Why Vitamins and Minerals Matter

Vitamins and minerals are micronutrients — compounds your body needs in relatively small amounts but can't function without. Unlike carbohydrates, proteins, and fats, most micronutrients aren't used directly for energy. Instead, they act as the behind-the-scenes workers that keep your cells dividing correctly, your immune system primed, your bones dense, and your nerves firing on cue.

Because the roles they play are so varied, deficiencies in different nutrients show up differently — fatigue, brittle nails, frequent illness, slow wound healing, or muscle cramps, among others. Understanding the basics helps you connect symptoms to possible gaps and make smarter food choices. For a broader foundation, see Understanding Nutrition for the First Time.

Micronutrient

Vitamins and minerals that the body needs in small quantities to function properly. Unlike macronutrients, they provide no direct caloric energy but are essential for nearly every biological process.

Fat-soluble vitamin

Vitamins A, D, E, and K, which dissolve in dietary fat and are stored in the liver and fatty tissue. Because they accumulate in the body, both deficiency and excess supplementation can cause harm over time.

Water-soluble vitamin

Vitamin C and the eight B vitamins, which dissolve in water and are not stored in large amounts. Excess is generally excreted in urine, making regular dietary intake important.

Daily Value (DV)

A reference number established by the FDA representing a general daily intake goal for a nutrient, used on Nutrition Facts labels. It allows easy comparison across foods without needing to track milligrams.

Trace mineral

Essential minerals the body requires only in very small amounts, such as iron, zinc, selenium, and iodine. Despite the tiny quantities needed, a shortage can significantly affect health.

Fortified food

A food product to which vitamins or minerals have been added that weren't originally present or were removed during processing. Common examples include fortified milk (vitamin D) and enriched flour (B vitamins, iron).

Key Vitamins: Functions, Sources, and Deficiency Signs

Vitamins split into two categories based on how the body stores them:

  • Fat-soluble vitamins (A, D, E, K) dissolve in fat and are stored in body tissue. Because they accumulate, both deficiency and excessive supplementation can cause problems.
  • Water-soluble vitamins (C and all eight B vitamins) dissolve in water and aren't stored long-term, so regular dietary intake matters more.
Vitamin D primary source Sunlight synthesis + fortified foods and fatty fish (NIH Office of Dietary Supplements)
Vitamin C — role Collagen formation, immune support, iron absorption (NIH Office of Dietary Supplements)
Vitamin B12 — key concern Deficiency risk higher for older adults and those eating no animal products (NIH Office of Dietary Supplements)
Vitamin A — deficiency sign Night blindness; dry eyes in more severe cases (World Health Organization)
Folate (B9) — critical window Essential before and during early pregnancy to reduce neural tube defect risk (CDC, US Preventive Services Task Force)
Vitamin K — primary function Blood clotting and bone metabolism (NIH Office of Dietary Supplements)

For a deeper look at how these two categories differ structurally and functionally, see Vitamins vs. Minerals: Understanding the Difference.

This article is for informational and educational purposes only and is not a substitute for advice from a qualified healthcare professional. If you have concerns about nutritional deficiencies or symptoms, consult your doctor or a registered dietitian.

Key Minerals: Functions, Sources, and Deficiency Signs

Minerals are inorganic elements that come from soil and water and make their way into your body through food. They fall into two groups:

  • Macrominerals — calcium, magnesium, phosphorus, sodium, potassium, chloride, and sulfur — needed in larger amounts.
  • Trace minerals — iron, zinc, selenium, iodine, copper, and manganese — needed in smaller but still essential amounts.

Several minerals are consistently under-consumed in the American diet. Potassium, calcium, and magnesium are among the most notable gaps. Learn which nutrients many Americans fall short on in Nutrients That Many Americans Don't Get Enough Of.

~42%

US adults estimated to be vitamin D deficient or insufficient

Based on NHANES data analyzed in research published in Nutrition Research, using a serum 25(OH)D threshold.

~3%

US adults meeting the adequate intake for potassium

According to dietary intake data reviewed in the 2020–2025 Dietary Guidelines for Americans.

~10%

US women of childbearing age with iron deficiency

Estimated by the CDC based on NHANES surveillance data.

Using Food Labels and Food Choices Together

Nutrition facts panels list vitamins and minerals as a percentage of the Daily Value (DV) — a reference amount set by the FDA for a general adult diet. A food with 20% DV or more of a nutrient is considered a high source; 5% DV or less is low. These percentages give you a quick sense of how a given food fits into your overall intake without requiring you to memorize milligrams.

To get the most from that label, see Reading a Nutrition Facts Label Without the Confusion, which walks through every panel section in plain language. You can also read ingredient lists more strategically to spot fortified foods and understand what terms like "enriched" and "fortified" actually mean.

For comprehensive guidance on building a nutrient-rich diet, explore the Nutrition & Diet hub.