Vitamins Flashcards
What are some of the Key functions of vitamins?
- Supporting the immune system.
- Regulating gene expression (how we make proteins)
- Supporting neurological activity.
- Facilitating ATP production.
- Manufacturing of blood cells.
- Regulation of hormones.
Vitamins do this by enabling enzymatic function. They are required for the activation of vitamin-dependent enzymes (they hence function as ‘co-factors’).
Where are vitamins absorbed?
In the small intestine
What do we mean when we say a vitamin is active?
It means that it is usable and does nto have to go through any more conversion processes before we benefit from it.
For example Pro-Vitamin A must be converetd to Retinol, the active form of Vitamin A, before it can be used.
Name the fat soluble and water soluble vitamins and explain what the difference is between them.
Fat soluble vitamins include A, D, E and K.
* They require fat for absorption.
* readily stored in fatty tissue
* because they are readily stored they are hard to excrete and therefore with supplementation we have a narrow window between efficacy and toxicity
* Absorbed with fat in the small intestine into the lymphatic capillaries and then into the blood
Water soluble vitamins include B and C vitamins.
* Far less likely to be toxic.
* soluble in water
* We excrete them more readily
*We don’t store very much and therefore need a regular intake.
* because we excrete them all readily and don’t store very much there is a broad range between efficacy and toxicity
* absorbed this small intestine
Which vitamins are you most likely to see a deficiency in?
True vitamin deficiencies are rare - except for vitamin B12 and vitamin D.
Most cases in clinic are insufficiency states
The active forms (vitamers) which execute the functions of vitamin A are:
Retinol:
- Health of Retina
- Used to make the other two vitamers: retinol»_space;> retinal»_space;> retinoic acid
- Stored in liver if not needed
Retinal - enables colour vision
Retinoic acid works at DNA level. Growth and differentiation of epithelial cells.
What are the two forms of Vitamin A and where do we find them?
Pro-vitamin A:
- a substance that can be converted into the active form of vitamin A (retinol) in the small intestinal epithelium and liver.
- Comes from a family of phytonutrients called Carotenes (or carotenoids).
- Rich food sources: Dark green, yellow / orange vegetables and fruit, e.g., carrots, squash, mango, spinach, sweet potatoes.
- Found in non-animal foods
Pre-formed vitamin A
- This is active preformed vitamin A the body can use as it is.
– Only found in animal foods as they have done the conversion for us.
- liver, fish, liver oils, egg yolk, mackerel, salmon
- Therefore more bioavailable to the human body.
Active = usable
What influences absoption of pro-vitamin A?
Pre-formed Vitamin A absorbs at a much higher rate (70-90%) than Pro-Vitamin Ain @ (5-60%).
Therefore we do need to be careful about eating too much Preformed Vitamin A in food such as liver.
Bioavalibilty is higher when
* The gut is healthy
* Healthy fats are present. eg: Drizzle with coconut oil or olive oil to optimise absorption
* Caratenoids are lightly cooked (an exception to the usual rule!)
Pro-Vitamin A requires conversion to retinal.
* What is the name of the enzyme involved in this?
* What can reduce the conversion?
What is the name of the enzyme involved in this?
Conversion of Carotenoids to Retinol occurs by way of an enzyme called BCO1gene
What can reduce the conversion?
Genetic variations of the BCO1 gene
Hyperlipidaemia, liver disorders, gut disorders and diabetes and hypothyroidism
What is RAE?
Dosage and Toxicity of Vitamin A.
Are there any drug interactions we shoud be aware of?
RAE
We use a measure called Retinol Activity Equivalent (RAE) to recognise the real retinol potency of a given carotenoid in supplement form.
Dosage
Carotenes such as alpha-carotene and beta-carotene don’t have the same potency as retinol.
Recommended nutrient intake (600-700 mcg a day)
TUL: 3000 mcg for retinol ie: Adults maximum 3000 mcg
Toxicity:
Dietary carotenes are converted to vitamin A only as needed, so do not have toxicity concerns - although it may make you look yellow.
Would need 5-10 times RNI of 600-700 msg a day over many months.
Drug interactions
Warfarin, as it decreases vitamin K absorption (increasing bleeding risk).
List 5 functions of Vitamin A.
(Consider what this means for how you might use it therapuetically)
- Vision and eye health: Night vision and corneal health
- Immunity: Enhances T-cell proliferation and Interleukin 2 secretion, supports integrity of skin and mucous membrane
- Regulating the healthy expression of over 500 genes (The balance of vitamin A and D is essential for proper gene transcription), cell differentiation and turnover, synthesis of glycoproteins which support normal development of bones, teeth and skin.
- Reproduction: Embryonic health, spermatogenesis, ovum development
- Antioxidant Properties
What are the signs and symptoms of deficiency in Vitamin A?
- Vision impairment at night is an early sign and 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.(also closely linked to zinc deficiency)
- Lowered immunity (recurrent infections).
