Key Takeaways
Start here
What Are Micronutrients?
Next
Vitamins: Fat-Soluble vs. Water-Soluble
Then
Minerals: Major and Trace
Building on that
Where Do Micronutrients Come From?
Finally
When Gaps Happen: Deficiency and Excess
What Are Micronutrients?
Your body runs on two broad categories of nutrients: macronutrients — carbohydrates, protein, and fat — which provide energy and structural building blocks, and micronutrients, which are the vitamins and minerals that enable virtually every biological process. If macronutrients are the fuel, micronutrients are the engine components that keep everything running. You can learn more about the other side of this equation in our overview of macronutrients.
The term "micro" refers to quantity, not importance. Vitamins and minerals are needed in milligram or microgram amounts — tiny fractions compared to the grams of carbohydrates or protein a person consumes daily. Yet their absence or insufficiency can have significant consequences for health.
Critically, the human body cannot synthesize most micronutrients on its own. A few partial exceptions exist — the skin can produce vitamin D in response to sunlight, and the gut microbiome generates small amounts of vitamin K — but even these are inconsistent and rarely sufficient. The rest must come entirely from what you eat and drink.
Micronutrient
A vitamin or mineral the body needs in small amounts to function properly. Most cannot be made by the body and must come from food.
Fat-soluble vitamin
A vitamin (A, D, E, or K) that dissolves in fat and is stored in body tissues. These accumulate over time, so excess supplementation can be harmful.
Water-soluble vitamin
A vitamin (C or any B vitamin) that dissolves in water and is not stored long-term. Surplus amounts are excreted in urine, so regular dietary intake matters.
Trace mineral
A mineral the body needs in very small quantities — such as iron, zinc, or iodine. Small as the requirement is, a lack of these can still significantly affect health.
Bioavailability
How much of a nutrient the body actually absorbs and uses after you consume it. The same nutrient can have different bioavailability depending on the food source or how it's prepared.
Fortified food
A food that has had one or more nutrients added to it during processing — for example, calcium added to orange juice or vitamin D added to milk.
Vitamins: Fat-Soluble vs. Water-Soluble
There are 13 vitamins recognized as essential for humans. They split into two groups based on how the body handles them:
Fat-Soluble Vitamins (A, D, E, K)
These vitamins dissolve in fat and are stored in the liver and fatty tissues. Because the body holds reserves, you don't need to consume them every single day — but that storage capacity also means overconsumption, especially through supplements, can build to harmful levels over time.
- Vitamin A supports vision, immune function, and cell growth. Found in liver, dairy, and orange-yellow produce.
- Vitamin D regulates calcium absorption and plays a role in immune defense. Dietary sources include fatty fish and fortified foods; sunlight also triggers skin production.
- Vitamin E acts as an antioxidant and supports immune function. Nuts, seeds, and vegetable oils are primary sources.
- Vitamin K is essential for blood clotting and bone metabolism. Leafy greens are the richest dietary source.
Water-Soluble Vitamins (C and the B Vitamins)
These dissolve in water and are not stored in significant amounts — excess is excreted through urine. That means they need more consistent replenishment through diet. The B vitamins include B1 (thiamin), B2 (riboflavin), B3 (niacin), B5, B6, B7 (biotin), B9 (folate), and B12. Together they support energy metabolism, nervous system function, and red blood cell production. Vitamin C is critical for immune function, collagen synthesis, and antioxidant protection.
Minerals: Major and Trace
Minerals are inorganic elements — they originate in the soil and water and enter the food supply through plants and animals. They're divided by how much the body requires:
Major Minerals
The body needs these in larger amounts (generally more than 100 mg per day). They include calcium, phosphorus, magnesium, sodium, potassium, chloride, and sulfur. Calcium and phosphorus make up the bulk of bone structure. Magnesium is involved in hundreds of enzyme reactions. Sodium and potassium work together to regulate fluid balance and nerve signals.
Trace Minerals
Required in much smaller amounts, but no less important. Iron carries oxygen in the blood; without enough, fatigue and anemia follow. Zinc supports immune response and wound healing. Iodine is essential for thyroid hormone production. Selenium, copper, manganese, fluoride, and chromium round out this group, each with specific functions in metabolism, antioxidant defense, or structural roles.
Pair Iron-Rich Foods with Vitamin C
Plant-based iron (called non-heme iron) is less readily absorbed than the iron found in meat. Eating iron-rich plant foods — like lentils, spinach, or fortified cereals — alongside a source of vitamin C (citrus, bell peppers, tomatoes) can meaningfully improve absorption. This is a simple, food-based strategy worth building into everyday meals.
Where Do Micronutrients Come From?
Whole, minimally processed foods provide the widest variety of micronutrients. No single food contains everything the body needs, which is why dietary diversity matters so much. A few practical patterns:
- Leafy greens (spinach, kale, chard) are rich in vitamins K, C, and folate, plus magnesium and iron.
- Fatty fish (salmon, sardines, mackerel) deliver vitamin D, B12, and selenium.
- Legumes and beans offer iron, folate, zinc, and magnesium.
- Dairy and fortified plant milks are major sources of calcium, vitamin D, and B12.
- Nuts and seeds provide vitamin E, magnesium, zinc, and selenium.
- Citrus fruits and berries are concentrated sources of vitamin C.
Fortified foods — such as breakfast cereals, plant-based milks, and enriched grain products — also contribute meaningfully to micronutrient intake, particularly for nutrients like B12, D, and iron that can be harder to obtain in sufficient amounts from unfortified diets. For a closer look at how food labels communicate nutrient content, see our guide to nutrition label terms.
When Gaps Happen: Deficiency and Excess
Micronutrient inadequacy is more common than outright deficiency, and it often goes unnoticed. Dietary patterns that rely heavily on processed foods and lack variety are associated with lower intake of several key vitamins and minerals simultaneously.
Certain populations face higher risks: pregnant people need substantially more folate and iron; older adults absorb vitamin B12 less efficiently; people with limited sun exposure often have lower vitamin D; and those following plant-based diets need to pay particular attention to B12, iron, calcium, zinc, and omega-3s. For a detailed, lookup-friendly reference on each vitamin and mineral's role and food sources, our plain-language micronutrient reference guide is a practical companion to this overview.
More Is Not Always Better with Supplements
Supplements are not regulated the same way pharmaceuticals are, and many over-the-counter products contain doses far above what the body needs. Fat-soluble vitamins and certain minerals can accumulate to toxic levels with sustained over-supplementation. Taking high-dose supplements without confirmed deficiency or medical supervision is generally not recommended.
If you're concerned about your micronutrient status, a healthcare provider can order targeted blood tests to identify actual deficiencies rather than relying on guesswork. Self-directed high-dose supplementation carries real risks — especially with fat-soluble vitamins and minerals like iron — and is best approached with professional guidance.
This article is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your individual nutritional needs or health conditions.