| Total essential vitamins | 13 (4 fat-soluble, 9 water-soluble) (Dietary Reference Intakes, National Academies of Sciences) |
| Essential minerals (major + trace) | At least 16 recognized as essential (National Institutes of Health, Office of Dietary Supplements) |
| Most common U.S. deficiencies | Vitamin D, B12, iron, calcium (What We Eat in America, NHANES survey data) |
| Primary dietary strategy | Variety across food groups (Dietary Guidelines for Americans, USDA/HHS) |
| Special consideration — plant-based diets | Vitamin B12 supplementation often recommended (Academy of Nutrition and Dietetics position paper) |
What Are Micronutrients?
Micronutrients are vitamins and minerals your body needs in relatively small amounts — but their impact on health is anything but small. Unlike macronutrients (carbohydrates, proteins, and fats), micronutrients don't provide calories. Instead, they act as essential partners in virtually every biological process, from converting food into energy to building bone tissue and supporting immune defense. See our guide to macronutrients for how the two categories work together.
The word essential has a specific meaning here: the body either cannot synthesize these nutrients at all, or cannot produce them in quantities sufficient for good health. That means they must come primarily from food — and in some cases, from supplements under medical guidance.
Micronutrients fall into two broad categories. Vitamins are organic compounds (meaning they contain carbon) and can be broken down by heat, air, or acid. Minerals are inorganic elements that retain their structure through cooking and digestion. Both are covered in this reference. If you're newer to thinking about nutrients as a whole, our nutrition fundamentals guide offers useful grounding.
| Total essential vitamins | 13 (4 fat-soluble, 9 water-soluble) (Dietary Reference Intakes, National Academies of Sciences) |
| Essential minerals (major + trace) | At least 16 recognized as essential (National Institutes of Health, Office of Dietary Supplements) |
| Most common U.S. deficiencies | Vitamin D, B12, iron, calcium (What We Eat in America, NHANES survey data) |
| Primary dietary strategy | Variety across food groups (Dietary Guidelines for Americans, USDA/HHS) |
| Special consideration — plant-based diets | Vitamin B12 supplementation often recommended (Academy of Nutrition and Dietetics position paper) |
Key Vitamins: Roles and Food Sources
Vitamins are divided into two groups based on how the body stores them:
- Fat-soluble vitamins (A, D, E, K) dissolve in fat and are stored in body tissues. Because the body accumulates them, both deficiency and excess can have health consequences.
- Water-soluble vitamins (C and the eight B vitamins) dissolve in water, are not stored in large amounts, and excess quantities are generally excreted in urine — making regular dietary intake especially important.
Vitamin A
Supports vision (especially in low light), immune function, and cell growth. Found in liver, dairy products, and eggs; the body also converts beta-carotene from orange and dark-green vegetables into vitamin A.
B Vitamins
The B-vitamin family — including B1 (thiamine), B2 (riboflavin), B3 (niacin), B6, B12, and folate — collectively supports energy metabolism, red blood cell production, and nervous system function. Whole grains, legumes, leafy greens, meat, fish, and dairy are major sources. Vitamin B12 is found almost exclusively in animal products, making it a nutrient of particular attention for people following plant-based diets.
Vitamin C
An antioxidant that supports immune function, wound healing, and iron absorption. Citrus fruits, bell peppers, strawberries, and broccoli are among the richest sources.
Vitamin D
Supports calcium absorption and bone health, and plays roles in immune regulation. The skin synthesizes vitamin D when exposed to sunlight; dietary sources include fatty fish, fortified dairy, and egg yolks. Deficiency is relatively common, particularly in northern climates with limited sun exposure.
Vitamin K
Essential for blood clotting and bone metabolism. Leafy green vegetables — kale, spinach, collard greens — are among the most concentrated food sources.
Micronutrient
A vitamin or mineral the body requires in small quantities to function properly. Unlike macronutrients, micronutrients provide no calories but are essential for countless biological processes.
