Just host a dinner party (I dare you), and you’ll realize how fractured American dietary preferences have become. You’ll likely be bombarded with news of your guests’ gluten-free, dairy-free, or vegan lifestyles. Some may have gone paleo or decided to quit sugar.
Such “food tribes” are nothing new. “Humans have a seemingly innate desire to belong, and food preferences have always been one way to do that,” notes Marion Nestle, PhD, a nutrition professor at New York University. What is new, say dietitians, is just how many people are restricting their diets—not as a fleeting weight loss tactic, but as a way of life.
According to market-research firm NPD Group, one in three U.S. adults minimizes or eliminates gluten intake. Five percent of Americans eat vegetarian by eschewing meat, fish, seafood, and poultry, and 2.5 percent are strictly vegan (no animal products, including eggs and dairy), according to a Harris Poll commissioned by The Vegetarian Resource Group. On the flip side, the carnivorous paleo diet topped the list of most Googled diets in 2013, converting an estimated 1 million to 3 million Americans, according to research by The State University of New York (SUNY).
Experts in each tribe point to studies suggesting these eating plans may reduce risk of chronic diseases like diabetes and heart disease plus gastrointestinal problems and argue that because they emphasize whole foods—an undeniable plus—they beat typical American fare.
But the tribes are not above criticism. Judy McLean, PhD, a nutrition professor at University of British Columbia, says there’s “so much restriction going on” that she’s seeing vitamin deficiencies she hasn’t tracked in years. “Avoid dairy and wheat and you cut out a lot of fortified foods,” she says. Adds Nestle: “One of the classic tenets of adequate nutrition is variety in food intake. So eliminating entire food groups means you have to be very careful to replace missing nutrients.”
What’s the rationale behind America’s top food tribes? Do they really make people healthier? Are they here to stay? Here’s a look.
1. Gluten free
The gist: Gluten is a protein composite naturally present in wheat, barley, and rye; it’s also added to baked goods to make them chewy and used to thicken sauces, soups, condiments, and other processed foods. According to the Archives of Internal Medicine, 1 in 133 people has celiac disease (CD), a genetic autoimmune disorder in which exposure to even trace amounts of gluten prompts antibodies to attack the intestinal wall, damaging the hairlike villi critical for nutrient absorption.
If you have this diagnosis, definitively confirmed via small-intestine biopsy, “you should be 100 percent gluten-free all the time,” says Jessica Crandall, RDN, a spokesperson for the Academy of Nutrition and Dietetics.
At least another 6 percent of the U.S. population suffer from nonceliac gluten sensitivity, a distinct condition that can lead to a vast array of symptoms, including diarrhea, bloating, cramping, neurological problems, and joint pain. (Some estimate as many as one in four people suffers from some physical aversion to gluten.)
Because of its chemical structure, studies show, gluten resists being broken down by gastric enzymes. “No human can fully digest gluten, so you have this undigested protein hanging around in your digestive tract,” says Doni Wilson, ND, a New York–based naturopath. “Some people’s bodies don’t pay attention to it. But for others the immune system spots it and attacks.” Research shows gluten can also open up the spaces between cells in the GI tract, sometimes called “tight junctions,” creating permeability and possibly leading to “leaky gut” syndrome.
Pros and cons: One-fourth of those eating gluten free do it for weight loss, but there
is little scientific evidence that it helps, says Crandall. In fact, for those with CD, a gluten-free diet heals the gut and boosts nutrient absorption, often leading to weight gain. Gluten-free “junk foods” augmented with fat for taste can pack on pounds.
That said, people who go off gluten, whether they have CD or not, tend to lower their intake of all refined carbohydrates, which can trim pounds in the short run. Some studies show eschewing gluten can quell irritable bowel syndrome, fibromyalgia, rheumatoid arthritis, and psoriasis. Research on the diet’s impact on insulin is mixed.
Bottom line: Unlike the standard blood test or biopsy used to diagnose CD, there is no gold-standard test for nonceliac gluten sensitivity, but some physicians use stool and blood tests to look for antigliadin IGA and IGG that hint at it. Test or no test, says Wilson, “everyone should be conscious of how much gluten they are eating and try to at least reduce it. It has found its way into so many foods that if you are not aware of it, you could be eating gluten all day long.” If you go cold turkey, just be sure you’re supplementing with B vitamins, iron, folate, and fiber, often present in grains and breads.
The gist: “We didn’t create this diet. We just uncovered the way humans always ate,” says Loren Cordain, PhD, professor emeritus at Colorado State University whose 2002 book The Paleo Diet helped launch the paleo movement. Emphasizing foods that “mimic the food groups of preagricultural, hunter-gatherer ancestors,” it pushes protein (25 percent to 35 percent of daily intake versus the typical 15 percent), fewer carbs (35 percent to 45 percent, derived strictly via nonstarchy fruits and vegetables), and moderate to high intake of healthy fats. Paleo favors grass-fed meats, nuts, greens, and seeds, while forbidding dairy, grains, legumes, refined sugars, and salt.
