The Water-

Soluble

Vitamins: Intro

Chapter 10

2018

The Vitamins – An Overview

Support nutritional health

Vitamins differ from macronutrients

Structure

Individual units

Function

No energy yielded

Food contents

Similarities to macronutrient

The Vitamins – An Overview

Bioavailability

Quantity provided by food

Amount absorbed and used by body

Factors influencing bioavailability

Efficiency of digestion

Nutrition status

Method of food preparation

Source of nutrient

Other foods consumed at same time

The Vitamins – An Overview

Precursors

Provitamins

Converted to active form in body

Organic nature

Can be destroyed during storage and in

cooking

The Vitamins – An Overview

Solubility

Affects absorption, transport, and excretion

Water-soluble

Move directly into blood

Most travel freely

Fat-soluble

Enter lymph and then blood

Require transport proteins

Consumption frequency of vitamins

The Vitamins – An Overview

Toxicity

More is not necessarily better

Excessive intakes

Levels higher than UL

The Vitamins – An Overview

The B Vitamins – As Individuals

Vitamins do not provide the body with

fuel for energy

Coenzymes

Assist enzymes with release of energy

Without coenzyme, an enzyme cannot

function

The B Vitamins – As Individuals

Vitamin-Like Compounds

Inositol

Part of cell membrane structures

Carnitine

Transports long-chain fatty acids for

oxidation

Both can be made by body

No recommendations established

Both are widespread in foods

The B Vitamins – In Concert

Each B vitamin coenzyme is involved in

energy metabolism

Directly

Indirectly

Deficiencies

Single B-vitamin deficiencies seldom show

up in isolation

Beriberi and pellagra

The B Vitamins – In Concert

The B Vitamins – In Concert

Toxicities

Excess eliminated through urine excretion

Homeostasis disruption

Toxicities develop

Food sources

First choice should be foods rather than

supplements