Products labeled “organic” are not permitted to include ingredients that contain genetically modified organisms. (Ty Wright/Bloomberg News)

Gluten-free. Non-GMO. No high fructose corn syrup. These days, it can feel as if you need a PhD in nutrition to navigate the supermarket. And those terms don’t necessarily mean that the food is actually good for you. Here’s how to decipher some of the most common claims:

If the label says “gluten-free,” that doesn’t make a product healthier. Almost 40 percent of people think that gluten-free foods are helpful for everyone, not just those with celiac disease or a gluten intolerance. But that’s an erroneous assumption.

Because gluten — a protein found in wheat, barley and rye — adds texture to foods, manufacturers often load up gluten-free products with extra sugar and fat to compensate, says Dawn Jackson Blatner, a dietitian in Chicago. In addition, many gluten-free products are made with rice flour, which Consumer Reports’ tests found may contain worrisome levels of arsenic.

Consumer Reports’ advice: Unless you have celiac disease or another diagnosed gluten intolerance, consider skipping the gluten-free aisle entirely.

If the label says “Non-GMO Project Verified,” you can trust it. Ninety-two percent of consumers think that foods containing genetically modified organisms (GMOs) should be labeled, according to a recent randomized survey of 1,000 adults by the Consumer Reports National Research Center, and 40 percent look for non-GMO labels when they shop.

Almost 40 percent of people incorrectly assume that gluten-free foods are helpful for everyone. (Jon Elswick/AP)

The Food and Drug Administration doesn’t require the use of GMOs to be disclosed on food packaging. But concerns about the potential health and environmental risks recently led Vermont to pass a law requiring mandatory labeling.

Consumer Reports’ advice: Our tests of products made with corn or soy — the major genetically modified crops — found that most non-GMO claims on food packaging are reliable, especially “Non-GMO Project Verified.” That’s the label for a certification process that tests ingredients for the presence of GMOs and is verified by third-party certifiers. GMO ingredients are not permitted in organic products. But if a corn or soy product is just labeled “natural” or there’s no reference to GMOs, it probably has GMO ingredients.

If the label says, “No antibiotics/organic,” that’s a plus. About 80 percent of antibiotics sold in the United States are used in farm animals, mostly to prevent the animals from getting sick because of the conditions in which they’re raised. The overuse of those drugs is a major cause of antibiotic resistance, which makes the drugs no longer effective against certain bacteria. That can make infections more difficult to treat.

Consumer Reports’ advice: There are many claims about antibiotic use, but not all of them are meaningful. The “USDA Organic” label is one of the best guarantees that the animal didn’t receive antibiotics. With poultry, however, birds can be given antibiotic injections while they’re in eggs or during their first day of life and still carry the “organic” label. So look for a “no antibiotic” claim alongside “organic.”

Any claim about antibiotic use accompanied by a “USDA Process Verified” label is reliable. “Animal Welfare Approved” is another good label. It means that the animal was raised in a healthy way, and healthy animals aren’t given antibiotics. “Antibiotic free” and “no antibiotic residues” are unapproved claims, and you can’t count on them. “Natural” is also misleading. On meat, it means that the product was minimally processed and has no coloring or artificial ingredients, not whether the animal was given antibiotics.

If the label says “No trans fat,” the product isn’t necessarily good for you. Last fall, the FDA made a preliminary determination that partially hydrogenated oils (PHOs), the main source of trans fat, are no longer generally recognized as safe. If that finding is finalized, companies will no longer be able to sell products with PHOs in them without FDA approval.

That’s not the case yet, though. A recent analysis of more than 4,000 packaged-food products by the New York Department of Health and Mental Hygiene found that 9 percent contained PHOs and that 84 percent of those foods listed zero grams of trans fat on the label. Keep in mind, too, that products that don’t contain PHOs aren’t necessarily better for you. Some use so-called “healthy” saturated fats such as palm oil, palm kernel oil or coconut oil, which can be just as bad for your heart, if not worse.

Consumer Reports’ advice: Look at the ingredients list to make sure there are no PHOs. A product containing less than 0.5 grams of trans fat can still be labeled trans-fat-free. Second, keep an eye on saturated fat; the American Heart Association (AHA) recommends no more than 6 percent of your daily calories (about 13 grams for 2,000 calories) come from saturated fat each day. And last, look for products made with canola or olive oil instead of palm or palm kernel oil.

If the label says “No high fructose corn syrup,” that doesn’t mean “no added sugar.” Tossing high fructose corn syrup off an ingredients list has more to do with marketing than with science. Similar to sugar chemically, it’s often used because it’s cheaper and helps maintain color, texture and flavor. But it has roughly the same calories as sugar and similar health risks, notes Walter Willett, chair of the department of nutrition at the Harvard School of Public Health.

Consumer Reports’ advice: Nutrition Facts labels list the grams in a serving, but they don’t distinguish between added sugars and the sugars naturally present in milk, fruit and vegetables. When reading the labels, be on the lookout for other forms of added sugars, such as agave nectar, brown sugar, corn sweetener, dextrose, evaporated cane juice, fructose, fruit-juice concentrate, honey, maltose, malt syrup, maple syrup, sucrose and syrup.

Correction: In Tuesday’s Health & Science section, the Consumer Reports Insights column indicated that “no antibiotic growth promotants” is an unapproved claim that is made for some food products. In fact, one arm of the USDA recently began approving such claims. This is version has been corrected.

Copyright 2014. Consumers Union of United States Inc.

For further guidance, go to www.ConsumerReports.org/Health, where more detailed information, including CR’s ratings of prescription drugs, treatments, hospitals and healthy-living products, is available to subscribers.