In 2019, a landmark EAT-Lancet report described how to nourish people and save the planet, proposing a “planetary health diet” consisting mostly of whole plant-based foods.
But a new study in The Lancet Planetary Health moves the science forward by suggesting the planetary health diet falls short in essential vitamins and minerals such as iron, zinc, calcium, and vitamin B12. For women aged 15–49 years, it provides just 55 percent of the recommended intakes. Deficiencies in these vitamins and minerals can lead to severe and lasting effects, including compromised immune systems and increased risk for infections; hindered child growth, development, and school performance; and decreased work productivity; all of which ultimately limit human potential.
The reason for these shortfalls is that animal source foods make up just 14 percent of the planetary health diet. Iron and zinc in beans, for example, are not as readily available for the body to use as iron and zinc in meat. The planetary health diet is likely to be highly protective against noncommunicable diseases such as obesity, heart disease, diabetes, and cancer, which are among the top contributors to the global burden of death and disease. However, this new study suggests it could unintentionally lead to another form of malnutrition, with its own public health burden.
Based on this finding, the researchers presented a hypothetical diet of what it would take to meet micronutrient requirements through whole foods alone. One option is to increase nutrient-dense animal source foods and reduce whole grains, legumes and nuts because they are high in phytate, which inhibits absorption of iron, zinc, and calcium. However, since they can protect against noncommunicable diseases, another strategy could be to reduce the phytate in these foods through crop breeding and processing, including soaking, fermenting and sprouting.
According to the EAT-Lancet report, however, these changes would increase the diet’s environmental impact, particularly the increase in red meat. Could this conundrum provide the incentive to inspire concerted approaches to produce more animal source foods sustainably than had been envisaged in the original report?
Other approaches and trade-offs must also be considered. For example, staple food fortification could be further improved and scaled to make up for shortfalls. While this cannot fully replicate the health benefits of intrinsically nutrient-dense foods, it could help bridge the gap in essential vitamins and minerals while being more environmentally sustainable.
Or can individuals just take a vitamin and mineral supplement to meet their needs? While this is a reasonable option for many, there are important considerations. First, supplements such as iron pills can have side effects. Second, iron supplements can exacerbate infections such as malaria if not properly treated simultaneously and only given to those with iron deficiency. And third, there are many practical constraints to be overcome to make supplements, and the necessary healthcare access, widely available worldwide.
Perhaps the most compelling evidence for the challenge of women aged 15–49 years consuming enough nutrients, particularly iron, is that over 20 percent in the US and UK are iron deficient. These are high-income countries where a diversity of healthy foods, healthcare and iron supplements are widely available, and where robust fortification policies and implementation are in place. Yet iron deficiency is still widespread.
So, what is the solution? Can a planetary health diet ever provide adequate vitamins and minerals? What is clear is that a combination of actions is needed to improve access to diverse nutrient dense and healthy foods. This includes increasing their desirability, convenience, safety and affordability through incentives and subsidies, improving fortification policies and implementation, and improving access to healthcare and supplements.
Is this possible? The evidence suggests it is. But efforts to achieve healthy and sustainable diets must ensure micronutrient adequacy using all the available approaches, tailor recommendations according to the local context, equitably involve local stakeholders impacted by any dietary or policy changes, and be transparent about trade-offs. Preserving human health and protecting our planet are more important now than ever. All of society must rise to the challenge, now, to address these integrally linked and equally important challenges.
Of course, it is possible, and it must be done. Sooner rather than later.
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Photo courtesy of Yoav Aziz, Unsplash