Vitamin C is a very important nutrient for a number of reasons. It is essential for several functions in the body which I’ve listed below. It is extremely safe. In fact, in the absence of kidney damage there are no known toxicities, especially if taken IV.
Good sources: Rapid growing veggies (cabbage, broccoli, asparagus, brussel sprouts), citrus fruits, and raw potatoes, organ meats (liver)
RDA: 60 mg/d. There is an active pool in the body of about 1500 mg. There is a limit to Vit C absorption. If you consume 100 mg then 100% is absorbed. However, if you consume 12,000 mg then only 16% is absorbed. However, IV Vitamin C can achieve very high serum levels without toxicity signs or symptoms.
Functions: Vitamin C is required for several metabolic functions in the body. One of its major roles is in the synthesis of collagen and elastin, the main structural proteins of skin, cartilage and blood vessels. It is also necessary in the production of several stress response hormones including adrenalin, noradrenalin, cortisol and histamine, and it is required in the synthesis of carnitine, an amino acid that facilitates the conversion of fatty acids into energy within the mitochondria. Vitamin C protects against heart disease in several ways: it helps dissolve arterial plaque, reduces free radical oxidation of cholesterol, decreases levels of the atherogenic lipoprotein Lp(a), and maintains the elasticity of vascular walls which helps control hypertension. In addition, vitamin C boosts immunity by increasing production of white blood cells, increasing levels of antibodies and interferon and modulating prostaglandin synthesis. It enhances iron absorption, promotes efficient wound healing, and detoxifies the body by binding to certain heavy metals so they can be eliminated from the body. The anti-cancer effects of vitamin C stem from its role as a potent, water-soluble antioxidant in the plasma and cytoplasm. It also protects nucleic acids (DNA) from oxidative damage and inhibits the formation of nitrosamines (carcinogenic compounds formed in the digestive tract). Additionally, it can regenerate vitamin E and works synergistically with other antioxidants such as beta-carotene and glutathione to increase their overall antioxidant effect.
Antioxidant (see oxidative damage) – The plasma ascorbate concentration in an oxidatively stressed patient (less than 45 µmol/L) measured is lower than healthy individual (61.4-80 µmol/L) according to McGregor and Biesalski (2006). Increasing plasma ascorbate level may have therapeutic effects in oxidative stress. Individuals with oxidative stress and healthy individuals have different pharmacokinetics of ascorbate
Vitamin C donates electrons in enzymatic reactions and quenches free radicals in plasma & cytoplasm
Replenishes the antioxidant Glutathione
This protects DNA from damage
Reduces free-radical oxidation of cholesterol
Involved in numerous catalyst reactions
Collagen & elastin synthesis
- Vitamin C is a co-enzyme in hydroxylation reactions. If you will recall, proline and lysine are hydroxylated to form collagen.
- Promotes wound healing
Increases absorption of non-heme iron
Enhances immune function
- Increases production of white blood cells and interferon
- Modulates prostaglandin synthesis
Decreases levels of creatine kinase after exercise
Improves blood vessel dilation
Catalyzes conversion of dopamine to norepinephrine
Necessary for the synthesis of epinephrine, norepinephrine, cortisol, & histamine
Large doses (>2 grams) have an antihistamine effect
- Inhibits histamine-induced constriction of bronchial airways
Required in the synthesis of epinephrine
Regulates GABA (Gamma Amino Butyric Acid) receptors in the central nervous system (CNS)
Cofactor for carnitine synthesis
Cardiovascular protection
- Metabolizes cholesterol to bile acid conversion
- Dissolves arterial plaque
- May decrease the atherogenic potential of Lp(a)
Lowers glycosylated hemoglobin (HbA1c), fasting and post-prandial glucose levels in diabetic patients
Required for the synthesis and metabolism of tyrosine
Aids in the detoxification of heavy metals
Inhibits the formation of nitrosamines (carcinogenic compounds) in the stomach
Partially restores thyroid function when liver detoxification ability is compromised
Deficiency alters methylation patterns in cancer cells
- Cofactor to methylation enzymes
Hormone support
- Increases serum progesterone levels
- May induce ovulation in some women
- Enhances the effect of clomiphene, a fertility drug
- Estrogen-containing contraceptives lower vitamin C levels
- Increases estradiol (E2) in women on hormone replacement therapy
- Lowers aromatase in the ovaries
Lowers serum uric acid levels
Catalyzes reactions that regulate oxytocin, vasopressin, and cholecystokinin
Anti-cancer effects
- Slows age-related telomere shortening in human skin cells
- Protects prostate against testosterone-induced tumors
- Anti-cancer effects include formation of collagen to “wall off” tumors
Inhibits hyaluronidase, an enzyme that breaks down the matrix of cell walls
High Vitamin C intake can inhibit copper absorption
enhances chromium uptake
Regenerates Vitamin E. Supplementation with large amounts of either Vitamin C or Vitamin E increases the requirements of the other
Deficiencies: Deficiency symptoms include capillary fragility (due to its role in collagen formation) which often manifests clinically as bleeding/spongy gums, loose teeth, anemia, easy bruising, tender joints, muscle weakness and poor wound healing. Subclinical deficiency can also result in lowered immunity, anemia (due to vitamin C’s ability to enhance iron absorption) and fatigue (due to its role in the synthesis of carnitine and certain hormones).
Toxicity:
Vitamin C is one of the safest substance known.
- Diarrhea – it you take high enough doses orally
- Kidney stones (only if there is pre-existing kidney disease) – vitamin C is metabolized to oxylate which binds with calcium. They pack together to form a stone. If you increase magnesium, it binds with oxylate (instead of calcium) which is water soluble and can be eliminated.
- Dependency – If you consume large quantities orally, you can become dependent on that level of vitamin C. For example, if you consume 1 gram per day and then decrease consumption to 100 mg per day, you can have some withdrawal symptoms despite the fact that your intake is above the RDA.
- Rebound scurvy – along the same lines as described above but the symptoms are those of scurvy.