“Seventy percent of calories in the typical U.S. diet come from refined sugars, grains, vegetable oils, and dairy. Paleo reduces our reliance on those,” says Cordain, pointing out that “no other mammal consumes dairy past the weaning period.” Cordain also lists a host of conditions, including acne, that are aggravated by milk. Grains, he says, are inedible except when cooked, and from an evolutionary standpoint humans only recently began cooking food.
Pros and cons: At least 16 human studies indicate that the paleo diet has favorable short-term results on conditions like multiple sclerosis, diabetes, and heart disease. One survey by SUNY historian Hamilton Stapell found that 31 percent of paleo eaters do it to lose weight, and endorsements from celebrities like slimmed-down NBA star LeBron James are likely to draw more devotees.
But “my number-one concern is long-term compliance; it is so restrictive,” Crandall says. Many paleo dieters complain of constipation after taking out fibrous grains and adding more meat, and if they’re not careful, they can end up eating too much saturated fat, which some dietitians still contend is hard on the heart, and too few carbs, causing fatigue.
The bottom line: Done carefully, paleo is essentially a clean, low-carb diet, which can be beneficial, particularly to people with dairy and gluten sensitivities, says Wilson. But will paleo grow? Cordain says yes. Stapell seriously doubts it, noting that in a recent survey of paleo dieters, 74 percent hold a bachelor’s degree or higher, nearly half make more than six figures, and 92 percent are white—a small, elite minority. “It will remain a fringe movement with a small but highly dedicated group of followers,” he says.
The gist: Unlike other food tribes that hinge on health benefits, vegetarianism and veganism often start with an ethical decision. “The serious vegans are generally doing it for animal rights and environmental reasons. Better health is just a nice perk,” says Jeff Kaufman, a longtime vegan and founder of Roots Market and Great Sage vegan restaurant in Clarksville, Maryland. Nutritionists like Crandall say the strict vegan movement isn’t growing significantly. Rather, more people are dabbling in a “plant-based” diet; one in three Americans is trying to eat vegetarian or vegan a “significant” amount of the time.
Pros and cons: In July 2014, Kim Williams, MD, president of the American College
of Cardiology, made waves by writing on MedPageToday.com about his long-
standing vegan diet and his advice that patients with heart disease or diabetes risk adopt it. One 2014 systematic review and meta-analysis of clinical trials involving 21,604 people showed vegetarians have significantly lower blood pressure than meat-eaters. Another looked at 34,192 Seventh-day Adventists (who advocate vegetarianism) and found males’ lifetime risk of heart disease was 37 percent lower than that of meat-eaters. A subsequent study looking at 73,308 Seventh-day Adventists found they were significantly less likely to die prematurely. A 2006 clinical trial looked at 99 people with type 2 diabetes; half went on a vegan diet and half ate a diet recommended by the American Diabetes Association. After 22 weeks, 43 percent of the vegan group were able to reduce their diabetes medication, compared with 26 percent of the ADA group.
Williams himself cut out animal products upon learning he had high LDL cholesterol. Within six weeks, his LDL decreased from 170 to 90. But he cautions that more research is needed. “American Heart Association guidelines do not specifically recommend a vegan diet because so far the studies are very large and observational, or small and randomized,” he says.
The bottom line: Although a plant-based diet appears to benefit people at risk of heart disease and diabetes, it can be challenging to get enough protein, iron, and B12 (all abundant in meat) and DHA-EPA omega-3 fatty acids (found in fatty fish). “If people are just living on pasta and bagels, they are going to end up with a very high-carb diet and miss out on the nutrients that come from animal sources,” says Wilson. The good news: As vegan and vegetarian offerings become more tasty and accessible, it’s getting easier to join the tribe.
No look at food tribes would be complete without a glance at the burgeoning personalized-nutrition or “biohacking” movement, in which people use cutting-edge health technologies to gauge precisely what’s going on inside their bodies and adjust their eating habits accordingly.
For example: You can send a blood sample to web-based WellnessFX to test for things like anemia, thyroid dysfunction, or nutrient deficiencies, and then access its computer algorithm and an online physician consultation to choose specific foods and dietary supplements for your needs—or even to fend off illnesses to which you may be predisposed. Genetic testing company Pathway Genomics uses DNA testing to guide you, via your practitioner, to the ideal way of eating for optimal health.
UBiome enables you to send in a stool sample and find out precisely what bacteria types reside in your gut, what you are missing, and how to gain a better balance via food. Affordable, do-it-yourself gadgets like Fitbit and Jawbone let you track things like calories (in and out) and heart rate, in real time. One in ten American adults owns an activity tracker, according to a recent survey by market-research firm Endeavour Partners.
Many naturopathic physicians test for conditions such as allergic reactions, adrenal stress, and intestinal permeability to guide dietary decisions. “People say, ‘I am only going to follow gluten free or low carb or paleo,’” says Doni Wilson, ND, who believes that any of these diets can work great for the right person. “Really, the key is to look at a person’s genetics, blood, symptoms, and personal preferences and integrate all of that to determine what works best for their unique body.”