Lecture 8 Flashcards
(168 cards)
1
Q
What are ‘vitamers’?
A
Different chemical forms of each vitamin. Vitamers are generally similar in structure.
2
Q
Key functions of vitamins
A
– Supporting the immune system.
– Regulating gene expression.
– Supporting neurological activity.
– Facilitating ATP production.
– Manufacturing of blood cells.
– Regulation of hormones.
Vitamins facilitate physiological functions in the body and are required for the activation of vitamin-dependent enzymes (function as ‘co-factors’).
3
Q
Where are vitamins absorbed?
A
Small intestine. It is, therefore, vital to optimise GIT health.
4
Q
Definition and structure of vitamins
A
Vitamins are carbon-containing compounds that are essential to the body in small amounts for normal growth and function.
Vitamins (as they occur in food) are relatively ‘inert’ until the body activates them.
5
Q
Name fat-soluble vitamins. How are they absorbed and stored in the body?
A
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.
6
Q
Water-soluble vitamins + their absorption and storage
A
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 in excess.
7
Q
The active forms (vitamers) of vit A
A
Retinol, retinal and retinoic acid
8
Q
Pro-vitamin A conversion, examples and toxicity
A
Pro-vitamin A → converted into the active (usable) form of vitamin A (retinol) in the small intestinal epithelium and liver.
– Carotenes (or carotenoids) are examples of pro-vitamin A. Found in non-animal foods.
Dietary carotenes are converted to vitamin A only as needed, so do not have toxicity concerns.
9
Q
Pre-formed vitamin A
A
Pre-formed vitamin A → this is active vitamin A the body can use as it is.
Only found in animal foods.
10
Q
Food sources: Pro-vitamin A
A
Produced by plants, algae, fungi and bacteria.
Rich food sources: dark green, yellow / orange vegetables and fruit, e.g., carrots, squash, mango, spinach, sweet potatoes.
11
Q
Food sources: Pre-formed vitamin A
A
Only found in animal foods e.g., liver, fish, liver oils, egg yolk, mackerel, salmon.
12
Q
How to increase the bioavailability of carotenoids?
A
- Add healthy fats as carotenoids are fat-soluble. Drizzle with coconut oil or olive oil to optimise absorption.
- Cook (slightly steam). This cooking method is
thought to most effectively liberate carotenoids from cells.
13
Q
Carotenoids and Conversion
A
The enzyme which converts carotenoids to retinal (in the intestinal epithelium and liver) is encoded by the BCO1 gene.
14
Q
Carotene conversion is reduced by what conditions
A
Hyperlipidaemia, liver disorders, diabetes and hypothyroidism.
15
Q
Pre-formed vitamin A absorption and toxicity
A
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).
16
Q
Vitamin A Supplemental range and contraindication
A
Adults maximum 3000 mcg preformed A. It is recommended to avoid isolated beta-carotene supplementation, as it was shown to worsen the progression of lung cancer patients (antioxidants do not work in isolation).
17
Q
Vitamin A functions: Vision and eye health
A
- 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.
- Also necessary for corneal health.
Photosensitivity
Visual loss
Night-blindness
Senile cataracts
18
Q
Vitamin A: Immunity
A
- Enhances T-cell proliferation and interleukin-2 secretion.
- Supports the first line of immune defence (skin and mucous membrane barrier).
Recurrent infections
19
Q
Vitamin A: Gene expression and cell differentiation
A
- Control of cell differentiation and turnover. Regulates the expression of over 500 genes, and affects 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.
Acne
Anaemia
Cervical dysplasia
Hair loss in women
Fracture repair
Lichen planus
Osteoarthritis
GIT ulceration
Vaginitis
Periodontal disease
20
Q
Vitamin A: Reproduction
A
- Reproductive & embryonic health.
- Required for spermatogenesis in men.
- Required for egg (ovum) development and implantation.
Infertility (male and female)
Fibrocystic breast disease
21
Q
Vitamin A: Antioxidant properties
A
- 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.
Used in various therapies, including carrot juicing for cancer (Gerson therapy).
Disease prevention
22
Q
Vitamin A: Deficiency signs and symptoms
A
- Vision impairment at night is an early sign.
Prolonged deficiency can lead to blindness. - Hyperkeratosis of the 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).
23
Q
What reduces levels of Vitamin A in the body?
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.
- Zinc deficiency and / or protein malnutrition: 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.