What factors affect individual requirements for Vitamin A?
- Diabetes mellitus, thyroid and liver disease — ↓carotene conversion.
- Alcoholism: Accelerates the breakdown of liver-stored retinol; absorption and carotene conversion is reduced.
- Poor gut health (lack of absorption in small intestine) and conditions that affect fat absorption, e.g., anything to do with GIT organs and supplementary organs, IBD, cystic fibrosis, statins, etc.
- Zinc deficiency and / or protein malnutrition: Zinc and protein are required to make Retinol Binding Protein (RBP) which liberates vitamin A from liver storage to tissues for utilisation. Without zinc, vitamin A is trapped. So optimise intake of zinc-rich foods.
What are the sources of Vitamin D?
Unlike other vitamins, Vitamin D is not essential because it can be synthesised in the skin in response to sunlight. Dietary sources are only required in the absence of adequate sunlight (UVB).
Plant source: Vitamin D2 found in mushrooms (fungi), but these require good sun exposure.
Animal source: Vitamin D3 found in cod liver oil, oily fish (herring, mackerel, sardines, wild-caught salmon) and organic egg yolks.
Sun Souce: Sunlight»_space;> activates provitamin D»_space;>converts to D3
Like most vitamins D2and D3 need activating in the body before they can become biologically useful. They both first need to be converted (hydroxylated) through processes in the liver and kidneys.
What serum leavels represent deficient, sufficient and optimal?
Deficient < 25 nmol/L
Sufficient @ 50 nmol/L
Optimal @ 75-125 nmol/L
How do you know if the sun you are exposed to is strong enough to make vitamin D?
If your shadow outside is the same height or shorter than you are, you’re getting enough sunlight to make vitamin D.
10 minutes of summer sun exposure results in endogenous (internal) 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.
Vitamin D, because it is fat soluble, can be stored in the liver for 4 months.
What dosage of Vitamin D is recommended?
D3 is 3 x more potent than D2 and stays in circulation longer.
RNI - 400 iu per day
Tolerable upper limit is 4000 iu per day. 10 x RNI
In summers we make it and store it for up to 4 months so in Summer if exposed to sunlight we are unlikely to need a supplement
If at the end of Summer you want to maintain sufficient levels recommend 2000 iu a day of D3 to keep levels topped up through winter.
If deficient a maintenance dose is not enough to bring it up to sufficient let alone optimal levels.
If severe deficiency – 50,000 IU orally once a week for 2-3 months or 3 times weekly for 1 month. Then test.
What are the key functions of Vitamin D
The biggest role is to maintain a tight calcium range in the blood. It does this by:
* Modulate the absorption of calcium in the gut
* Reduce the excretion of calcium
* Mobilise calcium from the bone when we need to in order to keep levels where they need to be
Functions:
Bone Health - supports bone density (with K2) ny increasing intestinal calcium absorption
Immune function and regulation - an immunomodulator which means it can dial up or dial down the innate and the acquired immune system as need by the body
GIT Health - helps to regulates mucosal inflammation, Vitamin D colonise a diverse healthy microbiome, stabilises tight junctions of epithelial cells of the small intestine,
Anti-Cancer - Enhances the anti-tumour activity of innate immune cells. Downregulates genes that are involved in cell proliferation to slow down spread and upregulate genes that inhibit angiogenesis
Insulin - Increases cellular sensitivity to insulin.
What are the signs and symptoms of deficiency in Vitamin D?
- Rickets (children) and osteomalacia (adults): Demineralised bones. Presents with bone pain and bowing of lower limb bones
- Osteoporosis (brittle bones) — fractures
- Immune system dysregulation: Severe asthma in children; frequent colds and infections; immune dysfunction (autoimmunity, allergies), insomnia, nervousness, depression, MS
- Menstrual irregularities (increases FSH / LH production).
- Non-specific musculo-skeletal pain and fatigue – fibromyalgia and chronic fatigue
What causes vitamin D deficiency?
- Inadequate UVB sun exposure and overuse of conventional sunscreens.
- Dietary factors such as excessive animal protein or calcium intake - More calcium in the diet, the more we downregulate Vit D formation and upregulate its excretion.
- Lack of dietary fats (it is a fat-soluble vitamin)
- Lack of magnesium (it is a co-factor for vitamin D synthesis.
- Impaired liver functionality (compromised vitamin D conversion) due to toxic burden - excess alcohol, drugs, caffeine use, pesticides, environmental and household chemicals.
- Elderly patients and those with a history of kidney disease.
- Poor intestinal absorption of dietary vitamin D (e.g., due to cystic fibrosis, coeliac disease, dysbiosis) and a lack of bile.
Can Vitamin D Supplememntation be toxic?
What does it look like?
Are there any drug interactions?
Can Vitamin D levels be toxic?
* We start to see toxicity at serum levels of 375 nmol/L but this takes some doing! Very high doses of 50,000 nmol/L for a month or more.
* TUI Level for Adults: 4000 IU / day.