Fat-soluble vitamin
A vitamin (A, D, E, or K) that dissolves in fat and is stored in the liver and fatty tissues. Because these accumulate in the body, both persistent deficiency and excessive intake can be problematic.
Water-soluble vitamin
A vitamin (C or any of the B vitamins) that dissolves in water and is not significantly stored by the body. Excess amounts are typically excreted in urine, so regular dietary intake is important.
Trace mineral
A mineral the body needs in very small amounts — typically less than 100 mg per day. Examples include iron, zinc, iodine, and selenium. Small quantities does not mean less important; deficiencies can have serious health effects.
Bioavailability
The proportion of a nutrient that the body actually absorbs and uses after consumption. Bioavailability varies by food form, preparation method, and individual factors such as age and digestive health.
Dietary Reference Intake (DRI)
A set of reference values established by the National Academies of Sciences to quantify nutrient needs for healthy populations. Includes Recommended Dietary Allowances (RDAs) and Tolerable Upper Intake Levels (ULs).
Essential Minerals: Why They Matter
Minerals are categorized by how much the body requires. Macrominerals (such as calcium, magnesium, and potassium) are needed in larger amounts; trace minerals (such as iron, zinc, selenium, and iodine) are required in far smaller quantities but are no less critical.
~42%
U.S. adults with vitamin D insufficiency
Analysis of NHANES data published in Nutrition Research estimated that roughly 42% of American adults have insufficient vitamin D levels.
2 billion
People worldwide affected by iron deficiency
The World Health Organization identifies iron deficiency as the most prevalent nutritional disorder globally.
Up to 30%
Reduction in B12 absorption with age
The National Institute on Aging notes that the ability to absorb vitamin B12 from food can decline significantly in older adults due to changes in stomach acid production.
Calcium
The most abundant mineral in the body, primarily stored in bones and teeth. Also involved in muscle contraction and nerve signaling. Dairy products, fortified plant milks, sardines, and leafy greens (such as bok choy and kale) are reliable sources.
Iron
Central to hemoglobin, the protein in red blood cells that carries oxygen. Heme iron from meat and fish is absorbed more readily than non-heme iron from plant sources; pairing plant iron sources with vitamin C can improve absorption.
Magnesium
Involved in more than 300 enzymatic reactions, including energy production and muscle function. Nuts, seeds, whole grains, and leafy greens are good sources.
Zinc
Supports immune function, wound healing, and the sense of taste and smell. Found in meat, shellfish, legumes, seeds, and fortified cereals.
Iodine
Required for thyroid hormone production, which regulates metabolism. Iodized salt, seafood, and dairy are primary sources in the American diet.
Because micronutrient needs interact with how well the body absorbs and uses nutrients, hydration is also relevant — explore how water fits into nutrition for broader context.
Deficiencies: What to Know
Micronutrient deficiencies vary in severity. Some develop gradually over months or years; others can appear more quickly when intake or absorption is significantly impaired. Common deficiencies in the U.S. include vitamin D, vitamin B12, iron, and calcium, according to federal dietary survey data.
Certain populations carry higher risk: older adults (who may absorb B12 less efficiently), people who are pregnant or nursing (with increased folate and iron needs), those following restrictive diets, and individuals with conditions affecting nutrient absorption.
Signs of deficiency depend on which nutrient is low. Fatigue, for example, is associated with iron and B12 deficiency; brittle bones with inadequate calcium and vitamin D; poor wound healing with vitamin C. However, these symptoms overlap with many other conditions — a healthcare provider should assess any concerns, not self-diagnosis.
Supplementation can help fill gaps in specific circumstances, but more is not always better. Some micronutrients have established tolerable upper intake levels; exceeding them can cause adverse effects. Anyone considering supplements should discuss this with a qualified healthcare professional.
A practical starting point is simply variety: building a balanced plate across food groups is broadly recognized as the most sustainable way to meet micronutrient needs without over-relying on any single food or supplement.
This article is for general informational and educational purposes only and is not a substitute for professional medical or dietary advice. Consult a qualified healthcare provider if you have questions about your individual nutritional needs, symptoms, or supplement use.