—during grilling, panfrying and broiling, for example—produces heterocyclic amines (HCAs), chemical compounds that have been linked to a variety of cancers, including breast, prostate and stomach cancers.
The dangers are dose-related—the more well-done meat you eat, the higher your cancer risk. But even small servings of meat can increase the risk. One study, for example, found that men who averaged as little as one-third of an ounce of well-done meat daily had a 42% increased risk for prostate cancer. Lengthy cooking times and high-heat cooking methods produce the most HCAs. Helpful: Marinate meat in a mixture (containing olive oil, for example) of antioxidant herbs, such as rosemary, thyme and garlic, before cooking to reduce levels of HCAs. Also, precooking meat in the microwave shortens cooking time.
Claim #5: Olive oil is superior to other oils.
Limited evidence. Olive oil, used in the Mediterranean diet, is high in monounsaturated fat. For years, researchers have linked this type of fat to cardiovascular benefits.
However, one large study, which compiled data from other studies, found that participants who replaced saturated fat in their diets with polyunsaturated fat (as found in safflower and corn oil, for example) were less likely to suffer heart attacks, but that wasn’t the case for those who consumed monounsaturated fat instead of saturated fat.
This doesn’t mean that olive oil isn’t a healthful choice. Both polyunsaturated and monounsaturated fats lower LDL cholesterol and raise protective HDL cholesterol. Both types of fats (and oils) are beneficial—and they’re clearly superior to the saturated fat in meats and many processed foods.
Claim #6: Sea salt is more healthful than other salts.
Limited evidence. Salt is salt. Both sea salt and table salt consist mainly of sodium and chloride. The only difference is that sea salt is produced by the evaporation of seawater, a process that leaves behind extra minerals, such as copper, magnesium and calcium.
Since the minerals are present only in trace amounts, there’s little nutritional advantage to using sea salt. The minerals do add flavor, which means that you might use less salt—helpful for lowering blood pressure. Cutting back on table salt would have the same effect. Most table salt is iodized, but the typical American gets enough iodine from other food sources. So use sea salt if you prefer the taste, but it won’t improve your health.
*Conclusions regarding the nutritional claims in this article are based on a comprehensive review of the literature (including the quality of the actual studies) and what the preponderance of evidence has found.
