“I never know what to believe when I hear nutrition news!”
“Nutrition advice is so confusing…and it changes every week!”
“It seems like even the experts disagree.”
I wish I could get through one day, even an hour, without uttering one of these phrases. The amount of conflicting and baseless nutrition advice I encounter takes my breath away. And I don’t even watch Dr. Oz!
And I’ll bet I’m not alone!
Until a few years ago, I could count on certain media sources—a couple of US newspapers, one or two websites, most science journals—to report nothing but the truth when it came to nutrition, even when that meant saying, which they often did, “We don’t know the answer…The evidence isn’t strong enough…” Now, I can honestly say that no newspaper, medical journal, health website, television show, celebrity, or food label is completely blameless…or credible. The mainstream media relies on jaw dropping headlines to suck you in, whether it’s online clickbait or hardcopy magazines, newspapers, and books. And the claims on food labels (like “natural” or “cholesterol-free”), which we assume are designed to help us make good shopping decisions, are often nutritionally meaningless and are really just designed to get the items into our shopping carts.
Is it possible for the average person to hear or read about a nutrition study or nutrition advice and truly evaluate its credibility? I’d like to share some steps you can take to become a savvier consumer of nutrition news, advice, and food! In this blog, I’ll talk about deciphering nutrition advice and news reports. In a subsequent blog, I’ll talk about how to decipher food labels.
- Nutrition advice based on what?
“I tried this new fried spider diet, and it’s made me feel like a new person,” says your Aunt Tessie. Are you already on your way to Spiders ‘R Us to pick up dinner? So much of the time, we hear someone telling us we need to try eating a different food, eating it in a different way (like raw), or taking a new supplement, but what research is the advice based on, and what are the credentials of the person who is telling you about it? Unless your Aunt Tessie, your fitness trainer, your chiropractor, even your doctor or dentist has extensively studied nutrition (and trust me, they almost never have, regardless of what they say), their nutrition credentials and intuition are probably no better than yours. And if the person is trying to sell you a product, flee without even saying goodbye (that’s what my husband and I did with our last chiropractor—the one who urged me to attend his class to “really learn about nutrition!”)!
Who should you believe? Beside me, of course?!? Your health care provider or a credentialed nutrition professional, provided the person has talked to you carefully about your family history and assessed your lifestyle before offering you advice and, most importantly, doesn’t try to sell you on a product or diet you must adopt. What about the advice in those waiting room magazines, on Oprah, or on WebMD TV? Read on.
- Nutrition news? When you hear or read a news report about the results of a nutrition study, consider the following:
- Were the study subjects laboratory animals, like rats, mice, primates, pigs, dogs, or cats? If they were, the study’s findings may be intriguing but of extremely limited practical application to your situation. Don’t let anyone scare you into thinking that the way a food affects rats is the way it will affect you! We’re not rats (well, maybe those doctors trying to upsell you expensive supplements are)! Also check to see if the human study participants were people who were suffering from a particular disease you don’t have, or people from a very different ethnic group, culture, nation, age group, or even gender. If so, their response to a particular food or diet might not be any more applicable to you than to a tortoise.
- It’s critical to ensure the study was of the highest quality, namely a double-blind randomized placebo-controlled trial. Randomized means that the researchers actually randomly divided people into groups and assigned one group to a particular diet and the other—control–group to a different diet, preferably one that is more similar to what we usually eat. It’s also imperative that the two diets be as identical as possible with the exception of the one nutrient or food that is being studied. If the point of the study is to determine the effects of a supplement, the control group should receive a placebo that is indistinguishable from the supplement. Double blind means that the study participants–and the researchers themselves–are “blinded” to the details of their diet, to the extent possible. In other words, the study participants should not be told or be able to guess the diet group to which they’ve been assigned. If they have been told (or can guess by the taste of the food or pill), they might be more likely to try to please the researchers by reporting that the special diet or supplement had the desired effect or that the control or placebo diet had no effect. Some–poorly designed–studies don’t even bother with a control group, a big red flag.Another red flag to watch out for is a study that, instead of actually assigning people to a special diet or food or supplement, asked a large group of people what they ate during a certain time period or tended to eat (sometime decades earlier) and then periodically asks them whether they developed a particular disease or any diseases. Unfortunately, many nutrition studies, the majority sadly enough, are done in just this way, and much nutrition advice and policy is based on just such studies. Do you remember what you ate when you were 15? I can’t remember what I ate for dinner two nights ago! Another problematic kind of study is one that asks a bunch of people with a disease what they ate or didn’t eat as children, teens, or younger adults. The results of all such studies, called cohort or observational studies, are never an adequate basis for giving nutrition advice to individuals or setting nutrition policy that will affect millions of people. Why are these kinds of studies so popular among researchers? Because randomized controlled trials are really hard (sometimes impossible) and expensive to do, even though these are the ones you should believe! Read on!
