Vitamin C Review and the Supplement War

Vitamin c is a water soluble vitamin that is very sensitive to heat.

Its found in citrus fruits, green vegetables, and tomatoes. Snap frying green vegetables seals in the nutrients, and they tend to have such a high proportion of c vitamins that light heating (blanching, steaming) will not destroy too much.

Deficiencies in the less serious stages tend to show up as problems relating to connective tissue growth and repair - like tender, swollen or bleeding gums, loosening of teeth, poor wound healing and bleeding. This relates to one of vitamin c's functions in the body - laying down collagen in connective tissue formation. Connective tissue can be found in blood vessels, tendons, ligaments and bone.

Deficiencies in the more serious stages lead to anemia and scurvy.

Vitamin c's functions are not all exactly known, but it is involved in many metabolic functions, especially protein metabolism. For example, vitamin c is involved in the synthesis of carnitine (an amino acid, which is a protein), which is part of the process that transports fat into cells to be used for energy production. It is also involved with the metabolism of cholesterol into bile salts; the immune system, and also functions as an antioxidant. It can even combine with poisons, making them harmless until the body excretes them.

The RDA for vitamin c is set at a level which prevents deficiencies but perhaps not chronic disease. The RDA for adult non smokers is 90 mg/day for men, and 70 mg/day for women. The RDA for smokers is 35 mg/day higher, due to the stress smoking places on the body. So that's 125 mg/day for men, 105 mg/day for women.

The tolerable upper intake, which is the maximum you can safely consume, is set much higher. It is 2000 mg per day for adults.

The Linus Pauling institute states that there is no difference biochemically between the natural and synthetic forms of vitamin c. One is not more available to the body than the other. Your choice as to what form of vitamin c you take is therefore based on the preference of what is most practical and convenient to your lifestyle.

Some interesting facts emerge about the types of c vitamins available on the market. This information is taken from the Linus Pauling site, which has further information on vitamin c bioavailability here.

The main forms of c in supplements are - mineral ascorbates, vitamin c with bioflavanoids, ascorbate and vitamin c metabolites, and ascorbyl palminate.

Mineral ascorbates

These are compounds of ascorbic acid with a mineral. There are many minerals that can be used in this process, but calcium and sodium are the most common. Basically you get a (comparatively) small amount of each mineral with the vitamin c. For example, 114 mg calcium per 1000 mg vitamin c (as ascorbic acid). The label on the supplement bottle will ususally indicate how much of each you get. This type of preparation is considered by some people less irritating to the stomach than ascorbic acid on its own. I personally never take vitamins on an empty stomach so don't find it a problem anyway. If attracted to this form of ascorbic acid for its mineral content, its important to note that the mineral content is minor. For example, the RDA for calcium is in the range of 1000 - 1500 mg. So 114mg is not going to supply you with 100% of the RDA for calcium. But if you have a particularly sensitive stomach, you may prefer this preparation.

Vitamin c with bioflavanoids

The intent of this type of preparaton seems to be to mimic nature's delivery of c vitamins. Bioflavanoids are part of many fruits and vegetables that are good sources of vitamin c, and they are believed to be antioxidants. However, as far as the antioxidant property of bioflavanoids, scientists are not always able to identify the exact or most powerful bioflavanoid antioxidants. Fruits and vegetables have many, and they often work synergistically. That is not always easy to replicate in supplemental form, at least at this stage. As far as the effect of supplemental bioflavanoids on vitamin c bioavailability or effectiveness, the Linus Pauling Institite states that there is not much evidence they increase either. Remember that vitamin c is in itself a powerful antioxidant. Rather than spend extra money on unproven (in supplemental form) antioxidants, it may be better to spend that money on a better quality multi vitamin, or some essential fatty acids.

Ascorbate with vitamin c metabolites

Ascorbic acid metabolites are chemical variations of vitamin c. The Linus Pauling Institute cites the only published study on the bioavailability of preparations with c vitamin metabolites with respect to preparations without metabolites, which found no difference in effectiveness in the body between them. This published study was done with the product Ester-C but I would certainly be taking this into consideration in evaluating all c vitamin metabolite products until further evidence showed me otherwise.

This is not to criticise those products - you will still get the ascorbic acid from them as per the dose you take. It is just useful to compare them to regular ascorbic acid, because they are all just as effective despite possible advertising claims to the contrary.

Ascorbyl palminate

This form of ascorbic acid is what you usually find in skin creams and lotions as its chemical form has been changed to an ester. That is, it is now a fatty acid - fat soluble not water soluble. Whilst this form of ascorbic acid is available as an oral supplement, it is not more useful that way as it would still be broken down in the body before it is used (ie the ascorbic acid would be separated from its companion, palmitic acid (the fatty part)). Ascorbyl palminate is marketed as vitamin c ester. Ester-C is not ascorbyl palminate. It belongs in the metabolite category.

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