What the science says (1990–2026): Vitamin C
These citations support correction of deficiency, specified forms, and elemental amounts — the same logic used in MD's Choice formulas. They are not claims that a supplement treats disease.
Levine 1996 PNAS; Carr & Maggini 2017; 2023–2025 immune reviews. Ascorbate is required for collagen and is a water-soluble antioxidant. Routine mega-doses do not prevent colds in the general public; they can shorten colds slightly in some athletes and deficient people.
These products are not intended to diagnose, treat, cure, or prevent disease. Historic monograph text below is kept for the original library.
The steroid vitamin crosses the cell membrane and binds to cytosol receptor proteins
Activation of this complex within cytosol allows its entry into the nucleus and binding to chromatin
This results in increased formation and transfer into cytosol of mRNA for Ca and P transport proteins
This enhances rate of synthesis of proteins involved in Ca and P absorption or resorption
Receptors for 1,25(OH)2D are found in cells of other tissue (including pancreas and skin) so vitamin D may have other, as yet undiscovered functions
Because kidney activation of the vitamin-hormone is central to its action and regulation of blood Ca, loss of kidney function will produce hypocalcemia and bone disease
VI. Dietary Sources of Vitamin D
- Fish oils and egg yolks
- Milk and other supplemented processed foods
- Raw foodstuffs contain little or no vitamin D
VII. Deficiency
- Deficiency results from:
- Insufficient vitamin production
- Dietary lack
- Malabsorption of fats
- Levels of PTH are increased, which enhance urinary excretion of phosphorus and further reduce bone calcification
- Deficiency symptoms
- Rickets
- Appears during growing period (children)
- Poor calcification of bones
- Poor cartilage cell growth
- Deformities of bones
- Blood changes
- Serum 25(OH)D3 below 5 ng/ml (normal levels are 30 mg/ml in US and 20 ng/ml in Europe)
- Decreased serum Ca and P
- Increased serum alkaline phosphatic
- Osteomalacia
- Occurs in adults
- Bone reabsorption weakens bone
- May occur with failure to absorb fat and fat soluble vitamins
- Chronic renal failure causes a problem
VIII. Toxicity
- 10 times the RDA
- Symptoms
- Hypercalcemia (Ca> 12mg/dl) (also caused by hyperparathyroidism)
- Deposition of Ca in soft tissues (kidney, heart, lung, vasculature)
- Hypercalcuria, possibly stones
- Cardiac myopathy and afilerosclerotic lesions
- Melanin in the skin may protect man from vitamin D toxicity
- Exposure to equatorial versus Boston sunlight doubles the initial rate of pre-D3 production
- With increased exposure, previtamin D3 production decreased and increasing proportions of biologically inactive forms (lumisterol) were produced
