8. VITAMINS Flashcards
This module covers: • Specific characteristics of vitamins A, C, D, E, K and the B vitamins. • Dietary sources, bioavailability and interactions. • Functions, deficiency states, therapeutic uses and safety considerations. • Dosage levels and preferred forms for micronutrients.
What are vitamins? How does the word vitamin break down and who coined the term?
Vitamins are carbon-containing compounds that are essential to the body in small amounts for normal growth and function.
“Vita” = life
“Amine” = contains nitrogen
Biochemist Casimir Funk
What led biochemist Casimir Funk to the discovery of vitamins?
He discovered ‘beriberi’, which causes mostly neurological symptoms such as numbness and mostly affects those on a diet of white rice. Funk identified that the cause was a lack of thiamine (vitamin B1).
Complete:
It was once thought that all vitamins contained (________). However, it was later discovered that this was not the case, and ‘vitamine’ was changed to ‘vitamin’.
nitrogen (amines)
Different chemical forms of each vitamin exist, these are called _____ and are generally similar in structure.
vitamers
How many vitamins are there?
Name them indicating which of the 2 categories they belong to?
There are 13 vitamins
Fat-soluble - vitamins A, D, E, K.
Water Soluble - vitamin C and the B vitamins (thiamine, riboflavin, niacin, pantothenic acid, biotin, B6, B12, and folate).
What does fat soluble mean in terms of vitamins?
Where are water-soluble vitamins absorbed?
Fat soluble: Absorbed with fat in the small intestine into lymphatic capillaries and then into the blood. These vitamins are readily stored.
Water-soluble vitamins are absorbed in the small intestine directly into the blood. Storage is minimal (exception = B12), and easily excreted, if in excess.
What are the key functions of vitamins and where are they absorbed?
- Supporting the immune system.
- Regulating gene expression.
- Supporting neurological activity.
- Facilitating ATP production.
- Manufacturing of blood cells.
- Regulation of hormones.
They are mainly absorbed in the small intestine
The body cannot produce vitamins with the exception of which one?
Vitamin D
Which vitamins are essential in the process of energy production?
If there is a deficiency of these vitamins this can result in poor ___ production
B1, B2, B3, B5
ATP
Give an example of a vitamin which facilitates physiological functions in the body but is not a physical part of the end result
Vitamin C facilitates collagen synthesis but is not a physical part of collagen
What is a co-factor?
An essential component for enzyme activity
Vitamins do not occur in isolation in nature. How could this impact our view of supplements?
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. How are they activated?
Give an example of a co-factor needed for the action of the CYP450 enzyme system needed for phase 1 liver detoxification
With co-factors
B-vitamins. Therefore, B vitamins can be used as part of a liver support programme
Define insufficiency
Sub-clinical deficiency (i.e., vague symptoms)
Define deficiency
deficiency greater than insufficiency in amount of something needed
List the five stages 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 pathology.
True vitamin deficiencies are rare with the exception of which two vitamins?
Vitamin B12 and vitamin D.
Most cases in clinics are insufficiency states
Which was the first vitamin to be discovered?
Vitamin A
What are the active forms (vitamers) which execute the functions of vitamin A?
Depending upon what the body requires, retinol will be oxidised to the different forms. What are these forms?
Retinol, retinal and retinoic acid.
retinol →retinal →retinoic acid
What happens if the body doesn’t need vitamin A at the time it is consumed?
It will remain as retinol and be stored in the liver.
All forms of vitamin A work on different body parts, on which part of the body does the following work:
1) Retinol
2) Retinal
3) Retinoic Acid
1) Health of the Retina
2) Vision, visual pigments of rod & cone cells of retina
3) Growth & differentiation of epithelial cells
What are the two forms of vitamin A?
Pro-vitamin A & Pre-formed vitamin A (Retinol)
Where does the Greek word carotene come from?
