Ginseng, flaxseed may fight cancer, but shark cartilage worthless, studies say
But a big Canadian-U.S. study proved shark cartilage worthless against lung cancer, and doctors said people should not take it.
The research was reported Saturday at an American Society of Clinical Oncology conference.
What is American ginseng? According to information offered by the University of Maryland Medical Centre, the American ginseng plant has leaves that grow in a circle around a straight stem. Yellowish-green umbrella-shaped flowers grow in the center and produce red berries. Wrinkles around the neck of the root tell how old the plant is. This is important because American ginseng is not ready for use until it has grown for four to six years. American ginseng is very expensive and is now being grown on farms in order to protect the wild American ginseng from over-harvesting.
American ginseng products are made from ginseng root and the long, thin offshoots called root hairs. The main chemical ingredients of American ginseng are ginsenosides and polysaccharide glycans (quinquefolans A, B, and C). American ginseng seems to be more relaxing than Asian ginseng, which may have stimulating effects.
American ginseng (dried) is available in water, water-and-alcohol, or alcohol liquid extracts, and in powders, capsules, and tablets. American ginseng is available with other herbs in several combination formulas.
How to take it
- This herb is not recommended for use in children unless under the supervision of a qualified health care provider.
- Fresh root: 1 – 2 g, once daily for up to 3 months
- Dried root: 1/2 – 2 g, chew and swallow once daily
- Tincture (1:5): 1 – 2 teaspoonfuls, 1 – 3 times daily
- Fluid extract (1:1): 1/4 – 1/2 teaspoonfuls, 1 – 3 times daily
- Standardized extract: 100 – 200 mg, 1 – 3 times daily, standardized to contain 4 – 5% ginsenosides
Reported side effects of taking ginseng include:
- High blood pressure
- Breast pain
- Vaginal bleeding
To avoid low blood sugar (hypoglycemia), even in people who do not have diabetes, you should take American ginseng with food.
People with hypertension should not take American ginseng products without specific guidance and instruction from a qualified health care provider. At the same time, people with low blood pressure as well as those with an acute illness or diabetes (because of the risk of a sudden drop in blood sugar), should use caution when taking ginseng.
The safety of taking American ginseng during pregnancy is unknown. Therefore, it is not recommended when pregnant or breastfeeding.
American ginseng should be discontinued at least 7 days prior to surgery. American ginseng can lower blood glucose levels and, therefore, create problems for patients fasting prior to surgery. In addition, American ginseng may act as a blood thinner, thereby increasing the risk of bleeding during or after the procedure.
The ginseng and flaxseed studies are small and preliminary, and specialists warned against making too much of them because the substances tested are not the same as what consumers find on store shelves.
But the results suggest that some herbal remedies eventually may find niches for treating specific cancers, symptoms or side effects. Americans spend millions on these products, which are not approved by the federal Food and Drug Administration, even though no good studies confirm the benefits they tout.
“One of the most common things patients ask me is about these things they have snookered away in their purses” and medicine chests, said Dr. Bruce Cheson, a cancer specialist at Georgetown University Hospital. “They’ll come in with big bags of this stuff.”
Some “natural” remedies such as laetrile or high doses vitamin C proved not helpful and even harmful for cancer patients once they were scientifically studied, he noted. Some keep chemotherapy from working as it should.
“Just because it is a vitamin or a leafy green does not ensure it does not have some harmful effects,” Cheson said.
Herbal products vary widely in their purity and the amount and type of active ingredients. These three federally funded studies used standardized compounds so they could say with some certainty whether they have any effect.
Debra Barton, a research nurse at the Mayo Clinic in Rochester, Minn., tested powdered, four-year-old Wisconsin ginseng root, which is different from Asian ginseng and other varieties commonly sold, to treat the extreme tiredness that most people suffer from cancer or its treatment.
She randomly assigned 282 people with breast, lung, colon and other forms of cancer to take either 750, 1,000 or 2,000 milligrams of ginseng or dummy capsules daily for eight weeks. Neither the participants nor the researchers knew who received what.
One-fourth of those on the two highest doses said their fatigue was moderately or much better, compared with only 10 per cent of those on the low dose or dummy pills.
Results are promising, but it is too soon to recommend that people use ginseng, Barton said. A better idea is exercise, the one treatment already shown to help cancer fatigue, she said.
The flaxseed study was aimed at fighting prostate cancer, not treating a side effect. The edible seed has been used for hundreds of years in cereals and breads and is high in beneficial omega-3 fatty acids and in lignan, a substance that can affect hormone levels and perhaps squelch their cancer-promoting effects.
Four groups of about 40 men who were scheduled to have their prostates removed three weeks later were assigned to get either 30 grams of powdered flaxseed, a low-fat diet, both or neither until their surgery.
After the men’s prostates were removed, researchers found that tumours had been growing 30 to 40 per cent slower in the two groups taking flaxseed, based on how quickly cells were multiplying. Low-fat diets had no effect on this, said Wendy Demark-Wahnefried of Duke University Medical Center, who led the study.
“Our findings are compelling but they’re preliminary,” she cautioned.
But several doctors said flaxseed is nutritious and seems to have little downside other than a sawdust-like consistency, since it must be used ground or powdered because it has an inedible hull or coating.
Scientists plans to study flaxseed on men with prostate cancer that comes back after initial treatment, and Canadian scientists also are testing it for breast cancer, she said.
The shark cartilage study was done because Congress ordered it. Some very small early studies suggested high doses of it might extend survival of people with advanced cases of non-small cell lung cancer, the most common form of the disease.
Dr. Charles Lu of the University of Texas M.D. Anderson Cancer Center in Houston tested Neovastat, a shark cartilage liquid extract that the Canadian company Aeterna-Zentaris was trying to develop as a regular pharmaceutical product.
All 379 people in the study, which was done throughout Canada and the United States, were given standard chemotherapy and radiation. Half also were given shark cartilage twice a day.
After about four years there was no difference in survival, which averaged 15 months for both groups.
On the Net:
Cancer meeting: www.asco.org
Cancer society: www.cancer.org
National Center for Complementary and Alternative Medicine: www.nccam.nih.gov
Ginseng Board of Wisconsin: www.ginsengboard.com