24
Q
Vitamin A toxicity can lead to
A
- Birth defects.
- Increase osteoclast activity and lead to bone fractures.
- Liver disease.
- Hyperlipidaemia, amenorrhoea and anorexia.
- Can cause dry, red and scaling skin.
25
Vitamin A drug interactions
Vit A decreases vitamin K absorption (increasing bleeding risk).
26
2 types of vitamin D
– Plant source: Vitamin D2 is ergocalciferol found in mushrooms (fungi), but these require good sun exposure.
– Animal source: Vitamin D3 is cholecalciferol found in cod liver oil, oily fish (herring, mackerel, sardines, wild-caught salmon) and organic egg yolks.
Vitamin D2 and D3 do not have any direct functions; they both first need to be converted (hydroxylated).
D2 and D3 have the same activation pathway via the liver and then kidney.
27
Vitamin D optimal range in a blood test
75–125 nmol / L
28
Vitamin D supplemental dose
A supplemental dose of 4000 IU / day has been used without adverse effects.
Ergocalciferol is less than one-third as potent as cholecalciferol, so D3 is favoured for supplementation. D3 supplements also stay in circulation longer.
29
The actions of vitamin D are mediated
through
a nuclear transcription factor known as the vitamin D receptor (VDR) within the nucleus of each cell. VDR activation is thought to directly and / or indirectly regulate 100 to 1,250 genes.
30
Vitamin D: Bone health
Supports bone density (along with vitamin K2), by increasing intestinal calcium absorption.
* Osteoporosis
* Osteomalacia and rickets
31
Vitamin D: Immune function & regulation
Supports immune function by:
– Enhancing innate immune system
– Regulation of T-helper cells
– Producing antibacterial peptides.
– Inhibiting eosinophils
– Reducing inflammatory cytokines (e.g., IL-6 and TNF-α) and prostaglandin production.
* Allergies
* Autoimmunity, e.g., multiple sclerosis
* Infections (e.g., viral and bacterial)
* Musculoskeletal pain reduction
32
Vitamin D: GIT health
- VDR helps to regulate mucosal inflammation.
- Vitamin D has a role in commensal bacterial colonisation.
- Intestinal VDR stabilises tight junctions.
Intestinal inflammation, e.g., inflammatory bowel diseases, intestinal permeability.
33
Vitamin D: Anti-cancer
- Enhances the anti-tumour activity of innate immune cells.
- Regulates multiple genes through the VDR, and inhibits angiogenesis.
Cancer prevention and support
34
Vitamin D: Insulin
– Activates transcription of the insulin gene (increasing insulin secretion).
– Increases cellular sensitivity to insulin.
Diabetes mellitus
35
Vitamin A and D Interaction
The balance of vitamins A and D is essential for proper gene transcription.
* The retinoid X receptor (RXR) is a type of nuclear receptor that is activated by vitamin A.
* Together the VDR / RXR form a complex with DNA for transcription.
* From a disease-prevention approach, maintaining healthy levels of vitamins A and D is crucial for correct gene expression.
36
Vitamin D: Deficiency signs and symptoms
* Rickets and osteomalacia: Demineralised bones. Presents with bone pain and bowing of lower limb bones.
* Osteoporosis (brittle bones) — fractures.
* Severe asthma in children.
* Poor immunity or immune dysfunction
(autoimmunity, allergies), insomnia, nervousness, depression.
* Menstrual irregularities (increases FSH / LH production).
* Non-specific musculoskeletal pain and fatigue
37
Causes of vitamin D deficiency
* Inadequate UVB sun exposure and overuse of conventional sunscreens.
* Excessive animal protein or calcium intake can affect its rate of formation and clearance.
* Lack of dietary fats, and a lack of magnesium (it is a co-factor for vitamin D synthesis).
* Breastfeeding without adequate sunlight / supplementation.
* Impaired liver functionality (compromised vitamin D conversion) due to excess alcohol, drug and caffeine use, as well as a large toxic burden from the diet (e.g., pesticides), environmental and household chemicals.
* Elderly patients and those with a history of kidney disease.
* Poor intestinal absorption of dietary vitamin D and a lack of bile.
38
Vitamin D toxicity symptoms
Main toxicity symptoms due to vitamin D-related hypercalcaemia: nausea, diarrhoea, vomiting, weakness, hypertension, constipation.
* Toxicity can occur at more than 50,000 IU per day for one to several months.
