Micronutrients at a Glance: Vitamins and Minerals Every Adult Should Know
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In this article
A plain-language reference covering key vitamins and minerals, what they do, and where to find them in everyday foods.
What Are Micronutrients and Why Do They Matter?
Micronutrients are the vitamins and minerals your body needs in relatively small amounts — but their impact is anything but minor. They drive hundreds of biochemical processes: converting food into energy, building bone, supporting immune defense, and regulating cell growth. Unlike macronutrients (carbohydrates, protein, and fat), micronutrients provide no calories, yet without them those macronutrients couldn't do their jobs. For a broader look at how these two nutrient categories work together, see how macronutrients and micronutrients complement each other.
Vitamins are organic compounds (meaning they come from living sources) and are divided into two groups based on how the body handles them:
- Fat-soluble vitamins (A, D, E, K): stored in body fat and the liver, so they don't need to be consumed every single day.
- Water-soluble vitamins (C and the eight B vitamins): not stored in large amounts, making regular dietary intake especially important.
Minerals are inorganic elements absorbed from soil and water through the foods we eat. They fall into two practical categories: major minerals (such as calcium, magnesium, and potassium), needed in larger quantities, and trace minerals (such as iron, zinc, and iodine), needed in smaller but still essential amounts.
Micronutrient
A vitamin or mineral that the body needs in small quantities to function properly. Unlike macronutrients, micronutrients supply no energy (calories) but are essential for hundreds of metabolic processes.
Fat-soluble vitamin
A vitamin (A, D, E, or K) that dissolves in fat and is stored in body tissues. Because they accumulate, excessive supplementation can lead to toxicity over time.
Water-soluble vitamin
A vitamin (C or any of the eight B vitamins) that dissolves in water and is not stored in significant amounts. Regular dietary intake is important because excess is generally excreted in urine.
Trace mineral
A mineral required by the body in very small amounts — typically less than 100 mg per day. Iron, zinc, iodine, and selenium are common examples. Small as the required amounts are, deficiencies can have serious health consequences.
Bioavailability
The proportion of a nutrient that the body actually absorbs and uses after consumption. Bioavailability varies by food source, preparation method, and the presence of other nutrients eaten at the same meal.
Recommended Dietary Allowance (RDA)
The average daily intake level of a nutrient considered sufficient to meet the needs of nearly all healthy adults. RDAs are set by the National Academies of Sciences, Engineering, and Medicine and vary by age and sex.
Key Vitamins: Functions and Food Sources
The table below summarizes the most important vitamins for adult health, what each one does, and where to find it in everyday foods.
| Vitamin | Primary Role | Common Food Sources |
|---|---|---|
| Vitamin A | Vision, immune function, skin cell turnover | Sweet potato, carrots, dark leafy greens, liver, eggs |
| Vitamin D | Calcium absorption, bone health, immune regulation | Fatty fish, egg yolks, fortified milk and cereals |
| Vitamin E | Antioxidant protection, immune support | Sunflower seeds, almonds, vegetable oils, spinach |
| Vitamin K | Blood clotting, bone metabolism | Kale, broccoli, Brussels sprouts, fermented foods |
| Vitamin C | Collagen synthesis, antioxidant, immune defense | Citrus fruits, bell peppers, strawberries, broccoli |
| B1 (Thiamine) | Energy metabolism, nerve function | Whole grains, pork, legumes, fortified cereals |
| B2 (Riboflavin) | Energy production, cellular growth | Dairy products, eggs, lean meats, almonds |
| B3 (Niacin) | DNA repair, energy metabolism | Chicken, tuna, peanuts, whole grains |
| B6 | Protein metabolism, neurotransmitter production | Chickpeas, banana, poultry, potatoes |
| B9 (Folate) | DNA synthesis, red blood cell formation | Lentils, leafy greens, asparagus, fortified grains |
| B12 | Nerve function, red blood cell formation | Meat, fish, dairy, eggs, fortified plant milks |
Vitamin D and B12 are among the nutrients most commonly underconsumed in US diets. Learn more in our companion article on nutrients most Americans don't get enough of.
Essential Minerals: Functions and Food Sources
Minerals support structural roles (like calcium in bone) as well as regulatory ones (like potassium balancing fluid levels). Here's a quick-reference overview:
| Number of recognized vitamins | 13 essential vitamins (National Institutes of Health, Office of Dietary Supplements) |
| Fat-soluble vitamins | A, D, E, K |
| Most common mineral deficiency globally | Iron deficiency (World Health Organization) |
| Vitamin D — primary natural source | Skin synthesis from sunlight (UVB) (National Institutes of Health, Office of Dietary Supplements) |
| B12 absorption risk group | Adults 50+ and strict vegans (Dietary Guidelines for Americans) |
| Potassium daily adequate intake (adult) | 2,600–3,400 mg depending on sex (National Academies of Sciences, Engineering, and Medicine, 2019) |
| Mineral | Primary Role | Common Food Sources |
|---|---|---|
| Calcium | Bone and tooth structure, muscle contraction | Dairy, fortified plant milks, tofu, leafy greens |
| Magnesium | Enzyme reactions, muscle and nerve function, blood sugar regulation | Pumpkin seeds, black beans, whole grains, spinach |
| Potassium | Fluid balance, heart rhythm, blood pressure regulation | Bananas, sweet potatoes, white beans, avocado |
| Iron | Oxygen transport in blood, energy metabolism | Red meat, lentils, tofu, fortified cereals |
| Zinc | Immune function, wound healing, protein synthesis | Oysters, beef, pumpkin seeds, chickpeas |
| Iodine | Thyroid hormone production, metabolic regulation | Iodized salt, seafood, dairy, eggs |
| Selenium | Antioxidant defense, thyroid function | Brazil nuts, tuna, sunflower seeds, eggs |
Several of these minerals — particularly potassium and magnesium — appear in nutrients many American adults aren't getting enough of, largely because processed foods crowd out the whole-food sources richest in them.
This article is for general informational purposes only and is not medical or nutritional advice. Talk to a registered dietitian or your healthcare provider if you have questions about your individual nutrient needs.
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Food & Drinks Editorial Team
Food & Drinks Editorial Team is the collective byline for our editorial team and contributor network. Articles published under this byline or an editorial pen name are researched, written, and reviewed according to our editorial standards for clarity, consistency, and independence before publication.
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