Karoton for ‘carrot’ — orange pigments
Where is Pro-vitamin A converted into the active (usable) form of vitamin A (retinol)?
In the small intestinal epithelium and liver.
How does pro-vitamins differ from pre-formed vitamins?
Pro- A substance that can be converted into a vitamin
Pre- A vitamin that is already formed
Where can pro-vitamin A be found? And what are the most active types?
Carotenes (or carotenoids) are examples of pro-vitamin A.
The most active pro-vitamin carotenes are: α-(alpha), β-(beta) and γ-(gamma) carotenes and cryptoxanthin.
Are there toxicity concerns with dietary carotenes?
Dietary carotenes are converted to vitamin A only as needed, so there are no toxicity concerns.
There is a great deal of variability of the absorption rates of carotenoids, where are they absorbed and at what rate?
How could you increase absorption of carotenoids?
The absorption of carotenoids in the small intestine varies between 5% and 60%.
As carotenoids are fat-soluble. Drizzle with coconut oil or olive oil to optimise absorption.
What is the most effective way to liberate carotenoids from food?
A way to increase the bioavailability of carotenoids is to cook (slightly steam) these foods, e.g., carrots. This cooking method is thought to most effectively liberate carotenoids from cells.
Where can pre-formed vitamin A be found?
Only in animal foods and can be used as it is.
Pro-vitamin A is produced by plants. Name some rich sources of where it can be found?
Algae, fungi and bacteria. Rich food sources: Dark green, yellow / orange vegetables and fruit, e.g., carrots, squash, mango, spinach, sweet potatoes.
Pre-formed-vitamin A is found in animal foods. Name some examples of where it can be found?
liver, fish liver oils, egg yolk, mackerel, salmon.
Which enzyme converts carotenoids to retinal in the intestinal epithelium and liver is encoded by which gene?
BCO1 gene
Which conditions can reduce carotene conversion?
Hyperlipidaemia, liver disorders, diabetes and hypothyroidism
What can excessive intake of carotenoids lead to? And what could it be mistaken for?
What could a sallow yellow complexion (i.e., pale or pasty), especially in the face indicate according to TCM?
A non-dangerous yellowing of the skin. However, yellowing of the skin might also be associated with disorders of the liver, gallbladder.
A Spleen Qi deficiency. In TCM, this refers to ‘weakness’ in digestion function.
What is the absorption rate of pre-formed vitamin A?
What is the recommended dosage for pre-formed vitamin A?
About 70–90% of dietary retinol is absorbed ―this is a key reason that animal food sources of vitamin A can lead to vitamin A toxicity (liver particularly).
Supplemental range: Adults maximum 3000 mcg (micrograms) preformed A. Higher doses are appropriate in some situations but should only be used short-term.
Why is it best to avoid isolated beta-carotene supplementation?
It is recommended to avoid isolated beta-carotene supplementation, as it was shown to worsen the progression of lung cancer patients in a research study (recall that antioxidants do not work in isolation).
As carotenes (provitamin A) don’t have the same vitamin A activity as preformed vitamin A a method has been invented in order to show the real retinal potency of a given carotenoid in supplemental form. What is it called?
The amounts of vitamin A are expressed as mcg of retinol activity equivalents (RAE)
What is the conversion ratio of beta-carotene in food to retinol?
What is the conversion ratio of beta-carotene in supplements to retinol?
1 RAE = 1 mcg of retinol = 12 mcg of beta-carotene = 24 mcg of alpha-carotene or beta-cryptoxanthin from dietary sources.
Supplements conversion is: 2mcg beta-carotene = 1mcg retinol.
What is the meaning of the word rhodopsin?
The visual purple
Vitamin A is required for vision and eye health. What are two functions that it is required for?
Required for rhodopsin ― the light-sensitive protein involved in converting light into an electrical signal that goes into the brain’s visual cortex, giving the message of sight.
It is also necessary for corneal health.
