Four key nutrients missing from diets of two-thirds of adults: ‘alarming’

New research shows that about two-thirds of adults worldwide don’t get enough of four key nutrients.

The findings, published in the journal The Lancet Global Health, are part of a broader study of global deficiencies of 15 key micronutrients and their consequences for human health.

“These results are alarming,” Ty Beal, senior technical specialist at the Global Alliance for Improved Nutrition and one of the study’s co-authors, said in a statement.

“Most people, even more than previously thought, in all regions and countries of all incomes, do not consume enough of several essential micronutrients. These gaps jeopardize health outcomes and limit human potential globally,” Beal said.

The study analyzed data from the Global Dietary Database, the World Bank, and nutrition surveys to estimate dietary intakes of 15 key vitamins and minerals in 185 countries. The results showed that more than 5 billion people worldwide do not get enough iodine, vitamin E, or calcium from their diets, and more than 4 billion people do not get enough iron.

But why are these nutrients so important and what foods can we eat to ensure we get enough of them?

Iodine

Iodine is an essential mineral that our bodies need to make thyroid hormones. These hormones play a key role in regulating our metabolism, which in turn affects our ability to regulate our body temperature, heart health, brain development, and body weight, among other things. And yet, 68 percent of the world’s population doesn’t get enough of it, at least not through diet.

It is important to note that the study did not take into account nutrient intake through fortification and supplementation, as many people in the US rely on these substances to meet their daily nutritional needs.

Interestingly, women were found to be significantly more likely to be deficient in iodine than men.

The recommended daily allowance of iodine is 150 micrograms per day and 220 micrograms per day for pregnant women, with a recommended upper limit of 1,100 micrograms. So what foods can you eat to reach these recommendations?

• According to the National Institutes of Health, fish (cod) is particularly high in iodine, with about 146 micrograms in one serving.
• Seaweed – two tablespoons of dried nori contain 116 micrograms.
• Dairy: One serving of plain Greek yogurt contains about 87 micrograms, while a cup of skim milk contains 84 micrograms.
• Eggs: One large hard-boiled egg contains 31 micrograms.
• Shrimp – 85 grams contains 13 micrograms.

In the US, many foods are also fortified with iodine, including certain breads and iodized salt.

Vitamin E

Vitamin E is a fat-soluble vitamin that plays an important role in clearing reactive waste products from metabolic reactions (called free radicals), which can cause damage to our cells. It is also involved in supporting our immune system and communication between our cells.

The recommended daily allowance of vitamin E is 15 milligrams, with an upper limit of 1,000 mg.

Serious vitamin E deficiencies are rare in the U.S., but previous research has shown that most Americans aren’t getting their recommended daily intake. According to the new study, 67 percent of adults worldwide aren’t getting enough of this essential vitamin in their diets. Fortunately, there are plenty of foods you can choose from to help you reach your daily goals:

• Seeds: 28 grams of dry, roasted sunflower seeds contains 7.4 mg, almost half of your daily value.
• Nuts – 1 ounce of dry roasted almonds contains 6.8 mg, while 1 ounce of peanuts contains 2.2 mg. Peanut butter is also rich in this vitamin, with 2.9 mg in two tablespoons.
• Spinach – half a cup cooked contains 1.9 mg.
• Broccoli – half a cup cooked provides 1.2 mg.
• Kiwi: One kiwi contains 1.1 mg (and 71 percent of your daily vitamin C intake).

Because vitamin E is fat-soluble, you’ll get the most benefit from these foods if you eat them with something rich in healthy fats, such as avocado, fatty fish, or olive oil.

Calcium

Calcium plays an important role in bone health, as well as circulation, muscle function, hormone secretion and communication in our nervous system. Yet 66 percent of adults worldwide do not get enough of it in their diets.

The recommended daily allowance for adults under 50 is 1,000 mg per day, rising to 1,200 mg for those over 50. More than 2,500 mg per day can cause gastrointestinal problems and possibly increase your risk of heart disease, but it’s difficult to exceed this limit through diet alone.

In the U.S., about 72 percent of our calcium intake comes from dairy products: a serving of plain yogurt contains about a third of the RDI, while a cup of milk contains about a quarter. However, there are other sources as well:

• Fatty fish – Three ounces of sardines contains 325 mg of calcium, or a quarter of your daily recommendation. The same amount of salmon provides 181 mg.
• Soybeans – One-half cup of cooked soybeans contains 131 mg.
• Green leafy vegetables: Half a cup of cooked spinach contains 123 mg, while a cup of cooked kale contains 94 mg.
• Chia seeds – one tablespoon of chia seeds contains 76 mg.
• Beans – One-half cup of canned pinto beans contains 54 mg.

The amount of calcium we can absorb varies by food. In order to absorb calcium, your body needs sufficient vitamin D.

Iron

Our bodies need iron to transport oxygen through our blood. It also plays an important role in muscle metabolism, physical growth, brain development, and hormone production, among other things.

Iron deficiency, also called anemia, affects about 4 to 5 million Americans each year, according to research published in the online journal PLOS One. Menstruating women are particularly vulnerable to iron deficiencies, often characterized by fatigue, dizziness, sensitivity to cold and shortness of breath.

The recommended daily allowance for adults is 8 mg per day for men, 18 mg for women, and 27 mg for pregnant women, with an upper limit of 45 mg for most adults. However, 65 percent of adults worldwide do not get enough iron from their diet.

Foods rich in iron include:

• Shellfish: 3 ounces of oysters contains 8 mg of iron, 100 percent of the recommended daily amount for men and almost half of the recommended daily amount for women.
• Beans: One cup of white beans contains 8 mg of iron, while one cup of kidney beans contains 4 mg.
• Lentils – One cup of cooked lentils contains 6 mg.
• Spinach – Half a cup of cooked spinach contains 3 mg.
• Beef – 85 grams of beef contains 2 mg.

Many breakfast cereals are also fortified with iron.

Reference

Passarelli, S., Free, C. M., Shepon, A., Beal, T., Batis, C., & Golden, C. D. (2024). Global estimates of dietary micronutrient deficiencies: a modeling analysis. The Lancet Global Health.

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