39
Two families of Vitamin E. What form is recognised for human nutrition?
Vitamin E is a generic term for two families of fat-soluble compounds with vitamin E activity: Tocopherols and tocotrienols.
The only form recognised for human nutrition is α-tocopherol.
40
Fresh, raw food sources of Vitamin E
Sunflower seeds, almonds, pine nuts, olive oil, avocado, sweet potato, spinach.
41
Vitamin E loses in cooking and storing
Up to 80% of vitamin E is destroyed by freezing, heating destroys around 30% of vitamin E.
42
Vitamin E storage and circulation
The liver takes up all forms of vitamin E and preferentially secretes α-tocopherol into circulation within lipoproteins.
Circulated everywhere, stored to the greatest extent in adipose tissue.
43
What increases the requirement for vitamin E?
Polyunsaturated fatty acid (PUFA) intake due to its antioxidant properties which protect the fatty acid double bonds from oxidation.
44
Naturally-sourced vs Synthetically produced form of Vitamin E
Naturally-sourced vitamin E = d-alpha-tocopherol.
Synthetically produced form = dl-alpha-tocopherol.
L isomers are less active. Synthetic forms of vitamin E are derived from petroleum oil and should be avoided.
45
Vitamin E function and therapeutics: Antioxidant
Protects the following from oxidation:
– Polyunsaturated fatty acids (PUFA) cell membranes
– Nerve sheaths
– Cholesterol (↓ LDL oxidation)
A vital ‘chain-breaking antioxidant’.
Vitamin C and selenium support the activity of vitamin E by rejuvenating oxidised vit E.
* Atherosclerosis and cardiovascular disease
* Male fertility
* Healthy ageing
* Cataracts
* Alzheimer’s and cognitive decline
* Anti-cancer
46
Vitamin E function and therapeutics: Immunity
- Increases phagocyte activity
- Differentiation of immature T cells in the thymus
- Antioxidant and mild anti-inflammatory properties.
* HIV / AIDS
* Healthy immune functioning
* Infections
47
Vitamin E function and therapeutics: Anticoagulant
Inhibits platelet aggregation and vitamin K activity (↓clotting factors)
* Cardiovascular disease
48
Vitamin E function and therapeutics: Endocrine
- Improves insulin action (possibly improves insulin resistance)
- Modulates oestrogen receptors and activity
Diabetes mellitus
Dysmenorrhoea
Menopause (e.g., vaginal dryness)
49
Vitamin E function and therapeutics: Skin Repair
Traditional topical use, although mechanism not understood.
* Scarring
* Acne
50
Vitamin E deficiency
* 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 (due to erythrocyte oxidation → haemolytic anaemia) → exhaustion after light exercise.
– Easy bruising and slow healing (fewer antioxidants).
– Nerve damage (e.g., neuropathy) due to oxidation.
51
Vitamin E Toxicity
Rare. High doses with vitamin K deficiency and / or warfarin, can increase bleeding risk. Caution supplements with chemotherapy.
High supplement doses create potential for pro-oxidant effect.
52
What 3 types of compound have vitamin K activity?
K1, K2, K3
53
K1 (phylloquinone)
The dietary source found in green leafy vegetables — natural form, making up about 80–90% of daily intake. K1 must be converted to K2 in the body to be utilised.
54
K2 (menaquinones)
Synthesised by bacteria, found in fermented foods, making up around 10%. Probiotics can support intestinal K2 production. K2 synthesis by bacteria occurs in the human jejunum and ileum, and is absorbed to a limited extent.
55
K3 (menadione)
A potentially toxic, synthetic form used in livestock.
56
Vitamin K: Richest food sources
Natto and dark green leafy vegetables. Best absorbed with some dietary fat, e.g., steamed broccoli and kale with extra virgin olive oil.
57
Vitamin K: Dosage and Absorption
Optimal intake is 300–500 mcg / day.
K2 is better absorbed and tends to stay within the body for longer. Only small amounts are stored (mainly in the liver) and a regular dietary supply is required.
* Reduced absorption:
- High vitamin A intake, aspirin.
- Low bile secretion and poor fat absorption disease states.
58
Vitamin K functions: Blood clotting
Vitamin K is required for the formation of 4 out of the 13 clotting factors (II, VII, IX, X).
Prevents bleeding (it is an antidote to warfarin). Vitamin K is recycled via the vitamin K cycle — warfarin inhibits this.
