Taking Vitamins C, E and Beta-Carotene

While the role of antioxidants in preventing cancer has received much attention, some researchers think they may also play a significant role in protecting healthy cells during cancer treatment itself.

Giving cancer patients high doses of beta-carotene and vitamins C and E may protect their healthy cells from the onslaught of tumor-killing treatments like chemotherapy and radiation, say Denver researchers.

Further, they contend, the antioxidants may bolster the effectiveness of standard cancer therapy.

No studies on humans back up these ideas, but in animal studies and experiments on cancer cells, antioxidants have shown promise, according to a report in the Journal of the American College of Nutrition.

Kedar Prasad, lead author of the report, said more definitive data will come from a current trial studying the effects of antioxidant treatment on cancer patients.

Already, though, Prasad and his colleagues at the Center for Vitamins and Cancer Research at the University of Colorado Health Sciences Center believe antioxidants may become an important cancer weapon.

Antioxidants have been studied as disease fighters because they prevent cell damage from oxygen molecules known as free radicals, which are produced during normal metabolism.

One recent study suggested that an antioxidant found in tomatoes might explain the link between tomato consumption and lowered risk of some cancers.

In their experiments, Prasad and colleagues found that high doses of multiple antioxidants not only protect normal cells during cancer treatment, but can also help fight back tumors. Together with diet and lifestyle changes, antioxidants may improve standard cancer therapy, they reported.

Another antioxidant researcher, however, thinks Prasad's team is jumping the gun. While the new report is "exciting and provocative," it really only forms the base for further research, said Jeffrey Blumberg, a professor of nutrition at Tufts University in Boston.

"I think antioxidants are terrific," Blumberg said, noting that there is "compelling" data on antioxidants' benefits for the heart and eyes. Evidence of the vitamins' link to cancer prevention is not as strong, he added.

According to Prasad, antioxidants have garnered little enthusiasm among oncologists partly because they worry that the vitamins might actually protect cancer cells from free radicals generated during chemotherapy and radiation therapy.

"But," said Prasad in response, "these vitamins are very selective." Normal cells, he explained, are programmed to pick up a maximum level of the vitamins and nothing more, which protects them from an antioxidant overdose.

Cancer cells, however, accumulate the vitamin to levels that may be high enough to stunt their growth or even kill them, according to Prasad.

Based on their experiments, as well as their observations of some cancer patients receiving antioxidants, Prasad's team recommends that standard cancer treatment include doses of vitamin C, vitamin E and beta-carotene.

But making cancer-treatment recommendations at this point constitutes a big leap, according to Blumberg. Experiments on cell cultures, he said aren't enough to provide a "rational scientific basis" for such recommendations.

Still the Colorado team's results show antioxidants may have a role beyond just the prevention of disease, Blumberg said. Clinical trials, he added, should explore the possibility. SOURCE: Journal of the American College of Nutrition

Meat Compound May Not Be Carcinogenic

A compound found in cooked meat may not be the "missing link" connecting high red meat consumption with increased cancer risk, according to new research.

"Intake of heterocyclic amines, within the usual dietary range... is unlikely to increase the incidence of cancer," wrote Dr. Katarina Augustsson and colleagues of the Karolinska Institute in Stockholm. Their findings were published in the British medical journal The Lancet.

Numerous studies have suggested an association between high dietary consumption of red meat and an increased risk of cancer.

Heterocyclic amines-found in the charred parts of meat and fish-emerged as compounds that may be responsible for this increased risk.

The Swedish team focused their research efforts on heterocyclic amines. They interviewed nearly 1,600 adult Swedes regarding their everyday consumption of meat dishes rich in these compounds. About two thirds of those interviewed had a history cancer, while the remaining third were healthy "controls."

Augustsson's team found no consistent relationship between heterocyclic amine intake and cancer risk. They pointed out that their results showed that rates of colon and rectal cancer actually decreased as heterocyclic amine intake rose.

On the other hand, high heterocyclic amine consumption was associated with a slight rise in the overall incidence of bladder cancer. Risk for kidney cancer did not appear to be affected by heterocyclic amine intake.

The authors concluded that ingestion of the meat compound is "not a major cause of the cancers we investigated."

They speculated that other suspected carcinogens in red meat-including polycyclic aromatic hydrocarbons or nitrosamines-might help trigger human cancers.

In an editorial, Dr. David Forman of the University of Leeds, UK, cautioned that the Swedish findings do not altogether rule out heterocyclic amines as possible carcinogens.

He pointed out that individual humans metabolize these compounds at different rates and in different ways.

"The possibility remains that (heterocyclic amine) exposure... is a risk factor for cancer but only in individuals with the appropriate genetic background," he explained.

SOURCE: The Lancet
 

[Table of Contents] [ Archived Issues / Search] [ The Breast Center]