- Make sure to count how many people were in the study. It may seem silly, but the more people, the more credible the findings. A study that randomly divides 10, 20, or even 30 people is unlikely to produce meaningful results because a finding in a very small number of people could be just a chance finding and also because most nutrition interventions cannot be expected to have really massive effects.
- Look for studies that were long in duration. Nutrition intervention trials are usually fairly short-lived, often too short to be able to see the hoped-for effects. What’s more, if the study intervention is difficult to stick with (imagine eating a salt-free diet!), few participants are likely to remain compliant with the instructions.
- Did the scientists who conducted the study consider other possible explanations for their results? Nutrition studies in people are extremely challenging because scientists can seldom completely control what people eat, and most people (including trained nutritionists) can seldom recall accurately what they ate. It’s also a fact of life that numerous factors besides nutrition can also move the needle, that is, affect the outcomes the scientists are hoping to modify with food.
Are you still ready to believe the findings of that study you heard about on the news?
- Well-researched nutritional hysteria? Part of my job consists of reviewing the results of every study that was ever done (published or not) to answer certain questions (like, does reducing dietary salt decrease your chances of developing heart disease?). Every single aspect of the methods we use to do these kinds of reviews must be described transparently: in such minute detail that anyone could reproduce the review exactly and get the same results. Anyone who believes we have biased our findings by omitting studies we should have included, including studies we should have omitted, or doing an incorrect analysis can contest our findings and demand we repeat them. This kind of research is painstaking, time-consuming, costly, and requires a multidisciplinary team of information specialists, subject matter experts, reviewers, statisticians, programmers, communicators… Unfortunately, a different–“instant”–type of nutrition reporting has become popular among journalists fascinated with nutrition. This reporting appears to be exhaustive and objective, sometimes even resulting in full-length books, but in fact it uses cherry-picked sources, usually to support wild claims. What should you do to evaluate those nutrition books on the best-seller list or the opinion pieces in the Health section of your daily newspaper or all that clickbait on the web?
- Don’t buy into nutrition writing that vilifies—or worships—certain foods or food groups.
- Don’t believe your health and survival depend on giving up carbs, sugar, saturated fat, beans, corn, dairy products, dark green vegetables, agricultural products, foods that contain GMOs (trust me, all foods are the products of eons of breeding and genetic manipulation, mostly haphazard; genetic engineering has precision on its side – but that’s for another blog!), foods that are not organic, or foods that contain gluten (unless you’ve been tested for and diagnosed with celiac disease).
- Likewise, don’t believe that any ancient grain, berry, herb, spice, sweetener, alkaline water, or detox juice cleanse is a miracle food. That also goes for apple cider vinegar, coconut (oil, milk, or sugar), avocado, salmon, and kale (it makes me wonder how much money Dr. Oz has made for endorsing green coffee bean extract and raspberry ketone extract, among other things). Fruits, vegetables, nuts, whole grains, and beans are the closest things we have to miracle foods. And fish, lean meats, and dairy foods (yes, dairy) can contribute strongly to a healthy diet. These are all fine foods, but no one by itself is a miracle food. You can’t live on it and it won’t erase the donuts you ate for breakfast or the 6-pack of beer you consumed this weekend!Now that you know what to look for in seemingly well-intentioned nutrition advice, news stories on the latest nutrition study, and apparently exhaustive analyses of some body of nutrition research, you need to understand the complexities of food labels – but that’s for next week. See you then!!!!