59
Vitamin K functions: Bone mineralisation
- Osteocalcin (a calcium binding protein in bones) requires vitamin K for synthesis.
- Osteocalcin synthesis by osteoblasts is regulated by active vitamin D (calcitriol).
Osteoporosis (45 mg / day, and by supporting microflora).
Prevents calcium accumulation in arteries
and kidneys.
60
Vitamin K: Causes of deficiency
Liver diseases, warfarin, antibiotic use, fat malabsorption issues.
Maternal considerations: Vitamin K transfer to the foetus via the placenta is not significant.
Maternal medications such as antibiotics, anticonvulsants and warfarin can dramatically reduce stores.
61
Vitamin K: Deficiency signs and symptoms
Excessive bleeding (haemorrhages), bruising, bone fractures, soft tissue calcification.
62
Vitamin K Injection for newborns: Considerations and alternatives
* Undesirable preservatives.
* Has not been tested for adverse effects.
* It is a synthetic chemical.
* The risk in full-term babies is low.
* A larger dose is given.
Alternatives:
* Delayed cord clamping until the placenta has fully pulsed out.
* Increase intake of vitamin K-rich foods before due date, and support mother’s microflora.
* Nettle leaf infusions.
63
B1 other name
Thiamine
64
B1: active form, dependent on and impaired by
Vitamin B1 functions in the body as the active form ‘thiamine pyrophosphate’ (TPP); conversion to this enzyme is dependent on magnesium, and impaired by alcohol.
65
B1 content is reduced by (processing methods)
Processing including milling, chopping, canning, adding sulphites (e.g., dried fruit), baking soda. Boiling or freezing reduces B1 content by 50%. Toasting bread reduces B1 by 30%. Fresh, raw sources are best.
66
B1 Food sources and storage
Bodily stores of B1 would last for approximately 1 month.
Yeast extract, peas, oranges, nuts (e.g., macadamia), pulses, sunflower seeds, whole grains, meat / fish.
67
B1 functions: Energy (ATP) production
- Crucial for carbohydrate, fat and protein metabolism.
- Needed for the formation of Acetyl-CoA (key for ATP production).
Fatigue
Supporting energy production in increased need (e.g., pregnancy, heart failure)
Fertility
68
B1 functions: Nervous system functioning
- Acetyl-CoA is an important precursor of acetylcholine
- The amino acids that are metabolised by thiamine can be used to create neurotransmitters e.g., GABA.
Cognitive decline and memory loss
Alzheimer’s
Low mood
Parkinson’s
Nerve repair
69
B1 Dietary requirements
The more carbohydrate you eat, the more B1 you need (i.e., to create ATP from it). An average of 0.4–0.5 mg / 1000 kcal is recommended.
70
B1 absorption is impaired by
Alcohol, tea (tannins), coffee, the OCP, stress and antacids
71
B1 Deficiency
- Beriberi is the primary deficiency disease. A white rice diet is thiamine depleted.
- Alcoholics are particularly prone to deficiency — ‘cerebral beriberi’ (Wernicke-Korsakoff syndrome) is most common Western cause.
72
B1 Symptoms of subclinical deficiency
* Depression, irritability, fatigue, memory loss, muscle weakness and cramps, GIT disturbance.
* Elderly people are frequently more depleted of thiamine and can benefit from it.
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B2 other name
Riboflavin
74
B2 contents are reduced by
Riboflavin is very sensitive to light, and content is also reduced by heating / boiling, freezing and leeching into cooking water (yellows the water).
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B2 food sources
Yeast extract, spinach, wild salmon, mushrooms, almonds, quinoa, lentils, kidney beans, organic eggs, meat.
76
B2 functions: Energy (ATP) production
- Metabolism of carbohydrates, fats
and proteins.
- For Krebs cycle and beta-oxidation
- B2 is a constituent of 2 key energy carriers: FAD (flavin adenine dinucleotide) and FMN (flavin mononucleotide)
Fatigue
Migraines (400 mg / day)
Stress (multiple B vitamins are depleted during times of stress)
77
B2 functions: Liver detoxification
* Detoxification via CYP450 enzymes (phase I liver detoxification system).
* Regeneration of glutathione
Liver detox programmes
78
B2 functions: Iron metabolism
B2 is required for iron metabolism
- Anaemia
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B2 absorption
Maximum absorption from a single dose is 27mg. Bile salts help intestinal absorption. Antacids and alcohol impair absorption.
