Dietary Solutions to the Climate Crisis

In this episode, we look at ways to change our diet for the good of the whole planet.

In our first story, the EAT-Lancet Commission lays out the best diet for human and planetary health.

“Scientists have a [clear] moral obligation to clearly warn humanity of any catastrophic threat and to ‘tell it like it is.’” In November 2019, more than 11,000 scientists from 150 countries clearly and unequivocally declared “that planet Earth is facing a climate emergency.” CO2 levels are rising; the glaciers are melting; Antarctica is melting. The oceans are getting hotter, more acidic. Sea levels are rising, and so are extreme weather events. And yes, fossil fuel use is going up, like air travel––but so is per capita meat consumption. In fact, one of the solutions they offer to help the climate crisis is “eating mostly plant-based foods while reducing the global consumption of animal products.”

And what makes designing a sustainable diet so easy is that the same advice—like eat less meat—is good for both personal health––like reducing the risk of our number #1 killer––as well as for planetary health. The least healthy foods also cause the worst environmental impact. The foods with the most nutrition just so happen to be the foods that cause the lowest greenhouse gas emissions; so, you get this win-win effect.

So, let’s put it all together. If we are “to redesign the global food system for human and planetary health”—which is to say human health and future human health—what would it look like? Enter the EAT-Lancet Commission, “the result of more than two years of collaboration between 37 experts from 16 countries,” suggesting a cut in total meat consumption down to like an ounce a day—that’s like the weight of a single chicken nugget—all the while dramatically increasing our intakes of legumes (which are beans, split peas, chickpeas, and lentils), nuts, fruits, and vegetables––because we’re not just in a climate crisis, but a health crisis. Unhealthy diets cause more death and disease than smoking, more than unsafe sex, and alcohol, drug, and tobacco use combined. But we can address both crises at the same time by “increasing [our] consumption of [whole plant] foods and substantially reducing our consumption of animal source foods.”

Eating such a diet could save the lives of more than 10 million people a year and may just help save the world. The Paris Agreement had set out a boundary condition, an aspirational goal for a carbon budget to help prevent catastrophic impacts, and “staying within the boundary for climate change can be achieved by consuming plant-based diets.”

And the personal benefits may be comparable with or even exceed the value of the environmental benefits. The healthcare benefits alone for a healthy global diet—a predominantly plant-based diet, a vegetarian, or a vegan diet—could exceed the price of the carbon saved. We’re talking up to $30 trillion dollars a year saved from the health benefits alone.

Now, if the health of yourself, the planet, and your own children doesn’t quite motivate you, consider you may also be facing threats to the global beer supply.

And, healthier diets don’t just reduce greenhouse gas emissions. Since “livestock production is the single largest driver of habitat loss,” reducing meat consumption is also the key to biodiversity conservation; ideally, perhaps, reducing demand for animal-based foods by increasing the proportions of plant-based foods up to like 90% of the diet.

Livestock production is also a leading cause of soil loss, and water and nutrient pollution. Yet it appears to be a “blind spot in water policy.” “Despite the fact that animal products form the single most important factor in humanity’s water footprint, water managers never seem to talk about meat [and] dairy.”

But it’s not just animal products. I mean, yes, at least 80% of the deforestation in the Amazon is to raise cattle, and grow feed crops like soybeans to export to other farm animals––but also to make vegetable oil, most of which is from palm and soy. Both crops have been expanding, resulting in massive deforestation. It just seems “particularly egregious if that deforestation takes place for the sake of junk food.”

Not everyone agrees we should be moving to healthier diets, though. The World Health Organization actually pulled out of the EAT-Lancet Commission because of their promotion of a global move to more plant-based foods. See, if we focused on promoting predominantly plant-based foods and excluding foods deemed unhealthy, including meat and other animal-based foods, such a diet could yeah, save 10 million lives a year, $30 trillion dollars, and help save the entire planet, but could lead to the loss of jobs linked to animal husbandry and the production of junk.

In our next story, we look at Is the purported decline of nutrients in our crops due to soil degradation, or is that just supplement industry propaganda?

Internet articles and the popular press frequently state that the mineral nutrient composition of crops has been declining over the past 50 years, with titles like “The great nutrient collapse,” blamed in part on the purported nutrient depletion of the soil. This narrative is touted by the leading dietary supplement trade association. But is it true?

This is probably the most cited study, comparing the nutrient content of US fruits and vegetables between 1950 and 1999, and about half, seven out of 13 nutrients tested, showed no significant decline, and the six that did only declined by about 15%, on average. A similar study in the UK looking at mineral content had similar findings with declines in about half. Of course, the drop in sodium doesn’t matter. We get too much as it is, and most people get more than enough copper. But the 10% drop in magnesium is significant. And though the drop in iron looks precipitous, the absolute drop is tiny, since fruits and veggies have so little to begin with.

Australian researchers had similar findings: a halving of iron in fruit over the last few decades. But the absolute drop is like 0.2 mg per serving, which is about 1/50th of the recommended daily allowance for most people. And the same with zinc. And there was actually an increase in grains. There was just a few milligrams difference in calcium and magnesium, where the RDA is in the hundreds of milligrams. So, with such small absolute differences, any true decrease in mineral content is unlikely to have a large impact on nutritional intake.

And, it’s not clear if these changes are even real. These comparisons of historical food composition tables are not a reliable way to determine changes in nutrient composition of foods over time, since they are just unmatched snapshots in time not meant to sync up. So, these may have been different varieties, or there may have been differences in ripeness, season, location. If you look at the levels of minerals in the soil itself, you don’t tend to see declining levels, and in some cases, we can actually see a significant rise in mineral levels nearly across the board over the last half century. So, where is this gloomy supplement industry propaganda coming from?

There’s been a concern that rising CO2 levels might reduce nutrients in crops, but the largest recorded change was a 59% increase in total antioxidant content, thanks to higher phytonutrient levels.

What about the concern that modern varieties grow so much larger and faster, potentially creating a trade-off between yield and nutrient concentration? One way to study this is to grow a whole bunch of different varieties released over the years under the same conditions, which is what these researchers did with broccoli. There were 14 cultivars released over 50 years, and they found there was no clear change over time in mineral content, though they did find that larger heads of broccoli did tend to have lower mineral content—something to keep in mind next time you shop.

As for the dietary supplement trade association’s claim that Americans don’t get the nutrients they need from foods? Well, for example, only half of Americans reach even 75 mg of vitamin C a day—less than the amount in a single orange. So, why aren’t Americans getting enough fruit and vegetable nutrients? Because they aren’t eating enough fruits and vegetables. They don’t need pills; they just need produce.

So, even if there really is 15% less vitamin C in today’s broccoli, that just may mean you have to eat six florets of today’s broccoli instead of five florets from yesteryear.