On Nutrition

Two weeks ago, I talked about how to make sense of the nutrition research you see in the media and online, especially when the headlines are sensational. This week, I’ll talk about what it means when there is no research — or very little — to support a health claim, and where personal experience fits in.

Often, when I hear a nutritional claim that sounds too good to be true, I take a quick dive into the published research. Sometimes I find a few preliminary studies — maybe rodent studies or cell studies — that are promising, but not ready for prime time. Other times, I find a few studies that conclude something like, “Nope, nothing of substance here.”

And sometimes, there’s no research at all — zip, zero, zilch.

This could mean a few things. It could mean that due to basic knowledge about human biology and the composition of a specific food or combination of foods, there is no reason to do research on whether, say, eating bananas cures eczema (I’m totally making that up). It’s biologically implausible. When you do learn there’s no research showing that bananas cure eczema, it doesn’t warrant a response of, “Well, that means that they might.”

If something’s potentially beneficial and biologically plausible, it will be studied.

What about personal experience? Let’s start with testimonials you might find on TV or the internet. Whether or not the claims come from someone you know, if there is no research to back it up — and by research, I mean studies published in reputable, peer-reviewed journals — then there are two important questions to ask:

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1. Could this be a placebo effect? In other words, your belief that eating a turnip will ease joint pain, even though eating the turnip actually did nothing. This is the type of confusion that a randomized control trial can weed out.

2. What else changed? When you start eating more of a certain food, you typically start eating less of other foods. So what actually caused any changes you observe in your health — the addition, or the subtraction?

It’s also important to beware of false dichotomies. For example, when I point out there is no research to support claims about the miracle healing powers of celery juice, and that most of those claims were totally made up by someone with no medical or scientific background, I often get the response, “So, what then? We should just all eat junk food?” That’s a false dichotomy — it assumes that you have two choices, celery juice or junk food. In truth, there are many foods that are better choices for nutrition and health than “junk food.”

Does this mean that personal experience has no value? Absolutely not. Your personal experience has tremendous value — for you. If you change something about how you eat, and you feel better, and it won’t cause nutrient deficiencies or other harm in the long run, that’s great. But it doesn’t mean your friend or co-worker might have the same experience. That’s why it’s a good idea to “try on” even evidence-based nutrition information for size. How does it feel to eat in a different way? Is this something you can see yourself incorporating into your daily life for years to come? Those questions can help you make sustainable changes that are right for you.