Is the common belief that if a little is good, then more must be better.  Although, many substances that provide beneficial effects to the body can be harmful, or even deadly, in large amounts.  Even water or oxygen can be harmful or deadly in high amounts, or in the right circumstances.

            Megadosing of vitamin C was made famous by the Linus Pauling Institute, especially among cancer patients.  The belief is that large amounts of vitamin C can boost the immune system, destroy pathogens, and protect the body from free radical damage safely because the excess vitamin C will be eliminated from the body.   Although, the use of massive doses of vitamin C for therapy by the Linus Pauling Institute is done for very short periods of time, up to a week. Even though short term megadosing of vitamin C may cause problems in some people, the risk of adverse effects greatly increases with long term use of excessive amounts of the vitamin. 

            Vitamin C does boost the immune system, and in does protect the body from some free radical damage.  And it is true that excess vitamin C can be eliminated from the body.  The practice of vitamin C megadosing does present some safety issues. 

            A severe deficiency of vitamin C can lead to a disease known as scurvy.  Symptoms of scurvy include connective tissue breakdown, causing bleeding, muscle weakness, impaired wound healing, and nervous system disorders.  It is believed that megadosing of vitamin C for extended periods of time, then drastically reducing the dose or going off cold turkey may lead to a condition known as rebound scurvy.  Rebound scurvy is believed to occur when the body continues to excrete large amounts of vitamin C when megadoses are no longer being supplemented.  Although, very few cases of rebound scurvy have been reported, and information about the cases have not been well-documented. 

            Excessive vitamin C intake is also known to displace vitamin B12 from the body. Vitamin B12 is essential for the maturation of blood cells. Deficiencies of B12 lead to a problem known as macrocytic anemia. This condition leads to the formation of abnormally large red blood cells, with impaired ability to carry oxygen. Decreased oxygen levels may cause fatigue, muscle weakness, shortness of breath, and possibly heart arrhythmias. 

            Macrocytic anemia also leads to the formation of abnormally large white blood cells with altered nuclei. White blood cells are an important component of the immune system. Therefore, macrocytic anemia from B12 deficiency may impair immune function. 

            B12 deficiencies may cause nerve damage leading to nerve pain and numbness, or loss of some senses. Mental disturbances may also develop including depression, dementia, paranoia, irritability, and delirium. 

            Vitamin C is a water soluble compound, which can be easily flushed from the body.  Although, vitamin C is a relatively unstable compound, and a portion of excess ingested vitamin C breaks down into oxalic acid in the body. 

            Oxalic acid is beneficial to the body as well as detrimental. As vitamin C breaks down in to oxalic acid, the oxalic acid actually serves as an antioxidant to the vitamin C helping to prevent oxidative destruction of the vitamin C. On the other hand, oxalic acid can bind with minerals forming insoluble oxalates. Of particular importance is calcium oxalate, which can form kidney stones. Studies have shown that oxalic stones, which make up 80% of kidney stones, only formed in people with kidney diseases, but not in healthy individuals at doses of 200mg daily. At 1,500mg daily intake there was only a tiny rise in the incidence of oxalic stone formation. It is believed that the insignificant rise is due to the fact that vitamin C is poorly absorbed by the body. Therefore, the higher levels of vitamin C are not being absorbed, and therefore are not converted in to oxalic acid. 

Oxalic acid also binds with the electrolytes sodium and potassium, and the mineral magnesium. Among other functions of sodium and potassium is the regulation of heart rate. Magnesium serves a multitude of important functions including maintaining normal blood pressure, proper muscle function; including the heart, preventing muscle cramping, and insulin production. 

            Oxalic acid is an irritant to the urinary tract. Irritation of the urinary tract from oxalic acid can lead to urinary tract infections in sensitive individuals. 

            There is also concern that vitamin C may cause uric acid stones to form from excess excretion of uric acid. Acidification of the urine with vitamin C increases the ratio of uric acid to the more soluble sodium urate. For this reason, treatment of uric acid stones includes alkalinizing the urine with sodium bicarbonate (baking soda) or calcium citrate to increase sodium urate formation. 

            Excessive levels of vitamin C are contradicted in people suffering from kidney stones, gout, cirrhosis, kidney diseases, and certain other disorders. 

            Safety studies at doses of 200 to 1,500mg daily are conflicting. Safety studies of extremely high doses, up to 20,000 have not been done. Therefore I recommend not exceeding 2,000mg daily for healthy individuals. Normally, I recommend 500mg 3 times daily for most individuals. Slightly higher levels are recommended for smokers, individuals under a lot of stress, stimulant users; including caffeine (coffee, tea, guarana, kola nut, etc.), and those taking medications known to deplete vitamin C, such as Prednisone. 

            A major concern of taking excessive doses of vitamin C is the fact that large amounts of vitamin C can block copper absorption.  Copper serves various functions in the body including production of the antioxidant, anti-inflammatory, and immune stimulating enzyme copper superoxide dismutase.  Copper is essential for the formation of collagen and elastin, which give strength and elasticity to the tissues.  Copper also plays a role in the formation of neurotransmitters for proper nerve function. As a factor in the production of melanin, copper helps to prevent graying of the hair. In addition, copper helps to maintain proper levels of blood lipids (fats), including cholesterol.  

            Decreased copper levels can lead to decreased collagen and elastin synthesis. This in turn leads to bone loss, blood vessel weakness, poor wound healing, gum disorders, tendon and ligament weakness, cartilage disorders, bruising, and wrinkles.  Disorders such as emphysema and diverticulitis also involve loss of elastin in tissues. 

