Nutrition · A Holistic View of Micronutrients

Vitamins

Safety note: Educational content only. No doses, supplement recommendations, laboratory ranges, or deficiency treatments are provided; diagnosis and therapy require clinical evaluation, the care team, pharmacy, and RD. Flag for source/SME review before clinical use.

On this page 10 sections

In 30 seconds
Why this matters
The college version
Eli explains
Worked example
Key takeaway
Check yourself
Quick check
Study tools
Sources & references

In 30 seconds

Vitamins are organic compounds the body needs in tiny amounts to run its chemistry. They are micronutrients — measured in milligrams or micrograms, not grams — and provide no energy themselves. Instead, many work as coenzymes, helper molecules enzymes need to do their jobs: thiamin helps unlock energy from carbohydrate, folate helps build DNA for new cells, and K helps activate clotting factors.

The body cannot make most vitamins in adequate amounts, so they must come from food. The organizing principle is solubility: water-soluble vitamins (the B complex and vitamin C) are absorbed with water, not stored in large amounts, and are lost in urine — so regular intake matters and cooking can destroy them. Fat-soluble vitamins (A, D, E, K) are absorbed with dietary fat, stored in the liver and adipose tissue, and can accumulate — so excess can be harmful. This distinction explains who is at risk of , who is at risk of , and what to teach.

Why this matters

Deficiencies are preventable — when recognized. Classic deficiency diseases (scurvy with vitamin C, rickets with vitamin D, pellagra with niacin) still occur; nurses who recognize risk factors can raise the right concerns.
Risk groups are common in nursing: people with restrictive diets, alcohol use disorder (thiamin, folate), older adults with reduced absorption (B12), vegans (B12), people with fat malabsorption (A, D, E, K), and people after bariatric or gastrointestinal surgery.
Medication interactions are real: vitamin K interacts with anticoagulant therapy, and long-term use of certain medications can affect B12 and folate status. Nurses flag concerns and defer to pharmacy and the care team.
Supplements are medicines in disguise: patients take vitamins daily, often without mentioning them; asking about supplements is part of medication reconciliation.
Cooking and pregnancy: boiling vegetables leaches water-soluble vitamins; folate and B12 are linked to normal cell division and neural tube development, making prenatal vitamin recommendations standard care.

The college version

Core Concepts

Water-soluble vitamins: the B complex and vitamin C

Water-soluble vitamins absorb directly into the blood and circulate freely; the body holds only small reserves (B12 is the exception, with a large liver store), and excess is excreted in urine. Regular intake is needed, food-source toxicity is rare, and cooking losses matter.

Thiamin (B1): helps convert carbohydrate into energy; deficiency is classically associated with beriberi and with Wernicke–Korsakoff syndrome in alcohol use disorder. Enrichment restores it in many countries.
Riboflavin (B2) and B6 (pyridoxine): support energy and amino acid metabolism; found in dairy, eggs, vegetables, and whole grains.
Niacin (B3): part of NAD/NADH, central to energy metabolism; deficiency historically caused pellagra in corn-heavy diets. Large supplement doses can cause flushing — a teaching point, not a recommendation.
Folate (B9): needed for DNA synthesis and cell division; the synthetic form (folic acid) is used in supplements and fortified foods. Adequate folate before and early in pregnancy is linked to normal neural tube development; low folate can contribute to megaloblastic anemia.
B12 (cobalamin): needed for red blood cell formation and nerve function; absorption requires from the stomach, so older adults, people after gastric surgery, and some with autoimmune conditions can develop deficiency despite adequate intake (pernicious anemia concept). Vegans rely on fortified foods or supplements because natural B12 comes mainly from animal foods.
Vitamin C (ascorbic acid): needed for collagen synthesis (wound healing), enhances iron absorption from plant foods, and acts as an antioxidant; deficiency causes scurvy.

Fat-soluble vitamins: A, D, E, K

Fat-soluble vitamins are absorbed into chylomicrons along with dietary fat and stored — A and D largely in the liver, E in tissues, K in smaller amounts. Because they are stored, excess accumulates: toxicity from very high supplement doses is possible, especially for A and D.

Vitamin A (retinol/carotenoids): supports vision (especially low-light), epithelial health, and immune function; sources include liver, dairy, and orange/red vegetables (beta-carotene, a the body converts). Deficiency impairs night vision; excess from supplements, not food, can be harmful.
Vitamin D: unique in that skin can make it with sunlight; it regulates calcium and phosphorus handling and supports bone health. Deficiency is linked to rickets in children and osteomalacia in adults — population-level associations; screening and treatment are clinical decisions.
Vitamin E (tocopherols): antioxidant family protecting cell membranes; found in nuts, seeds, and vegetable oils.
Vitamin K: needed to activate clotting factors and bone proteins; made partly by gut bacteria and found in green leafy vegetables. Changes in vitamin K intake can interact with anticoagulant medications — a classic interaction nurses flag for pharmacy review.

Bioavailability: food content ≠ absorbed amount

— how much of a vitamin in food is actually absorbed — depends on food processing and cooking (heat and water destroy water-soluble vitamins; steaming preserves more), gut health (celiac disease, Crohn's disease, bariatric surgery, and bowel resection reduce absorption), age and stomach acid (B12 absorption declines with reduced acid and intrinsic factor), and dietary companions (fat-soluble vitamins need fat; vitamin C improves iron absorption; some minerals compete — see Minerals).

