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Orthomolecular Medicine

Other common name(s): megavitamin/megamineral therapy, nutritional medicine

Scientific/medical name(s): none


Orthomolecular medicine is the use of high doses of vitamins, minerals, or hormones to prevent and treat a wide variety of conditions. The doses are well above the recommended daily allowance (RDA) and may be used along with special diets and conventional treatment.


Available scientific evidence does not support the use of orthomolecular therapy for most of the conditions for which it is promoted. However, vitamins, minerals, and other supplements have been and continue to be studied to determine whether they can help or prevent many types of illness. Although some supplements have been shown to help certain conditions, a few have unexpectedly proven to be harmful. At this time, eating nutritious foods is the best proven strategy to get the vitamins, minerals, and nutrients that are needed for good health.

How is it promoted for use?

Orthomolecular medicine is promoted to help people with depression, schizophrenia, and other psychiatric illnesses; Parkinson’s disease; shingles; irritable bowel syndrome; alcoholism; colds; heart disease; hay fever; pneumonia; bruises; acne; eczema; bug bites; cold sores; chronic fatigue syndrome; and many other health problems. Supporters believe poor nutrition and refined foods are at the root of many of these illnesses. Proponents of this therapy believe that conventional medicine is foreign to the body and potentially harmful. They prefer vitamins, minerals, enzymes and other substances they consider to be "natural."

What does it involve?

Depending on the diagnosis, high doses of vitamin C, niacin, or other vitamins and minerals may be recommended. These are usually taken by mouth. The patient may be put on a diet free of refined sugar and white flour. The diet may follow other specific guidelines. In some cases, the practitioner may perform hair analysis, blood tests, or urine tests to learn the levels of certain minerals or vitamins in the person’s body.

What is the history behind it?

The concept of orthomolecular medicine dates back to the early 1950s. Nobel Prize winner Linus Pauling, PhD, coined the term in 1968. Proponents believe that taking large doses of vitamins or nutrients could correct "biochemical abnormalities" and thereby reverse a wide variety of conditions such as alcoholism, allergies, arthritis, asthma, cancer, depression, epilepsy, heart disease, high blood pressure, hyperactivity, migraine headaches, mental retardation, and schizophrenia.

What is the evidence?

So far, most studies have shown that taking supplements is not as effective in cancer prevention as eating the foods that contain the vitamins or minerals. This may be because foods have helpful nutrients other than those being studied, because nutrients have different effects when combined than when consumed individually, or because of other factors.

In some cases, supplements are effective in correcting deficiencies. It has long been known, for instance, that iron supplements can help iron-deficiency anemia and that vitamin C supplements can correct scurvy. Both are examples of diseases caused by a deficiency of a vitamin or mineral. A few vitamins and minerals have been shown to have physical effects beyond correcting deficiencies. For example, supplements of nicotinic acid (a form of niacin, or vitamin B3) have been shown to help lower cholesterol levels in some people and have become part of standard medical treatment.

Research is still going on to learn more about the use of supplements to treat or prevent specific health conditions, including cancer.

Some studies have looked at the role of several antioxidants, alone or in combination, in the prevention and treatment of cancer and other diseases. Antioxidants are compounds that block the action of activated oxygen molecules called free radicals, which can damage cells. They are thought to reduce the risk of some types of cancer. Examples of antioxidants are vitamin C, vitamin E, and beta carotene (a precursor of vitamin A). Certain trace minerals such as selenium, copper, and zinc also act as antioxidants. Other studies have looked at minerals in the body such as potassium, magnesium, and calcium.

The antioxidants vitamin E, vitamin C, beta carotene, selenium, and zinc were given to French men and women over a 7-year period. Others were given a placebo over that same time period. The men who took the supplement combination seemed to have slightly lower cancer risk than those who took the placebo. However, the men began the study with lower levels of antioxidants in their bodies, especially levels of beta carotene and vitamins C and E. This may partly explain why they benefited more. The women who took the supplement had the same cancer risk as those who took the placebo.

A large clinical trial looked at whether beta carotene and retinol (a form of vitamin A) could help reduce cancer and deaths in people who were at high risk of lung cancer because of smoking or asbestos exposure. In 1996, the researchers found that the group receiving the vitamins had a higher risk of lung cancer, heart disease, and death. The study was stopped right away. Researchers continued to follow the groups to determine whether these effects continued beyond the study. The risk of heart disease dropped back to a normal level very quickly, but cancer risk stayed higher for several years.

One 2005 study looked at whether supplements might help prevent side effects of cancer treatment. Canadian researchers gave "natural" vitamin E and beta carotene to people undergoing radiation therapy for head and neck cancers. The researchers found that those who received the vitamins had fewer side effects from treatment. However, later on, those individuals had more recurrences of their cancer. This finding supports older information suggesting that antioxidant supplements taken during cancer treatment may decrease the treatment’s effectiveness.

