Complete Guide to Vitamins and Minerals: What Your Body…

Vitamins and minerals are the building blocks of human health. These micronutrients power every cellular process in your body — from energy production to immune defense to brain function. Yet despite their importance, many people have significant gaps in their nutritional intake. This guide breaks down every essential vitamin and mineral, what it does, how much you need, and where to find it.

Why Micronutrients Matter

Your body needs 13 essential vitamins and at least 15 essential minerals to function properly. Unlike macronutrients (proteins, fats, and carbohydrates), your body only needs these in small amounts — but the consequences of deficiency can be severe. Chronic low intake of even a single micronutrient can lead to fatigue, weakened immunity, cognitive decline, and long-term disease risk.

The challenge is that modern food processing, soil depletion, and dietary restrictions have made it harder than ever to get adequate micronutrients from food alone. Understanding what you need and where to get it is the first step toward optimal health.

Fat-Soluble Vitamins (A, D, E, K)

Fat-soluble vitamins are stored in your body’s fatty tissue and liver. They’re absorbed alongside dietary fat and can be stored for long periods, meaning you don’t need them every day — but you do need them regularly.

Vitamin A

Function: Supports vision, immune function, skin health, and cellular communication.

RDA: 900 mcg (men), 700 mcg (women)

Food sources: Liver, sweet potatoes, carrots, spinach, kale, eggs, dairy

Deficiency signs: Night blindness, dry skin, frequent infections, stunted growth in children

Vitamin D

Function: Calcium absorption, bone health, immune regulation, mood support, inflammation reduction.

RDA: 600 IU (15 mcg) for adults, 800 IU (20 mcg) for 70+ years

Food sources: Fatty fish (salmon, mackerel, sardines), egg yolks, fortified dairy, mushrooms exposed to UV light, sunlight exposure

Deficiency signs: Bone pain, muscle weakness, frequent illness, fatigue, depression, hair loss

Vitamin D deficiency is one of the most common nutritional gaps worldwide. An estimated 1 billion people have insufficient levels. If you live in a northern latitude, have darker skin, or spend most of your time indoors, you’re at higher risk. A simple blood test (25-hydroxy vitamin D) can check your levels.

Vitamin E

Function: Powerful antioxidant protecting cell membranes from oxidative damage, supports immune function.

RDA: 15 mg (22.4 IU) for adults

Food sources: Sunflower seeds, almonds, spinach, avocados, olive oil, wheat germ

Deficiency signs: Nerve pain, muscle weakness, vision problems, immune dysfunction (rare but possible with fat absorption disorders)

Vitamin K

Function: Blood clotting, bone metabolism, cardiovascular health.

RDA: 120 mcg (men), 90 mcg (women)

Food sources: Kale, spinach, Brussels sprouts, broccoli, fermented foods (natto), parsley

Deficiency signs: Easy bruising, excessive bleeding, weakened bones (rare in healthy adults)

Water-Soluble Vitamins (B-complex and C)

Water-soluble vitamins aren’t stored in the body long-term. Excess amounts are excreted in urine, so you need a consistent daily intake.

B Vitamins — The Energy Complex

The eight B vitamins work synergistically to convert food into energy, support nervous system function, and produce red blood cells.

• B1 (Thiamine): Energy metabolism, nerve function. Found in pork, sunflower seeds, whole grains. RDA: 1.2 mg (men), 1.1 mg (women).
• B2 (Riboflavin): Energy production, skin and eye health. Found in dairy, eggs, almonds, spinach. RDA: 1.3 mg (men), 1.1 mg (women).
• B3 (Niacin): DNA repair, cholesterol regulation, brain function. Found in chicken, turkey, peanuts, mushrooms. RDA: 16 mg (men), 14 mg (women).
• B5 (Pantothenic Acid): Hormone and neurotransmitter synthesis. Found in liver, mushrooms, avocados, eggs. RDA: 5 mg.
• B6 (Pyridoxine): Brain development, neurotransmitter production, mood regulation. Found in chicken, bananas, potatoes, chickpeas. RDA: 1.3-1.7 mg.
• B7 (Biotin): Hair, skin, and nail health, metabolism. Found in eggs, nuts, seeds, sweet potatoes. RDA: 30 mcg.
• B9 (Folate): DNA synthesis, fetal development, mood support. Found in leafy greens, lentils, beans, asparagus. RDA: 400 mcg.
• B12 (Cobalamin): Nerve function, red blood cell formation, DNA synthesis. Found in animal products only — meat, fish, dairy, eggs. RDA: 2.4 mcg. Vegans and vegetarians are at high risk of deficiency and should supplement.