            The risk of heart disease increases with copper deficiencies.  This is most likely due to weaker arterial walls, combined with increased inflammation, increased oxidative damage, and elevated cholesterol levels. 

            Vitamin C is often touted as an immune stimulant, although excessive levels may have the opposite effect. The enzyme copper superoxide dismutase (cu-SOD) produces hydrogen peroxide in response to infections. Hydrogen peroxide serves various functions, including activation of the immune system’s white blood cells. White blood cells fight infections, and cancer cells within the body. Therefore, declining levels of cu-SOD can have an adverse effect on the immune system. 

            Inflammation has been shown to be a major contributor to the formation of cancers. Another primary function of cu-SOD is to reduce inflammation. Copper therefore may play a crucial role in other inflammatory diseases as well, such as colitis, and arthritis. 

            As an antioxidant, cu-SOD helps protect cells from free radical damage. The body requires free radicals, such as hydrogen peroxide. Excessive levels of free radicals have been implicated in various diseases though, including cancer. 

            Hemoglobin requires copper for its production. Therefore, copper deficiencies can lead to anemia. 

            Copper is essential for the formation of thyroid hormones. Copper deficiencies lead to hypothyroidism, although excessive levels suppress thyroid function. This is especially true if zinc deficiencies are present since zinc promotes thyroid function. Note that excessive levels of zinc can over stimulate the thyroid. 

            As a cofactor in neurotransmitter production, copper deficiencies can lead to depression. High copper levels though have also been linked to depression, as well as schizophrenia, ADHD symptoms, and other neurological disorders. 

            The brain and spinal cord contain some of the highest levels of copper in the body. Copper is not only essential for the formation of neurotransmitters, but also for myelin, which insulates nerves so they do not “short circuit”. 

            Interestingly, the brain contains about 10 times the level of vitamin C as found in the blood. Vitamin C actually has to be oxidized to cross the blood-brain barrier. Oxidation converts the vitamin C in to dehydroascorbic acid, which allows it to be transported in to the brain through sugar receptors. There the dehydroascorbic acid is converted back in to ascorbic acid, commonly known as vitamin C. Here the vitamin C helps prevent damage to the myelin from free radicals, and aids in the conversion of dopamine to norepinephrine. 

            Copper is essential for the proper regulation of histamine throughout the body. High levels of histamine can lead to allergic responses, including asthma. In the brain, histamine plays roles in mood, behavior, libido, addictions, and sleep and wake cycles. 

Despite all the benefits of copper, excess levels of copper can be dangerous. Copper supplementation is not recommended in most cases, although it should be combined with zinc if supplementing zinc. The common ratio of zinc to copper in supplements is 50mg zinc to 2mg copper. Women with excessive levels of estrogen would probably benefit more by taking zinc, but not copper. Estrogen increases copper levels, and zinc antagonizes copper helping to reduce the risk of copper toxicity.

            Copper, which is displaced by excess vitamin C, is essential for the formation of hemoglobin, which carries oxygen to the tissues, and removes carbon dioxide.  Iron is also essential for the formation of hemoglobin, and iron absorption is increased by vitamin C.  This all brings up an interesting problem.  If iron levels are increased by improved absorption from vitamin C, but hemoglobin cannot be formed due to lack of copper, what happens to all the iron being absorbed? 

            As with copper, and vitamin C, iron is essential for the body and serves various purposes.  Although, as with copper and vitamin C, excess levels of iron can be dangerous. And since the body has no efficient way of ridding itself of excess iron, iron levels may easily build up to toxic levels. 

            As iron accumulates in the body it is primarily stored in organs and glands, where it can lead to organ failure and glandular damage.  The heart, liver, and pancreas are at the greatest risk of damage and failure from iron overload. 

            Side effects of iron overload include heart disorders, diabetes, cirrhosis of the liver, adrenal insufficiency, hypothyroidism, parathyroid damage resulting in low blood calcium, pituitary gland dysfunction, atrophy of the testes and ovaries, nervous system damage and disorders, arthritic disorders, graying or bronzing of the skin, and decreased energy levels. Numerous microbes, and protozoa, thrive with high iron levels.  These include Candida, Listeria, Chlamydia, Salmonella, Plasmodium, Staphylococcus, Streptococcus, Cryptococcus, Campylobacter, Pseudomonas, Helicobacter pylori Escherichia coli, and numerous others.  

Iron overload is also known to increase the risk of various cancers including liver cancer, Kaposi's sarcoma, breast cancer, melanoma, and colon cancer.  The increased risk of cancer is probably due to the increased activity of cancer pathogens.  For example, human papilloma virus has been linked to several cancers including breast cancer.  Human herpes virus type 8 has been linked to the viral form of Kaposi's sarcoma.  Liver cancer has been linked to hepatitis viruses, and aflatoxins from the fungus Aspergillusniger.

Arthritis may occur from iron overload due to two factors.  Oxidative destruction can lead to join damage.  In addition, certain forms of arthritis are triggered from pathogens.  For example, rheumatoid arthritis has been linked to an infection with a form of Chlamydia bacteria.

Heart disease, due to iron overload, is generally believed to result from oxidative damage to the arterial lining, and to the heart muscle itself.  There may be a secondary factor though.  Scientists have found a link between Chlamydia bacteria and arterial sclerosis, which may lead to arrhythmias, angina, and heart attack. 

Excess of levels of iron have also been found in the brains of Alzheimer's patients.  As with the excessive aluminum levels found in the brains of Alzheimer's patients, that excessive iron levels have not been proven to be a cause of Alzheimer's.  Although, it is hypothesized that the excessive level of iron may be causing oxidative damage to the brain, leading to Alzheimer's disease.