The nurse's takeaway: a food containing a vitamin is not the same as the body receiving it — risk groups need assessment and referral, not guesswork.

Deficiency and toxicity: two ends of one continuum

Vitamins sit on a continuum: too little causes deficiency, too much (mainly via supplements) can cause toxicity, and the healthy range in between is where food patterns normally land. Deficiency risk rises with poor intake, malabsorption, increased need (growth, pregnancy, illness), and increased losses; toxicity risk comes mainly from high-dose supplements, not food. Neither state is diagnosed by appearance; both require clinical evaluation, laboratory testing, and professional interpretation. Nurses recognize risk, ask about supplements, and refer.

Common Confusions

Do not confuse	With	Difference
Water-soluble vitamins	Fat-soluble vitamins	Storage, absorption, and toxicity risk differ completely
Taking vitamins	Getting energy from vitamins	Vitamins provide no energy; they help release it from food
"Natural" supplement	Safe supplement	Natural ≠ risk-free; high doses can still be toxic
More vitamins	Better health	Excess (especially fat-soluble) can be harmful; needs are small
Deficiency signs	A diagnosis	Signs overlap with many conditions; diagnosis requires clinical evaluation
Vitamin K in diet	Safe to change freely on anticoagulants	Consistency matters; changes interact with therapy — pharmacy/care team decide

Eli explains

The same idea, in plain words

Explain it like I’m 10

Vitamins are like tiny tools your body's workers need to build things. Water-soluble vitamins are like pencils and paper — they wash away easily, so you need fresh ones every day, and cooking can ruin them. Fat-soluble vitamins are like hammers and saws — your body stores them in a toolbox, so you don't need them every day, but if you keep buying more and more, the toolbox overflows and that can cause problems.

Worked example

Mr. Okafor, 71, is admitted after a fall. During medication reconciliation, the nurse asks: "Do you take any vitamins, supplements, or herbal products?" He mentions a daily high-dose vitamin A supplement a friend recommended "for eye health," plus a blood-thinning medication for a heart condition.

Ask, don't assume. The supplement question is part of every reconciliation — patients rarely volunteer this information.
Connect to the framework. The nurse recognizes that (a) fat-soluble vitamins like A are stored, so high-dose supplements carry toxicity risk — a flag for the care team; and (b) vitamin K interacts with anticoagulants, so any vitamin K changes are worth flagging to pharmacy.
Refer, don't prescribe. She documents the supplement and notifies the care team and pharmacy; any change to his regimen requires provider and pharmacist input.
Teach the general concept. She explains that vitamin needs are usually met through food and more is not automatically better, with an RD consult offered.

The lesson: vitamins belong in the medication conversation, and the nurse's job is to surface, document, and refer — never to advise doses.

Key takeaways

Vitamins are organic micronutrients that provide no energy; most act as coenzymes.
Water-soluble (B complex + C): minimal storage (B12 is the exception), excreted in urine, destroyed by cooking — regular intake required.
Fat-soluble (A, D, E, K): absorbed with dietary fat, stored in liver/adipose, can accumulate — excess supplements can be toxic.
Classic deficiency concepts: thiamin (alcohol use disorder), niacin (pellagra), C (scurvy), D (rickets/osteomalacia), B12 (pernicious anemia concept; vegans at risk), folate (cell division; prenatal focus).
B12 absorption requires intrinsic factor; aging and gastric changes raise deficiency risk.
Vitamin K interacts with anticoagulant therapy — changes in intake matter; flag for pharmacy/care team.
Nurses: ask about supplements at medication reconciliation, recognize risk groups, and refer to RD/pharmacy/care team — no doses or treatment recommendations.

Check yourself

5 review questions from the chapter. Try each one, then open the answer.

What is the organizing principle separating water-soluble from fat-soluble vitamins, and why does it matter for deficiency risk?
Show answer
Solubility: water-soluble vitamins dissolve in water, are minimally stored, and are lost in urine (regular intake needed); fat-soluble vitamins dissolve in fat, are stored, and can accumulate (excess risk).
Name the water-soluble vitamins as a group and the fat-soluble vitamins as a group.
Show answer
Water-soluble: the B complex (thiamin, riboflavin, niacin, B6, folate, B12, plus biotin and pantothenic acid) and vitamin C. Fat-soluble: vitamins A, D, E, and K.
Why can a person eat plenty of B12-containing food and still develop B12 deficiency?
Show answer
B12 absorption requires stomach acid and intrinsic factor; aging, gastric surgery, and some autoimmune conditions reduce absorption, so food intake alone may not prevent deficiency.
A patient on an anticoagulant suddenly increases green leafy vegetables. What is the concern, and what should the nurse do?
Show answer
Vitamin K participates in clotting and can interact with anticoagulant therapy; a sudden intake increase may affect the medication's action. The nurse flags the change for the care team and pharmacy — she does not advise dietary changes herself.
Why should the nurse ask every patient about vitamins and supplements during medication reconciliation?
Show answer
Patients commonly take vitamins and supplements daily without mentioning them; they can interact with medications and affect clinical status, so they belong in the medication list and reconciliation process.