Vitamins: Introduction & Definitions

Question 1

Introduction

Answer 1

Biochemist Casimir Funk coined the term vitamin in 1911
* He discovered ‘beriberi’, which causes mostly neurological symptoms and mostly affects those on a diet of white rice. Funk identified that the cause was a lack of thiamine (vitamin B1)
* Thiamine was named to reflect the belief that all vitamins contains nitrogen (amines). However, it was later discovered that not all vitamins contain nitrogen. ‘Vitamine’ was changed to ‘vitamin’ (no e).
* Different chemical forms of each vitamin exist, these are called ‘vitamers’. Vitamers are generally similar in structure.
* For example, a person who is vitamin B3 deficient could be relieved by either of the B3 vitamers: Niacinamide or nicotinic acid

Question 2

Vitamins

Answer 2

There are 13 vitamins – A, C, D, E, K and the B vitamins (thiamine, riboflavin, niacin, pantothenic acid, biotin, B6, B12, and folate)

Question 3

Vitamin functions

Answer 3

Key functions of vitamins include:
* Supporting the immune system
* Regulating gene expression
* Supporting neurological activity
* Facilitating ATP production
* Manufacturing of blood cells
* Regulation of hormones

Question 4

Vitamin absorption

Answer 4

Vitamins are absorbed in the small intestine. It is, therefore, vital to optimise GIT health.

Question 5

Essential nutrients

Answer 5

Vitamins are carbon-containing compounds that are essential to the body in small amounts for normal growth and function

• The body cannot produce vitamins (with the exception of vitamin D)
• Vitamin this cannot be directly converted into energy or tissues, like macronutrients can. However:
  o Some vitamins are essential in the process of energy production (B1, B2, B3, B5). If deficient, this can result in poor ATP production, e.g. vitamin B5 is needed for the synthesis of coenzyme A (review Biochemistry)
  o Vitamins facilitate physiological functions in the body, e.g. Vitamin C facilitates collagen synthesis (but is not a physical part of collagen)

Question 6

Co-factors

Answer 6

Vitamins do not occur in isolation in nature. Therefore, be mindful that supplements do not offer the same therapeutic advantages as consuming a spectrum of nutrients via food.
* Vitamins (as they occur in food) are relatively ‘inert’ until the body activates them
Vitamin-dependent enzymes:
* Vitamins are required for the activation of vitamin-dependent enzymes (They hence function as co-factors)
* Four example, B vitamins are vital co-factors for the action of the CYP450 enzymes system, needed the phase 1 liver detoxification. Therefore, B vitamins can be used as part of a liver support program
Co-factor = an essential component for enzyme activity

Question 7

Classification

Answer 7

There are two types of vitamins: Fat- and Water- soluble
1. Fat soluble vitamins: A, D, E, K
* Fat soluble vitamins are soluble in fats
* Absorbed with fat in the small intestine into the lymphatic capillaries and then into the blood. They are readily stored
* Tighter range between efficacy and toxicity than water soluble
2. Water soluble vitamins: B vitamins and vitamin C
* Water soluble vitamins are soluble in water
* Absorbed in the small intestine directly into the blood. Storage is minimal (exception = B12), and easily excreted, if excess

Question 8

Insufficiency to Deficiency

Answer 8

Progression of insufficiency to deficiency of vitamins:
1. Preliminary reduction of stores
2. Reduction in enzyme activity
3. Physiological impairment (early signs and symptoms)
4. Classical deficiency syndromes
5. Terminal tissue pathway
True vitamin deficiencies are rare (except for vitamin B12 and vitamin D). Most cases in clinic are insufficiently states

Insufficiency = subclinical deficiency (i.e. vague symptoms)
Deficiency = clinical signs and symptoms of deficiency