* Vitamin D synthesis due to sunlight does not produce toxicity.
Toxicity can occur taking supplemental vitamin D at more than 50,000 IU per day for one to several months.
Individuals with vitamin D toxicity usually have blood levels above 375 nmol / L.
Main toxicity symptoms sue to vitamin D-related hypercalcaemia - excess calcium in the blood.
Calcium is excitatory, contracting muscles.
- Too much calcium circulating that gets into tissues like the heart it can lead to high blood pressure and an over excited heart and therefore contribute to an irregular heartbeat for example.
- Other symptoms: nausea, diarrhoea, vomiting, weakness, constipation.
Drug interactions:
Osteomalacia risk due to low vitamin D is increased with use of barbiturates and anticonvulsants.
What are the key functions of Vitamin E?
-
Antioxidant - Vitamin E’s primary role is as a scavenger for free radicals.
- Protects fat in the body and food from oxidation and free radicals and this reduces cellular ageing, inflammation, tissue irritation
- Protects Nerve sheaths from oxidation
- Protects Cholesterol from oxidation (↓ LDL oxidation) - Immunity- Increases phagocyte activity, differentiation of immature T cells in the thymus, Antioxidant and mild antiinflammatory properties
- Antocoagulant
- Endocrine -Improves insulin action (possibly improves insulin resistance), modulates oestrogen receptors and activity
- Skin repair
What is the dosage of Vitamin E?
Do we see toxicity?
RDA is 15 mg a day.
Tolerable upper limit is 1000 mg.
Toxicity is rare:
What are the sources of Vitamin E
Fresh, raw food sources are best:
* Sunflower seeds
* Almonds
* Pine nuts
* Olive oil
* Avocado
* Sweet potato
* Spinach
* Wheatgerm
Up to 80% of vitamin E is destroyed by freezing, whilst heating destroys around 30% of vitamin E.
What does Vitamin E deficiency look like?
A marginal subclinical deficiency is common.
Serious deficiencies are rare unless significantly impaired absorption (i.e., cystic fibrosis).
Typically presents as:
* Red blood cell destruction is one of the first signs (due to erythrocyte oxidation rate faster than bone marrow can replenish them). We have less capacity to carry oxygen to the tissues – Haemolytic anaemia — exhaustion after light exercise.
* Easy bruising and slow healing (fewer antioxidants).
* Nerve damage (e.g., neuropathy) due to oxidation.
Where does Vitamin K get its name?
Named after K for koagulation (German spelling). Its main function is blood clotting.
What mineral is required by B1 to create the active form of B1 called TTP?
Magnesium
What are the 3 types of Vitamin K and what are their sources?
Three types of compound have vitamin K activity: K1, K2, K3.
K1
* the dietary source found in green leafy vegetables (highest source) — natural form, making up about 80–90% of daily intake.
* Best absorbed with some dietary fat, e.g., steamed broccoli, spinach, kale with extra virgin olive oil.
K1 must be converted to K2 (the more active form) in the body to be utilised.
and dark green leafy vegetables (K1). Best absorbed with some dietary fat, e.g., steamed broccoli, spinach, kale with extra virgin olive oil.
K2
* Richest source is Natto -fermented soya beans. 7-8 x potency of Kale
* Synthesised by bacteria, found in fermented foods, making up around 10% of daily intake. Probiotics can support intestinal K2 production. K2 synthesis by bacteria occurs in the human jejunum and ileum, and is absorbed to a limited extent.
K3 (menadione): A potentially toxic synthetic form used in livestock.
Dosage and toxicity of Vitamin K
- Few countries set an RDA. Adequate intake estimated at 90-120 Mcg.
- Optimal intake is 300–500 mcg / day. K2 is better absorbed and tends to stay within the body for longer. Why? K1 precursor and K2 preformed
- Only small amounts are stored (mainly in the liver) and a regular dietary supply is required. Daily green Veg. Approx 30–40% of ingested vitamin K is retained, the rest is excreted.
- Reduced absorption: High vitamin A intake, aspirin. Low bile secretion and poor fat absorption disease states.
Toxicity: K1 and K2 are not known to be toxic (K3 can be).
What are the functions of Vitamin K?
- Blood Clotting - required for the fomation of 4 out of the 13 clotting factors
- Bone mineralisation - Osteocalcin is a calcium binding protein that requires Vitamin K for sysnthesis. It gets calcium into the bones
What causes deficiency of Vitamin K ?
- Liver diseases because this is where Vitamin K is metabolised
- Warfarin antagonises Vitamin K
- Antibiotic use affects microbe balance where K2 is produced
- Fat malabsorption issues.
Maternal considerations: At birth vitamin K levels in babies is usually very low and breast milk is not abundant in vitamin K. The baby will not have been able to consolidate their gut bacteria yet and therefore K2 production from bacteria is impossible. A vitamin K injection is offered at birth to newborns to prevent potential haemorrhagic disease