Vitamin C

Function: Antioxidant, collagen synthesis, immune support, iron absorption enhancer.

RDA: 90 mg (men), 75 mg (women); smokers need 35 mg more

Food sources: Citrus fruits, bell peppers, strawberries, kiwi, broccoli, Brussels sprouts

Deficiency signs: Scurvy (severe), bleeding gums, slow wound healing, frequent infections, fatigue

Essential Minerals

Calcium

Function: Bone and teeth structure, muscle contraction, nerve signaling, blood clotting.

RDA: 1,000 mg (19-50 years), 1,200 mg (51+ years and postmenopausal women)

Food sources: Dairy, sardines with bones, kale, bok choy, fortified plant milks, sesame seeds, almonds

Deficiency signs: Osteoporosis, muscle cramps, brittle nails, dental problems

Iron

Function: Oxygen transport via hemoglobin, energy production, immune function.

RDA: 8 mg (men), 18 mg (women 19-50), 8 mg (women 51+)

Food sources: Red meat, liver, oysters, lentils, spinach, pumpkin seeds, fortified cereals. Pair with vitamin C for better absorption.

Deficiency signs: Fatigue, pale skin, shortness of breath, cold hands/feet, brittle nails, restless leg syndrome. Iron deficiency is the most common nutritional deficiency worldwide, affecting over 25% of the global population.

Magnesium

Function: 300+ enzymatic reactions, muscle and nerve function, blood pressure regulation, blood sugar control, sleep quality.

RDA: 400-420 mg (men), 310-320 mg (women)

Food sources: Pumpkin seeds, spinach, dark chocolate, almonds, black beans, avocados, whole grains

Deficiency signs: Muscle cramps, insomnia, anxiety, fatigue, migraines, high blood pressure. Up to 50% of adults may have suboptimal magnesium intake.

Zinc

Function: Immune function, wound healing, protein synthesis, DNA synthesis, taste and smell.

RDA: 11 mg (men), 8 mg (women)

Food sources: Oysters (highest source), beef, pumpkin seeds, lentils, chickpeas, cashews

Deficiency signs: Frequent infections, slow wound healing, hair loss, loss of taste/smell, acne

Selenium

Function: Antioxidant defense, thyroid function, immune support.

RDA: 55 mcg for adults

Food sources: Brazil nuts (just 1-2 per day provides the RDA), fish, eggs, sunflower seeds, mushrooms

Deficiency signs: Weakened immunity, hair loss, fatigue, brain fog (rare but possible in regions with selenium-poor soil)

Potassium

Function: Fluid balance, nerve signaling, muscle contractions, blood pressure regulation.

RDA: 3,400 mg (men), 2,600 mg (women)

Food sources: Bananas, potatoes, sweet potatoes, avocados, spinach, beans, coconut water

Deficiency signs: Muscle weakness, cramps, irregular heartbeat, fatigue, high blood pressure

How to Assess Your Nutritional Status

The most reliable way to know if you have deficiencies is through blood testing. Key tests to consider:

• Complete blood count (CBC) — detects iron, B12, and folate issues
• Ferritin — true iron stores (more accurate than hemoglobin alone)
• 25-hydroxy vitamin D — vitamin D status
• RBC magnesium — intracellular magnesium (more accurate than serum)
• Comprehensive metabolic panel — calcium, potassium, sodium
• Homocysteine — indirect marker of B6, B12, and folate status

Food First, Supplements Second

The best source of vitamins and minerals is always a varied, whole-food diet. Supplements should fill gaps, not replace good nutrition. Focus on eating the rainbow — different colored fruits and vegetables provide different phytonutrients and micronutrients. Include a variety of protein sources, healthy fats, and whole grains.

If you do supplement, be strategic. Common beneficial supplements for most adults include vitamin D (especially in winter), magnesium, omega-3 fatty acids, and B12 (for vegans/vegetarians). Always consult with a healthcare provider before starting any supplement regimen, as some vitamins and minerals can interact with medications or have toxicity risks at high doses.

The Bottom Line

Understanding your micronutrient needs is foundational to long-term health. By eating a diverse, nutrient-dense diet and strategically supplementing where needed, you can prevent deficiencies and support optimal function across every system in your body. Start with food, test your levels, and supplement wisely.