80
B2 bioavailability
Bioavailability is impaired by:
* Copper, zinc, caffeine, theophylline (in chocolate), saccharin.
81
B2 dosage
Doses between 90–400 mg per day (split through the day).
* Smoking can reduce levels in the body. B2 demands are increased with heavy exercise, pregnancy and ageing.
82
B2 Deficiency
Depletion is common but deficiency is rare. More likely to occur in combination with other water-soluble vitamin deficiencies.
83
Vitamin B3 other name
Niacin
84
Vitamin B3 can be synthesised by the body from
The amino acid tryptophan.
Vitamin B3 is only essential when tryptophan metabolism is altered.
85
The two compounds with niacin activity are
Nicotinic acid and nicotinamide. The active forms of niacin are: NAD and NADP, which are energy-carrying molecules.
86
B3 food sources
Mushrooms, green leafy vegetables, yeast
extracts, sunflower seeds, salmon, sardines, peanuts, avocado, meat and poultry.
Cooking reduces B3 in foods.
Tryptophan-rich foods, e.g., bananas, turkey.
87
Cofactors for the synthesis of B3 from tryptophan
B2, B6 and iron
88
B3 supplementation can cause
Niacin flush: Skin flush and itch
89
B3 absorption and storage
* Absorption is in the small intestine.
* Stored mostly in the liver, heart, muscles and kidney.
90
B3 functions: Energy (ATP) production
The two coenzymes (NAD, NADP) participate in:
– Glycolysis
– Acetyl CoA formation
– Krebs Cycle
– Fatty acid oxidation
* Fatigue
* Supporting energy production in increased need
* Alzheimer’s
91
B3 functions: cardiovascular
- Lowers secretion of LDL
- Vasodilatory effects (lowers BP)
* Hyperlipidaemia
* Cardiovascular disease
92
B3 functions: insulin
Part of Glucose-tolerance factor (GTF) - an important role in the insulin response.
* Insulin resistance
(i.e., Type 2 diabetes, PCOS)
93
B3 deficiency signs and symptoms
* Severe deficiency (‘pellagra’): Four Ds — diarrhoea, dermatitis (characteristic collar rash), dementia, death (within 4–5 years).
Pellagra can occur in diets deficient in both protein and niacin.
* Mild deficiency / insufficiency symptoms:
Unrelenting fatigue, vomiting, depression, indigestion, canker sores, sensitivity to strong light, red tongue and inflamed gums.
94
B3 toxicity / adverse events
Hypotension, hyperuricaemia, flush, hypothyroidism, hepatotoxicity.
95
What condition can be worsen by B3 supplementation?
Niacin competes with urate for excretion so
supplementation can worsen gout.
96
Vitamin B5 other name
Pantothenic Acid.
Pantothenic = from Greek for ‘found everywhere’ (i.e., found in many foods)
97
B5 Food sources
Richest food sources include shiitake mushrooms, avocados, nuts, seeds, fish and meat. However, it is found widely distributed in almost all foods.
98
B5 synthesis + can be reduced by
Synthesised by intestinal bacteria.
Antibiotics may reduce synthesis.
Sensitive to processing, cooking and freezing with up to 80% loss.
99
B5 functions: ATP production
- Metabolism of carbohydrates
and proteins.
- Required for Acetyl CoA formation.
* Fatigue
* Supporting energy production in increased need
100
B5 functions: Fat metabolism
The synthesis and degradation of fatty acids.
* Acne vulgaris (sebum)
101
B5 functions: Stress hormones
- Acetyl-CoA → neurotransmitters (i.e., increased GABA)
- A co-factor for stress hormones (used up quickly when stressed)
* Adrenal fatigue
102
B5 functions: Antihistamine
- Antihistamine properties.
* Allergies
* Hay fever
103
B5 deficiency and symptoms of deficiency
Deficiency is rare. However, depletion
may occur with high alcohol use, prolonged stress and recent surgery.
Deficiency symptoms: Burning sensation in feet and tender heels, fatigue and abdominal distress.
104
Vitamin B6 other name
Pyridoxine
105
The active forms of B6
pyridoxal 5’-phosphate (PLP) and pyridoxamine 5’-phosphate (P5P)
106
B6 Food sources
Widely distributed: Whole grains, green vegetables, sunflower seeds, pistachios, walnuts, bananas, lentils, avocados, meat, fish.
