Many cancer patients augment conventional medical treatment with complementary medicine, such as nutritional or herbal supplements. The newest research and decades of successful clinical use show that some of these natural treatments work very effectively to fight cancer and reduce side effects.

Here are the best science-based complementary treatments for cancer. It’s usually fine to take several of these supplements simultaneously, but be sure to talk to your doctor first. For help finding an integrative practitioner, go to http://nccam.nih.gov/health/practitioner.

ANTIOXIDANTS

Cancer specialists often advise patients not to take antioxidant supplements, such as vitamin A or vitamin E, during chemotherapy and radiation treatments. Reason: One way chemotherapy and radiation destroy cancer cells is by causing oxidative stress. According to one theory, antioxidants may be counterproductive because they might have the ability to protect against this oxidative damage.

But new scientific research shows that the opposite is true — antioxidant supplements aren’t powerful enough to counter chemotherapeutic medicines or radiation, but they can reduce the side effects of those treatments and also may battle tumors and extend life.

Recent study: Researchers from the University of Illinois at Chicago and the Institute for Integrative Cancer Research and Education analyzed 19 studies involving 1,554 cancer patients who took antioxidants during chemotherapy. They concluded that most cancer patients are better off using antioxidants in conjunction with chemotherapy and radiation than not using them.

Typical doses…

Vitamin A. 7,500 daily international units (IU), which should only be taken under a doctor’s supervision — patients should have their liver enzymes monitored on an ongoing basis.

Vitamin E. 400 IU daily, taken under a doctor’s supervision (patients should have their platelet counts monitored). It’s best to divide the dose, taking half in the morning and half in the evening. Ideally, take it on an empty stomach.

ASTRAGALUS

The herb astragalus has been used in traditional Chinese medicine for thousands of years. Scientific studies show that it strengthens the immune system, increasing the activity of cancer-fighting cells and inhibiting the activity of immune cells that increase inflammation and thereby worsen cancer. Research shows that the herb also can boost the power of some types of chemotherapy.

Recent study: Researchers from the School of Public Health at the University of California, Berkeley, analyzed 34 studies involving 2,815 patients with non-small-cell lung cancer who were treated with chemotherapy alone or who were treated with chemotherapy and astragalus. The patients taking astragalus had a 33% lower risk for death after 12 months and a 24%-to-46% better tumor response than those not taking the herb.

Typical dose: 750 milligrams (mg) to 2,500 mg a day of astragalus extract.

GINSENG

Extracts from the root of this herb often are used as a natural stimulant — to boost mental and physical energy, improve athletic performance and relieve fatigue. Ginseng also may boost energy in cancer patients.

Recent study: Doctors from the North Central Cancer Treatment Group at the Mayo Clinic gave either a placebo or ginseng — at daily doses of 750 mg… 1,000 mg… or 2,000 mg — to 282 cancer patients. Those taking 1,000 mg or 2,000 mg of ginseng had more energy and vitality and less fatigue. Those taking 750 mg or a placebo had no such improvement. The patients taking the higher doses of ginseng also reported greater physical, mental, emotional and spiritual well-being.

Typical dose: 500 mg to 1,000 mg twice daily of American ginseng (not Asian red ginseng). Medical supervision is needed for the higher dosage, particularly if you are taking blood-thinning medication.

GLUTAMINE

Chemotherapy can damage the mucous lining of the digestive tract, which stretches from the inside of the mouth to the rectum. One common result is oral mucositis (OM), a condition in which the mucous lining of the mouth and throat becomes inflamed, painful, ulcerated and prone to infection. The amino acid glutamine fuels the daily maintenance of the mucous lining of the digestive tract — and supplemental glutamine helps limit or stop its destruction by chemotherapy.

Recent study: Researchers at the University of Connecticut Health Center gave either glutamine powder or a placebo to 326 cancer patients undergoing chemotherapy who were developing OM. Those taking glutamine experienced a significant reduction in the severity of the condition compared with those taking the placebo. In fact, many of those taking glutamine didn’t develop OM at all during their second cycle of chemotherapy.

Typical dose: 5 grams (g) to 10 g, twice daily.

OMEGA-3 FATTY ACIDS

Chronic inflammation is known to fuel the growth of tumors. Omega-3 fatty acids, nutrients abundant in fish oil and flaxseed, are potent anti-inflammatories that slow tumor growth and shrink tumors in animal studies. Recent research shows that omega-3 fatty acids may do the same for men with prostate cancer.

Recent study: Researchers at Duke University Medical Center, the University of Michigan and the University of North Carolina studied 140 men with prostate cancer who were scheduled to undergo prostate surgery in 30 days. They divided the men into four presurgical groups — some took 30 g (about one ounce) of ground flaxseed daily… some ate a low-fat diet and took the flaxseed… some just ate a low-fat diet… and a control group used none of the regimens. After the surgery, researchers found that the tumors of the men who took flaxseed had grown more slowly — at a 30%-to-40% slower rate than those of the other men. The men mixed the ground flaxseed in drinks or sprinkled it on yogurt and other foods. The study was reported at the 2007 annual meeting of the American Society of Clinical Oncology.

Typical dose: One ounce of ground flaxseed… or 3 g of fish oil.

ACUPUNCTURE

Acupuncture is a healing technique from traditional Chinese medicine. An acupuncturist inserts tiny needles into the skin along meridians (energy channels in the body) in order to restore and enhance chi, the fundamental force of health and well-being.

Recent study: Doctors at the Osher Center for Integrative Medicine at the University of California, San Francisco, studied 138 cancer patients undergoing surgery, dividing them into two groups. One group received acupuncture and massage after surgery, along with standard care, such as pain-relieving medications. The other group received standard care only. The acupuncture and massage group had 58% less postsurgical pain and less depression, reported the doctors in the March 2007 issue of Journal of Pain and Symptom Management. It’s hard to tell specifically what role acupuncture played and what role massage played, but other studies that look at acupuncture and massage alone show that each has benefits, including reducing surgical pain.

Other studies show acupuncture may help prevent or relieve chemotherapy-induced nausea and fatigue… chemotherapy-induced decrease in white blood cell count… radiation-induced dry mouth… shortness of breath… and insomnia and anxiety.