VITAMIN C

VITAMIN C

1. FORM: Ascorbic acid human/primates, G pigs, Fish Source: Black/Red currants, Citrus fruits, Parsley, Pineapple, Rosehips, Straw, Rasp, Blackberries Peppers, Kiwi, watercress, bokchoy

2. RNI 10mg/d to prevent scurvy. 20mg/d optimum healing 40mg/d UK 0mth - 10 yrs - 25mg; 10-14 yrs 30mg; M&F 11-15 yrs 35mg M&F 15-50+ 40mg Dosage Suppl: 250-10,000mg. No high dosage in 3rd semester of pregnancy

3. FOOD SOURCE - Kale 120, Kiwi 108, Papaya 61, Strawberries 58, Oranges - 45

4. AVAILABILITY & ABSORPTION: Loss through leaching in water, through atmospheric oxidation when food left to stand, Refrigeration and quick freezing retains. Ascorbic and dehydroascorbic acids absorbed in mouth and SI. 80-95% is absorbed at 100 mg/d, absorption is lower in larger amounts. Unabsorbed ascorbate from v high does accounts for GI discomfort and diarrhoea. Process - Both vitamers transported by glucose transmitters and high blood glucose levels inhibits it significantly.

5. METABOLIC FUNCTIONS: VIT C loses electrons easily v effective antioxidant against free radicals & against tissue damage. In SI Vit C enhances iron absorption (keeping it in Fe2+ and not allowing it to become Fe3+ which is not bioavailable). Vit C 25mg taken with meal increases iron absorption by 65%.

   • PRO-OXIDANT - high levels of supplementation can create stress in body. When it reduces oxidising substances such as hydrogen peroxide, it reduces metal ions which leads to generation of free radicals through Fenton reaction. The metal ions in this reaction are reduced, oxidised and then re-reduced in a process that generates reactive oxygen species - free radicals.
   • Cofactor in collagen formation, Hydroxylation of carnitine, Conversion of typtophan and tyrosine to neurotransmitters serotonin and norephinephrine; Synthesis of thyroxin, adrenal hormones;
   • Inhibits Nitrosamine formation - resp for colon cancer. During stress adrenal gland contains more Vit C than any other organ and releases it with other hormones into the blood. Burns infections etc increase Vit C intake
   • CURE: cold although research has conflicting opinion

6. THERAPEUTICS - Age related macular degeneration (AMD) 500mg/d, with zinc 80mg, Vit E 400 IU, beta-carotene 15 mg/d - prevents visual loss Albuminuria - 1250mg + Vit E 680 IU can reduce protein excretion by 19%. Atheroscelorosis / peripheral arterial disease - 250mg/d; Mouth cancer, Gall bladder disease - increase Vit C levels reduces risk. Helicobacter pylori - oral 1g reduces gastritis, reduces precancerous changes; Osteoarthritis - Vit through diet reduces cartiliage loss, Vit C + Vit E reduces sunburn

7. DEFICIENCY: Gum bleed around teeth, scurvy - further haemorrhaging, muscle degeneration, rough, brown scaly skin, teeth become loose. Drug interactions - regular users of aspirin, barbiturates, OCP and low intake of fruits and veggies; smokers

8. TOXICITY - 3000 mg/d - nausea, abdominal, diarrhoea. Below 10g/day no toxicity. People with kidney disease prone to kidney stones with arge doses of C. DRUG INTERACTIONS - Cancer drugs - mixed views on anti oxidant factor; Oestrogens can increase when C taken with OCP. Counter acts with Statins/Niacins, Counteracts with Warfarin.