107
B6 bioavailability and depleted by
Approximately 75% bioavailable.
Intestinal flora synthesises large amounts.
Processing, preserving, heating and light exposure reduce B6.
Alcohol excess, the OCP and GIT issues increase requirements.
108
B6 functions: Neurotransmitter production
Synthesis of:
– GABA
– Dopamine
– Noradrenaline
– Serotonin
* GIT motility (digestion)
* Carpal Tunnel Syndrome
* Morning sickness
* Lactation and PMS
109
B6 functions: Red blood cell formation
Used for haem production.
* Anaemia
110
B6 functions: Methylation
Lowers homocysteine.
* Cardiovascular
disease
111
B6 function: Energy production
Amino acid metabolism, releases stored glucose.
* Fatigue
112
Increased need for vitamin B6 occurs in
Alcohol dependence, long periods of high stress, pregnancy — particularly in third trimester, hormonal imbalances, hyperhomocysteinemia (with folate / folic acid and vitamin B12).
113
B6 Deficiency symptoms
Deficiency is rare, and occurs alongside other deficiencies.
Symptoms: Low B6 affects the metabolism of fatty acids leading to skin lesions and dermatitis. Tongue inflammation, recurrent
mouth ulcers and sores on the corners of the mouth, hormonal imbalance (e.g., PMS), anaemia (fatigue, pallor, etc.), depression.
114
Drug interactions
Many drugs deplete B6 levels and so intake should be increased.
This includes anticonvulsants, antibiotics, alcohol, chemotherapy drug ‘docetaxel’ and the OCP.
Levodopa (Parkinson’s medication) on its own is broken down by B6 so it should not be supplemented
115
Vitamin B7 other names
B8 / H — Biotin
116
How was biotin discovered
due to its deficiency state brought about by raw egg consumption
117
B7 Food sources include
Egg yolk, yeast, whole grains, cauliflower, sweet potato, nuts, meat, oily fish.
118
B7 functions: Gene regulation
- Regulates gene expressions.
- Particularly supportive of rapidly regenerating tissues, e.g., skin, hair and nails.
* Dandruff
* Brittle nails
* Dry / brittle hair
* Cradle cap
119
B7 functions: Blood-sugar regulation
In combination with chromium, biotin has been shown to improve blood-glucose control
* Diabetes mellitus
* PCOS
120
B7 deficiency symptoms
Dermatitis, dry scaly flaky skin (i.e. mouth and nose), smooth pale tongue, hair thinning and loss, depigmentation.
* Deficiency can occur in rare metabolic disorders (tested at birth), due to biotin deficient formula or tubal feeding.
121
B7 synthesis, absorption and depletion
Intestinal production can be reduced due to
prolonged use of antibiotics.
Anticonvulsant drugs, steroid hormones and alcohol may inhibit absorption.
A vegetarian diet may enhance biotin synthesis and absorption.
Biotin supplementation interferes with laboratory tests.
122
Vitamin B9 other name
Folate. Foliage = folium ‘leaf ‘(Latin)
123
The active form of folate in the body
THF (tetrahydrofolate), and its methylated derivatives
124
Folic acid, folinic acid and levomefolic acid
synthetic supplements or fortification forms, are not found in nature and can be dangerous, so should be avoided.
125
Folate food sources
Leafy greens, asparagus, avocado, Brussels sprouts legumes, citrus fruit (especially oranges) and liver.
126
Folate Absorption and bioavailability
Absorption requires adequate pancreatic enzymes. Losses occur from processing / cooking foods.
Main storage site is the liver (50%). Some folate is recycled in the liver and reabsorbed.
The microbiota produce some B9.
127
Folate trap
After absorption, a methyl group (–CH3) is added to folate and in this form, it is delivered to body cells.
Without the vitamin B12 enzyme which removes the methyl group, folate becomes trapped inside cells in its methyl form (5-methyl THF), unavailable to perform its main functions (DNA synthesis and cell growth) — a metabolic situation called the ‘folate trap’.
128
B9 forms and adverse effects
Folic acid is considered more available than
dietary folate, but it is less regulated and absorption is uncontrolled in the body. An adverse effect of high folic acid supplementation is nausea.
* It is advisable to recommend the methylated form of folate if supplementation is necessary.
129
B9 functions: Cardiovascular health
Methylation of homocysteine to methionine.