Name four therapeutic uses of Vitamin A with regard to vision and eye health
*Photosensitivity
*Visual loss
*Night-blindness
*Senile cataracts
Vitamin A is required for immunity. What are two functions that it is required for?
*Enhances T-cell proliferation and interleukin-2 secretion.
*Supports first line of immune defence (skin and mucous membrane barrier).
Name a therapeutic use of Vitamin A with regard to immunity?
Recurrent infections, e.g., respiratory tract infections.
Vitamin A is required for gene expression and cell differentiation. What are three functions that it is required for?
*Control of cell differentiation and turnover. Regulating the expression of over 500 genes, affecting the synthesis of proteins that regulate cell functioning.
*Key as a preventive measure to support healthy gene expression.
*Synthesis of glycoproteins which support normal development of bones, teeth and skin.
Name some therapeutic uses of Vitamin A with regard to cell differentiation and gene expression.
*Acne
*Anaemia
*Cervical dysplasia
*Hair loss in women
*Fracture repair
*Lichen planus
*Osteoarthritis
*GIT ulceration
*Vaginitis
*Periodontal disease
Vitamin A is required for reproduction. What are three functions that it is required for?
*Reproductive & embryonic health.
*Required for spermatogenesis in men.
*Required for egg (ovum) development and implantation.
Vitamin A is required for it’s antioxidant properties. What are two functions that it is required for?
*Preformed and provitamin A have antioxidant properties.
*The foods rich in carotenoids are also rich in other antioxidants, again highlighting that they don’t work in isolation.
Name some therapeutic uses of Vitamin A with regard to reproduction?
“*Infertility (male and female)
*Fibrocystic breast disease
Name some therapeutic uses of Vitamin A with regard to antioxidant properties?
“*Used in various therapies, including carrot juicing for cancer (Gerson therapy).
*Disease prevention
Describe how to make carrot/apple juice as used in the Gerson therapy?
*Approx. 3 large carrots: 1 large green apple (8–12 oz each).
*Use only organic produce and a cold-press juicer.
*Use sour apples such as Granny Smith (these are higher in malic acid and pectin which support heavy metal chelation, and also extract more nutrients from the carrots / apple).
*Wash and brush the carrots; cut off the ends. Do not peel.
*Wash the apples, cut them and remove the stem / seeds.
*Consume as soon as possible to stop the juice oxidising.
What is hyperkeratosis?
thickening of the stratum corneum (‘goose flesh’)
What should you consider doing before supplementing with vitamin A?
Add 1-2 portions of beta-carotene rich foods a day
Name six signs and symptoms of vitamin A deficiency?
*Vision impairment at night is an early sign: Loss of sensitivity to green light, unable to adapt to dim light and night blindness. Prolonged deficiency can lead to blindness.
*Hyperkeratosis of skin of upper arms.
*Reduced skin integrity —rough dry skin, acne, eczema, poor wound healing. Dry hair.
*Poor bone growth / development.
*Poor sense of taste and smell.
*Lowered immunity (recurrent infections).
Which pathologies reduce carotene conversion?
Diabetes mellitus, thyroid, and liver disease
How does alcoholism affect vitamin A?
Accelerates the breakdown of liver-stored retinol; absorption and carotene conversion is reduced. Increased vitamin A toxicity potential; not supplemented with preformed A.
How does poor gut health affect vitamin A?
Name a condition which could be implicated.
Name a drug which may affect it.
Poor gut health (lack of absorption in small intestine) and conditions that affect fat absorption, e.g., cystic fibrosis,
statins
How would zinc deficiency or protein malnutrition affect vitamin A?
Zinc and protein are required to make Retinol Binding Protein (RBP). RBP moves vitamin A from liver storage to tissues for utilisation. Without zinc, vitamin A is trapped. So optimise intake of zinc-rich foods.
What is a hepatocyte?
liver cell
How long it take to reach vitamin A toxicity?
How can vitamin A toxicity affect the following:
Embroylogical development?
