Micronutrients are vitamins and minerals. That’s the complete list of categories: every micronutrient your body needs falls into one of those two groups. Unlike macronutrients (protein, carbohydrates, and fat), which you need in gram-sized amounts every day, micronutrients are required in very small quantities, often measured in milligrams or even micrograms. Despite the tiny doses, they’re essential for producing enzymes, hormones, and other substances that keep your body functioning.
Vitamins: Water-Soluble and Fat-Soluble
There are 13 essential vitamins, split into two groups based on how your body absorbs and stores them.
Water-soluble vitamins dissolve in water and aren’t stored in significant amounts. Your body uses what it needs and flushes the rest through urine, so you need a steady supply from food. This group includes:
- Vitamin C
- The eight B vitamins: B-1 (thiamin), B-2 (riboflavin), B-3 (niacin), B-5 (pantothenic acid), B-6, B-7 (biotin), B-9 (folate), and B-12
Fat-soluble vitamins dissolve in fat, not water. They’re absorbed alongside dietary fats and can be stored in your liver and fatty tissue for weeks or months. This group includes vitamins A, D, E, and K. Because your body holds onto them, it’s possible to accumulate too much over time, particularly with supplements. For adults, the tolerable upper intake for vitamin A from supplements is 3,000 micrograms per day, and for vitamin E it’s 1,000 milligrams per day. Vitamin K has no established upper limit because there isn’t enough data to set one.
Minerals: Macrominerals and Trace Minerals
Minerals are inorganic elements that come from soil and water, eventually making their way into the plants and animals you eat. Like vitamins, they split into two subgroups based on how much your body requires.
Macrominerals are needed in larger amounts (typically hundreds of milligrams daily). There are seven:
- Calcium
- Phosphorus
- Magnesium
- Sodium
- Potassium
- Chloride
- Sulfur
Trace minerals are needed in much smaller amounts, sometimes just micrograms. The essential trace minerals include iron, zinc, copper, manganese, iodine, selenium, cobalt, and fluoride. “Trace” doesn’t mean optional. Iron deficiency is one of the most common nutritional deficiencies worldwide, and inadequate iodine or zinc can have serious consequences for growth and immune function.
What Micronutrients Actually Do in Your Body
Micronutrients aren’t fuel. They don’t provide calories. Instead, they act as helpers that make your body’s chemical reactions possible. Their roles fall into a few broad categories.
Many work as cofactors or coenzymes, meaning they sit inside enzymes and make those enzymes function. Zinc alone is a cofactor for over 100 different enzymes. B vitamins like riboflavin and niacin are essential parts of the chain your cells use to convert food into usable energy. Folate handles the transfer of small molecular groups needed to build DNA and process amino acids.
Several micronutrients protect your cells from oxidative damage. Normal metabolism constantly generates reactive molecules (free radicals) that can harm cell membranes and DNA. Vitamin E directly neutralizes these molecules in cell membranes, while selenium is built into an enzyme that cleans up oxidative byproducts. Vitamin A, in its carotenoid form, also quenches free radicals.
Zinc plays a particularly wide role. It’s needed for protein synthesis, insulin response, glucose metabolism, and even gene regulation. Zinc-containing proteins called “zinc fingers” bind to DNA and control when certain genes are switched on or off, including genes for steroid hormone receptors.
Best Food Sources by Nutrient
A varied diet generally covers your micronutrient needs. Here’s where to find the key ones:
- Vitamin A: sweet potatoes, carrots, spinach, eggs, liver
- B vitamins: meat, poultry, fish, whole grains, legumes, eggs, dairy
- Vitamin C: citrus fruit, bell peppers, strawberries, broccoli, tomatoes
- Vitamin D: fatty fish, fortified milk and cereals
- Vitamin E: vegetable oils, nuts, leafy greens, whole grains
- Vitamin K: kale, spinach, broccoli, cabbage, eggs
- Calcium: dairy products, salmon, leafy greens
- Magnesium: spinach, legumes, seeds, whole-wheat bread
- Potassium: fruits, vegetables, meat, milk, legumes
- Iron and zinc: meat, poultry, fish, legumes, whole grains
You’ll notice that leafy greens, legumes, whole grains, and animal proteins show up repeatedly. These are the most micronutrient-dense food groups overall.
Why Absorption Matters as Much as Intake
Eating a micronutrient and actually absorbing it are two different things. Several factors affect how much your body takes in.
Fat-soluble vitamins (A, D, E, K) require dietary fat for absorption. They go through a process involving bile acids in your gut that forms tiny droplets your intestines can absorb. Eating these vitamins with some fat, even a small amount like olive oil on a salad, significantly improves uptake. Any condition that reduces bile production can inhibit absorption of these vitamins.
Vitamin C enhances iron absorption, which is why pairing iron-rich foods with citrus or peppers is a common nutrition recommendation. Vitamin C also helps mobilize stored iron and reduces iron’s tendency to cause oxidative stress.
On the other hand, several compounds in plant foods reduce mineral absorption. Phytic acid, found in legumes, cereal grains, and seeds, binds to calcium, zinc, and iron and dramatically reduces how much your intestines can take up. Polyphenols (found in tea, coffee, and many fruits), fiber, and lignins can also interfere. High-fiber diets can inhibit absorption of fat-soluble vitamins like D and E as well. This doesn’t mean you should avoid fiber or plant foods. Cooking, soaking, and fermenting grains and legumes breaks down phytic acid, and the overall nutritional benefits of these foods far outweigh the absorption trade-offs.
When Your Body Needs More
Micronutrient needs aren’t static. Physical stress like acute infection, surgery, or trauma increases your body’s energy expenditure and protein breakdown. That ramps up the demand for water-soluble vitamins, since they serve as coenzymes in the metabolic pathways handling that increased workload. Trace element requirements rise in parallel.
Pregnancy and breastfeeding also increase needs for folate, iron, calcium, and several other micronutrients. Strict plant-based diets can make it harder to get adequate B-12 (found almost exclusively in animal products) and may reduce mineral bioavailability due to higher phytate intake. People on very restricted diets, those with digestive conditions affecting absorption, and older adults with reduced food intake are the groups most likely to fall short.