* Atherosclerosis
* Alzheimer’s
130
B9 functions: Formation of red blood cells
Required for erythrocyte synthesis. Without this, they are large and immature.
* Anaemia (B9 deficiency induced)
131
B9 functions: embryo health
Required for the healthy development of the neural tube.
* Prevents spina bifida (Dosage for conception 600 mcg / day)
132
B9 Deficiency signs and symptoms
Affecting rapidly dividing cell types; skin, GIT and blood cells: Skin and digestive issues, megaloblastic anaemia (severe deficiency)
133
B9 Factors related to deficiency
Alcoholism, OCP, diuretic and aspirin use. GIT
disorders, diets low in green leafy vegetables and old age.
134
Vitamin B12 other name
Cobalamin, cobalamin = from
cobalt + vitamin
135
The most active B12 analogues include
Methylcobalamin, hydroxycobalamin,
adenosyl cobalamin and cyanocobalamin.
These are the only analogues recognised
by the body. There are others found in
nature but they are not bioavailable to humans.
136
B12 synthesis, absorption and storage
Vitamin B12 is synthesised by bacteria. Vitamin B12 found in animal-based foods.
The human microbiota produces B12, but it is not absorbed.
B12 storage in the liver lasts between 3–5 years
137
Vegan B12 food sources
* Chlorella pyrenoidosa
* Korean purple laver
* Nutritional yeast, nori and kombu sea vegetables, shiitake and Lion’s mane mushrooms.
138
Animal B12 food sources
Meat, liver, milk, cottage and feta cheese, organic eggs, fish (esp. sardines, mackerel and wild salmon).
139
B12 functions: Nervous system
- Myelin production.
- Neurotransmitter production (dopamine, serotonin).
- Choline — key for brain function.
* MS
* Tingling / pins and needles
* Sciatica
140
B12 functions: erythropoiesis therapeutics
Megaloblastic anaemia
141
B12 functions: methylations
Homocysteine cycle (conversion of the amino acid homocysteine to methionine).
* Cardiovascular disease
* Alzheimer’s
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B12 functions: energy production
Energy production from fats and proteins.
* Fatigue
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Causes of B12 deficiency
* Poor nutrition (malnutrition):
– Lack of dietary B12 intake, and a diet rich
in highly-processed, nutrient-depleted foods.
* GIT causes (malabsorption):
– Stomach problems (e.g., lack of intrinsic factor, low hydrochloric acid production)
– Low pancreatic enzymes, small intestine issues (e.g., Crohn’s disease, coeliac), high alcohol.
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If a client has a good dietary intake of B12, yet is deficient, it highlights
a possible absorption issue or problem with methylation.
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B12 Deficiency states
The most common cause of deficiency is
malabsorption due to inadequate intrinsic factor (IF) production. It is called pernicious anaemia (an autoimmune attack on parietal
cells in the stomach).
Helicobacter pylori infection is also implicated.
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Increased vitamin B12 requirements
pregnancy, thyrotoxicosis, malignancy, liver and kidney disease.
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B12 Deficiency signs and symptoms
Changes occur slowly.
* Megaloblastic anaemia: Presenting as fatigue, breathlessness, pallor, etc.
* Neurological abnormalities: Tingling, numbness, loss of balance, burning sensations, weakness, confusion and decreased reflexes.
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B12 Testing
Serum B12 testing is the most common
means of assessing B12 conventionally.
* However, many people experience signs
of B12 deficiency with normal B12 serum.
* A more accurate reflection of B12 levels would involve testing methylmalonic acid (available in serum or urine testing) — gives an indication of how B12 is used in cell metabolism and is the gold standard test.
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B12 toxicity and drug interactions
B12 is one of the safest vitamins.
* The OCP, metformin, excessive alcohol, proton pump inhibitors and H2-receptor antagonists lower B12 levels.
* Calcium may enhance B12 absorption,
including with metformin use.
* People with autoimmune disease are
considered more at risk of pernicious anaemia.
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Vitamin C other name
Ascorbic Acid
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Vitamin C Food sources
All fresh raw fruit and vegetables, particularly
peppers, kiwi fruit, papaya, currants, berries,
citrus, crucifers, mangoes and tomatoes.
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Vitamin C loses
Very significant losses occur as vegetables
wilt, or when they are cut as a result of the
release of ascorbate oxidase from the plant tissue.
