Most peoples’ diets are low in fruits, vegetables, and whole grains: that’s something we know.
But did a bad diet kill 11 million people in 2017? That’s what the latest nutrition study to come out of The Lancet has concluded. In fact, this study states that a bad diet kills more people per year than smoking (which only killed 8 million last year).
Predictably, the news media took a lot of liberties with this information, inventing some crazy, fear-mongering headlines AS USUAL!
Some of the headlines include, ‘Unhealthy diet killing millions around the world: Lancet study’, ‘Bad diets killing millions around the world: Lancet study’, ‘Deadly diets: Which foods take the heaviest toll?’
Note: The actual study is called ‘Health effects of dietary risks in 195 countries, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017’, not, ‘your diet is killing you’.
Because this study was all over the place, let’s take a look at it, what it found, and its limitations. Thanks to my friend and colleague, Dr. Pamela Fergusson, for fact-checking this with me (she’s a research ninja AND a fabulous plant-based RD)
Looking at studies done between 1990 and 2017 in 195 countries, the authors chose 15 dietary factors that appear to be high-risk, and attempted to reconcile the number of people with chronic disease and the deaths attributable to each factor.
The factors are:
Diet low in fruits
Diet low in vegetables
Diet low in legumes
Diet low in whole grains
Diet low in nuts and seeds
Diet low in milk
Diet high in red meat
Diet high in processed meat
Diet high in SSB
Diet low in fiber
Diet low in calcium
Diet low in fish and omega-3 fatty acids
Diet low in polyunsaturated fatty acids
Diet high in trans fats
Diet high in sodium
I’m sort of curious how a diet low in milk is a risk factor for anything, but okay. Maybe it was in 1990.
The study found:
Consumption of the ‘healthy’ foods was overall low in all countries. This means that no country was eating optimal amounts of nuts and seeds, milk, whole grains, etc.
Consumption of the ‘unhealthy’ foods was too high. Meaning, everybody ate too much trans fat, sugar sweetened beverages, processed meat, red meat, and sodium.
“Non-optimal intake” of fruits, whole grains, and sodium alone accounted for more than 50% of deaths attributable to diet.
Researchers believe that eating an optimal diet – ie opposite of the risks listed above – could prevent 1 in 5 deaths worldwide.
A healthy food system extends far beyond what’s in your kitchen. It’s a lot more than just what we eat, it’s how we grow, process, and distribute food as well.
The good things:
For once, it’s not about cutting things out; this study emphasizes the fact that adding in whole grains, fruits, and vegetables may positively impact your health. Authors state that we’ve been recommending to people for years that they cut things from their diet, but this hasn’t worked; they just replace the things they cut out with other, similar foods. Snackwells, anyone?
When I see someone talking about ‘optimal’ amounts of foods, I raise an eyebrow. I checked, and the recommended consumption levels for the foods listed in the study appear to be legit. Fruit sits at 250 grams, which is about 2.5 pieces. Vegetables are 350 grams, which translates into around 5 standard 75 gram servings. The fiber recommendation is 24 grams, and sodium, a fairly liberal 3 grams (for people who don’t eat a ton of ultra-processed food, that is).
This study is the first of its kind to give us a picture of diet and disease trends over 27 years, worldwide, and it’s quite the eye-opener. As risk of death from communicable disease goes down, chronic disease deaths rise. And as diets become westernized, chronic disease deaths rise.
The weird things:
The milk thing. I just can’t get past that.
The bad things:
As with all nutrition studies, this one is based on mostly observational studies. The authors get reeeeeeeeeally specific about just how many people are killed each year by some of these factors, but is that really accurate?
Check out this statement directly from the study:
In 2017, more than half of diet-related deaths and two-thirds of diet-related DALYs (disability-adjusted life-years) were attributable to high intake of sodium (3 million [95% UI 1–5] deaths and 70 million [34–118] DALYs), low intake of whole grains (3 million [2–4] deaths and 82 million [59–109] DALYs), and low intake of fruits (2 million [1–4] deaths and 65 million [41–92] DALYs.
The deaths they’re describing may be linked to high sodium, low whole grains, or low fruits, but to say that they’re attributable’ is not a statement I believe that they can make with confidence. There’s just no way of knowing if diet was directly responsible in all of those instances. Despite the definitive language in this study, the authors were also very transparent about its limitations.
The studies this review was based on give merely a peek into peoples’ lives. Sure, if someone eats a diet high in sodium, they might die prematurely. But what else is going on in their life? How many of these deaths can be attributed not only to sodium intake, but to the combination of that with other things such as poverty, genetics, and lifestyle habits? How many of these countries have overall food system issues versus ‘they just buy Froot Loops versus lettuce at the grocery store’?
The authors seem to feel the same way, saying in the write-up that “deaths due to some dietary risk factors might not be mutually exclusive, which could result in overestimation of the burden of disease attributable to diet.”.
The authors admitted that sometimes, they had to estimate risk of death from information they didn’t have. Any time you have to estimate anything, it takes away from the accuracy of your conclusions. Unfortunately, estimating is the only way that most nutrition studies ever draw any conclusions, because it’s impossible to keep people (especially 195 countries-worth) in a lab for long enough to prove a causal relationship. Still, the evidence linking diet and disease is very persuasive, and this study only reinforces that.
The media. Oh boy. Seriously? This is yet another great lesson in the power of clickbait. “Premature death may be linked to certain factors in the diet” is very different from “A bad diet kills 11 million people per year”. Hyperbole isn’t helping anyone understand anything or to make changes to their diet.
In short:
Does diet kill this many people a year?
We don’t really know. What we do know is that eating habits appear to be related to chronic disease and death, and countries where individuals consume more fruits, vegetables, and whole grains enjoy less chronic disease and its associated mortality. Despite the crazy headlines in the media, none of this is really new.
We know that as countries become more developed, they appear to have more westernized eating habits and more chronic disease.
All in all, the study is telling us what we already know, except now it’s on a global scale. Are the exact number accurate? Maybe, maybe not. But the trends are interesting.
Instead of cutting foods out of your diet and seeing what happens, try adding more food types in. Specifically, whole grains, fruits, vegetables, nuts, and seeds. Be a pencil, not an eraser.
And hey: when you see scary headlines in the media, take a step back and read them with a grain of salt.