The HOPE TOO study followed up on patients with diabetes or vascular disease who had been studied in the 1990s. It found that there was no difference in cancer or blood vessel disease in the heart between those who received vitamin E and those who took placebo. Unexpectedly, those who received vitamin E had increased rates of heart failure over those who received the placebo.

Clinical trials using high doses of vitamins have been done for people with mental illnesses. Schizophrenic patients treated with vitamin C or vitamin B6 showed no improvement over those receiving a placebo. Children with attention deficit disorder who received high doses of vitamins C, B3, B5, and B6 showed no difference from those receiving a placebo.

A 2007 review of 68 studies of vitamin supplements concluded that people taking vitamin A and vitamin E supplements had shorter life expectancy than those who did not take these supplements and that vitamin C had no effect on longevity.

As studies continue, researchers are learning from these surprising findings. For example, researchers have found that supplement recommendations cannot be made based solely on observational studies. Nearly all of the large observational epidemiologic studies showed strong links between low intake of beta carotene in foods and higher rates of cancer. However, a subsequent clinical trial found that giving beta carotene supplements turned out to raise cancer risk -- the opposite of what was expected. Also, researchers noted that the effects of some supplements take years to show up and that some effects take years to wear off after the supplements are stopped.

More nutrients are still being studied in controlled clinical trials, such as a study in which trace minerals are given to seriously ill patients to see whether survival is improved. One preliminary study suggests that the antioxidant lutein may help those with macular degeneration, a loss of vision in older people caused by poor circulation to the retina. More research is needed to find out whether this holds true in larger studies.

It is well known that nutrition is important to overall health. Poor nutrition may contribute to illness; for example, obesity is linked to diabetes and heart disease and raises the risk of some cancers. Healthy nutrition may contribute to good outcomes from illness. In one study, for example, women who ate low-fat diets after treatment for estrogen-receptor-negative breast cancer were less likely to have recurrence of their cancer. However, vitamin or mineral supplements have not been proven to cure any type of cancer. Available scientific studies have not shown that orthomolecular medicine can help most of the conditions for which it is recommended.

At this time, it is hard to say how each nutrient or nutrient combination affects a person’s risk of cancer. Studies of large groups of people have shown that those whose diets are high in vegetables and low in animal fat, meat, and/or calories have lower risks for some of the most common types of cancer. However, until more is known about this, the American Cancer Society recommends eating a variety of healthful foods -- with most of them coming from plant sources -- rather than relying on supplements.

While it is best to get vitamins and minerals from foods, supplements may be helpful for some people, such as pregnant women, women of childbearing age, and people with restricted food intakes. If a supplement is taken, the best choice for most people is a balanced multivitamin/mineral supplement that contains no more than 100% of the "Daily Value" of most nutrients.

Are there any possible problems or complications?

These substances may not have been thoroughly tested to find out how they interact with medicines, foods, herbs, or supplements. Even though some reports of interactions and harmful effects may be published, full studies of interactions and effects are not often available. Because of these limitations, any information on ill effects and interactions below should be considered incomplete.

Vitamin A, vitamin D, selenium, iron, magnesium, zinc and other supplements can cause complications if too much is taken. Occasional deaths have been reported from iron or magnesium overdoses, mostly in children. Overdoses of minerals may also cause vomiting, diarrhea, hair loss, rashes, and diseases of the nails. Zinc and molybdenum can cause the body’s copper levels to drop, which may cause anemia and low white blood cell counts. High doses of pyridoxine (vitamin B6) have been linked with reports of pain, numbness in the hands and legs, and trouble walking. Vitamin A overdoses can cause headache, drowsiness, irritability, vomiting, loss of hair and eyebrows, and peeling of the skin. Too much vitamin D can cause poor appetite, nausea, vomiting, weakness, itching, and permanent kidney damage.

Some supplements can raise the risk of cancer or heart disease. In addition, the potential interactions between supplements and drugs and herbs should be considered. Some of these combinations may be dangerous. Always tell your doctor and pharmacist about any supplements and herbs you are taking.

Antioxidant supplements can interfere with chemotherapy or radiation therapy. Patients who are in cancer treatment should consult with a knowledgeable physician before taking vitamins, minerals, or other supplements. Relying on this type of treatment alone and avoiding or delaying conventional medical care for cancer may have serious health consequences.

Additional resources

More information from your American Cancer Society

The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org) or ordered from our toll-free number (1-800-ACS-2345).

Dietary Supplements: What Is Safe?

The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management

Complementary and Alternative Methods and Cancer

Placebo Effect

Learning About New Ways to Treat Cancer

Learning About New Ways to Prevent Cancer


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Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.

Last Medical Review: 11/28/2008
Last Revised: 11/28/2008