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How vitamin C prevents the browning of fruit
Ascorbate oxidase is why lemon or lime juice can prevent the browning (oxidising) of other foods (e.g., sliced apple) — the vitamin C creates an antioxidant barrier from oxygen until it is all used up.
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Vitamin C absorption and storage
* Absorbed in the mouth and in the small intestine (by active and passive means). Up to 100% absorption per 200 mg serving.
* Vitamin C concentrates in the adrenal glands, white blood cells, thymus and pituitary — although there is no specific storage site.
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Why diabetics and clients with sugar-laden diets may have low vitamin C levels?
Vitamin C is transported into cells by glucose transporters; so high blood glucose levels can inhibit vitamin C uptake significantly.
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High doses of what vitamin can skew blood glucose test results?
Vitamin C
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Factors that increase breakdown or excretion of vitamin C
Stress — psychological, chemical, emotional or physiological, fever and viral illnesses. Alcohol, smoking, heavy metals, aspirin, OCP.
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Vitamin C functions: Antioxidant and immune-boosting
- Primary water-soluble antioxidant in
blood and tissues — protecting proteins, lipids, carbohydrates, RNA and DNA from damage from free radicals.
- Recycles other antioxidants such as
vitamin E and glutathione — making
them usable again as antioxidants.
- Up-regulates interferons, natural killer
cells and T-cells.
* Cancer
* Cardiovascular
disease
* Alzheimer’s
* Asthma / COPD
* Cataracts
* Immune support (e.g., cold sores)
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Vitamin C functions: Cholesterol-lowering
Conversion of cholesterol to bile acids (lowering blood LDL levels).
* Cardiovascular disease
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Vitamin C functions: iron absorption
- Enhances iron absorption by protecting iron from oxidation. It keeps it in Fe2+ form, not allowing it to become Fe3+, which is not a bioavailable form.
* A dose of 25 mg of vitamin C taken
together with a meal increases iron
absorption by 65%.
* Anaemia
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Vitamin C endocrine functions
Synthesis of thyroxine and adrenal steroid hormones.
* Adrenal fatigue
* Hypothyroidism
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Vitamin C functions: collagen synthesis
- Co-factor for collagen synthesis.
- Important for forming strong tendons, ligaments and bones, repairing wounds, improving gum health.
* Osteoarthritis
* Cartilage injuries
* Ligament injuries
* Gum diseases
* Bruising
* Fracture repair
* Blood vessels
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Vitamin C functions: neurotransmitter synthesis
A co-factor in serotonin production.
* Weak digestion
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Vitamin C functions: energy production
Transport of long-chain fatty acids into the mitochondria for ATP production
* Fatigue
* Chronic fatigue
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Vitamin C Deficiency signs and symptoms
* Compromised blood vessel integrity:
– The gums bleed easily around the teeth.
– Capillaries under the skin break spontaneously producing pinpoint haemorrhages.
* approx. 1 month on a vitamin C depleted diet - Scurvy symptoms appear:
– Further haemorrhaging from inadequate collagen synthesis.
– Muscle degeneration and rough, brown scaly skin.
– Wounds do not heal. Bone rebuilding falters; fractures develop.
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Vitamin C Deficiency states
* During stress, the adrenals release vitamin C with other hormones into the blood, stress raises vitamin C needs — likely due to
additional free radical damage.
* Burns, infections, toxic metal intakes, chronic use of medications and cigarette smoking are among the stresses that increase vitamin C demand.
* Smokers have lower levels of serum vitamin C — 25 mg of vitamin C is lost with every cigarette smoked.
* Subclinical deficiency is common: Susceptibility to infections, poor wound healing, fatigue, skin and gum degeneration, petechiae.
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Vitamin C Dosage and tolerance
* 500 mg / day+ of vitamin C is a sound general dose.
* A high dietary intake of vitamin C is cancer-protective.
* 250 mg‒1 g of vitamin C can reduce the
incidence of colds by 50% in those who undertake strenuous exercise.
* Unabsorbed ascorbate from very high doses (3 g / day plus) is a substrate for intestinal bacterial metabolism causing gastrointestinal discomfort and diarrhoea (bowel tolerance).
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Vitamin C toxicity
* Vitamin C is non-toxic, even at extremely high doses.
* People with kidney disease and those with a tendency toward gout are prone to forming kidney stones if they take large doses of ascorbic acid over few months.
* Be mindful of high doses vitamin C with haemochromatosis.
* No high doses in the third trimester of pregnancy.
