I recently gave a few lectures on micronutrients to different graduate classes, so I thought I'd post a thread with my slides.
Here's what I'll cover. Apologies if you've seen most of the slides before.
Undernutrition like stunting and anemia––which are caused in part due to micronutrient deficiencies––are widespread in low- and middle-income countries.
Many of us, even in high-income countries, are deficient in micronutrients, including iron, zinc, folate, and vitamins A, D, and B12, among others.
In lower income countries the vast majority of women are deficient in at least one micronutrient––9 in 10 women in India, Bangladesh, Pakistan, Cameroon, and Côte d'Ivoire. Even in the US and UK, 1 in 5 women are iron deficient.
This graph shows the global and regional prevalence. All regions for women and children are near 50% or higher––including high-income countries.
This graph shows the prevalence of isolated deficiencies and two or more deficiencies. Many women and children have multiple micronutrient deficiencies. In Pakistan 70% of women have two or more deficiencies.
This graph shows an example of individual deficiencies for children and adolescent girls in India. Over half are folate deficient folate. A third are iron deficient.
The data on estimated prevalence of inadequate intakes don't align perfectly with micronutrient deficiencies. But it's clear there are inadequacies in all countries. Current diets are not dense enough in micronutrients to meet requirements.
In the US, iron & zinc deficiency are common among women. Choline intake is below the adequate intake for 9 in 10 adults. Vitamin E, magnesium, & calcium intake is inadequate for much of the population. If we had inadequate intake for potassium it would also be inadequate.
In higher income countries micronutrient deficiencies are due in part to the high intakes of ultraprocessed foods, which are low in micronutrients, not to mention their effect on noncommunicable diseases.
Here we can see where purchase of ultraprocessed foods are highest: North America, much of Europe, Japan, Australia, and New Zealand.
In lower income countries micronutrient deficiencies are due in part to people not having access to diverse diets. They want healthy, nutrient dense foods but can't afford them or access them in markets.
Here we can see that minimum dietary diversity, an indicator of micronutrient adequacy is very low in India and many countries in Sub-Saharan Africa.
For a specific example, access to, and consumption of, fruit is very low in Africa and South Asia.
For pulses (beans, peas, lentils), consumption is low in most countries, including in the US.
Two points here: Animal source food intake is very low in South Asia and Sub-Saharan Africa; and unprocessed red meat intake is lower in high-income countries than the global average (it's highest in Central and Eastern Europe, Central Asia, Southeast Asia, and East Asia).
Current diets low in animal source foods are highly inadequate in micronutrients. Any efforts to restrict animal source foods need to ensure micronutrient adequacy.
Animal source foods are a particularly good source of omega 3, vitamins A and B12, iron, and zinc. Highly plant-based diets––even diverse diets––are often inadequate in omega 3, iron, zinc, and vitamin B12 due to low bioavailability.
The top sources of micronutrients commonly lacking worldwide, particularly in lower income countries are:
• Small fish
• Dark leafy greens
• Beef and goat
• Canned fish with bones and skin
Looking specifically at iron, the top sources are:
• Small dried fish
• Beef and goat
For folate, the top sources are:
• Dark leafy greens
• Orange, yellow, and red fruits & vegetables
• Other fruits
Here you can see the aggregate scores, which show animal source foods, dark leafy greens, and to a lesser extent pulses and certain traditional grains with the highest densities overall.
What's really interesting is to see a healthy plant-based planetary health diet fall short on certain nutrients, especially iron for women of reproductive age. We need to be careful that any diet we recommend for any reason meets basic requirements.
Increasing animal source foods and reducing phytate (from the baseline planetary health diet) are necessary to make the diet micronutrient adequate.
To conclude, dietary micronutrient inadequacies and corresponding deficiencies are widespread globally. The cause of this is different in higher income countries vs lower income countries. Consuming adequate plant and animal source foods helps ensure micronutrient adequacy.
Thanks for reading!
Initial thread 👇
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