Bone health?
Liver health?
Skin health?
Long-term and regular intake -roughly 5–10 times the recommended nutrient intake over many months
Can negatively affect gene regulation during embryological development leading to birth defects (e.g., cleft lip).
May increase osteoclast activity and lead to bone fractures.
Can damage hepatocyte cell membranes (causing liver disease).
Can cause dry, red and scaling skin
What conditions could vitamin A toxicity cause?
Name a vitamin A drug interaction?
Can lead to hyperlipidaemia, amenorrhea and anorexia.
warfarin, as it decreases vitamin K absorption (increasing bleeding risk).
Technically vitamin D is not strictly a vitamin, why is this?
What does the word ergocalciferol mean?
Vitamin D is not strictly a vitamin since it can be synthesised in the skin in response to sunlight.
‘ergo’ = plant sourced D
‘chole’ = animal sourced D
Why would you require dietary sources of vitamin D?
Name two dietary sources of vitamin D and list types and example
Dietary sources are only required in the absence of adequate sunlight (UVB)
Plant source: Vitamin D2 (ergocalciferol D2) — found in mushrooms (fungi), but these require good sun exposure.
– Animal source: Vitamin D3 is 7-dehydroxycholesterol (cholecalciferol D3) — found in cod liver oil, oily fish (herring,
mackerel, sardines, wild-caught salmon) and organic egg yolks.
What functions do vitamin D2 and D3 have?
In which organs are vitamin D2 and D3 activated?
Vitamin D2 and D3 do not have any direct functions they both first need to be converted (hydroxylated).
Liver and kidney
At what range does conventional medicine consider serum ranges (of calcidiol) to be sufficient?
At what range does conventional medicine consider serum ranges (of calcidiol) to be deficient?
At what range does naturopathic medicine consider serum ranges (of calcidiol) to be sufficient or optimal?
over 50 nmol / L
Below 25 nmol / L is almost universally agreed to be deficient.
The optimal range is generally considered to be 75–125 nmol / L (some variance). So are your clients’ levels ‘sufficient’ or ‘optimal’?
What is 1,25-Calcitriol?
The active form of vitamin D
What is the meaning of the term endogenous?
from within the body
If you’re outside how long does your shadow need to be in order to get enough sunlight to make vitamin D?
When are serum levels of vitamin D usually the highest and lowest?
The same height or shorter that you
Serum levels are usually highest at the end of the summer and lowest at the end of winter.
What can block the conversion of vitamin D?
Sunscreens and window glass block the conversion to vitamin D by blocking UVB radiation.
How long can vitamin D be stored in the liver?
vitamin D can be stored in the liver for 4 months.
How long does it take to produce 400IU of vitamin D in fairer skin types?
And what is the difference to make the same amount with a darker skin tone?
What does μg stand for?
10 minutes of summer sun exposure results in endogenous production of about 400IU in fairer skin types. In darker skin tones it can take 3–6 times longer to produce the same amount of D3.
Microgram
Regarding vitamin D.
What should our focus be when coming across a deficiency to avoid a symptom based approach?
What supplemental dose can be used without adverse effects?
How often should vitamin D levels be tested?
What dosage of vitamin D would be recommended in the case of a pronounced deficiency: (<10 ng / mL)?
first address the cause of the deficiency
A supplemental dose of 4000 IU / day has been used without adverse effects. 1 μg of cholecalciferol = 40 IU.
It is advisable to test vitamin D levels every four months to adjust dosing where appropriate.
50,000 IU of vitamin D3 orally once weekly for 2–3 months, or 3 times weekly for 1 month.
Regarding supplementation: why is D3 preferred above ergocalciferol?
Ergocalciferol is less than one-third as potent as cholecalciferol, so D3 is favoured for supplementation. D3 supplements also stay in circulation longer.
What is a key function of vitamin D in the body?
A key function of vitamin D is to maintain serum calcium and phosphorus homeostasis.
