AICR's Cancer Research Update

Issue 40 — April 7, 2010

Also in this issue:

  1. Drinking Alcohol and Eating Badly
  2. The Sixth Sense
  3. Multivitamins and Breast Cancer Risk
  4. In Brief: Peach Genes
Dale Buchanan Hales

Scientist in the Spotlight: Dale Buchanan Hales

Flaxseed, Hens, and Ovarian Cancer

The idea that omega-3 may help to prevent ovarian cancer was spawned years ago while Dale Buchanan Hales, PhD, was picking up a carton of eggs at the grocery store. Now, in a study built upon AICR support, Dr. Hales has found that a flaxseed-enriched diet may decrease the severity of ovarian cancer in hens. The study, although preliminary, may eventually lead to human studies with the goal to lengthen survival for women diagnosed with ovarian cancer.

The study was published in the February issue of Gynecologic Oncology.

Currently, over half of ovarian cancer survivors die within 5 years of diagnosis. The disease is often dubbed 'the silent killer' because women can have it for years without apparent symptoms.

Slowing the Spread

Hens are the only animals besides humans known to spontaneously develop ovarian cancer, and at a relatively high rate, making them an ideal model to study this disease. Hens producing the omega-3 enriched eggs sold in grocery stores feed on a flaxseed-enriched diet, and spotting the eggs gave Dr. Hales an idea. “I found the research was all about the eggs and the hens relative to the eggs,” said Dr. Hales. “We wanted to find out what the diet was doing to the health of the hens.”

In the study, the scientists randomly divided 387 healthy hens into two groups. One group was fed a 10 percent flaxseed-enriched diet comparable to approximately 10 tablespoons of ground flaxseed in a human diet, an amount beyond what is generally studied in humans. The control group was fed a standard diet equal in calories.

The hens were 2.5 years old, roughly equivalent to the age of a woman entering menopause.

“We wanted to find out what the diet was doing to the health of the hens.”

After one year, almost a quarter of all the hens developed ovarian cancer. Yet the flaxseed-fed hens had significantly more early-stage tumors compared to the late-stage tumors of the control group. The tumors of the flaxseed-fed hens were confined to the ovaries, compared to the control hens whose tumors had metastasized. There was no significant difference in cancer incidence between the groups.

A one-year study may not be enough time to test the cancer protective effects of flaxseed. Hales is currently in the middle of a large, four-year study to determine if long-term flaxseed-enriched diets will reduce the incidence or severity of ovarian cancer.

"It was AICR that enabled us to start our flaxseed research in the first place, and for that I’m grateful," noted Hales.

Possible Mechanisms

Flaxseed is the richest plant source of one kind of omega-3 fatty acid, alpha-linolenic acid (ALA), which has shown promise in protecting against heart disease and some cancers. Flaxseed also contains lignans, a group of phytoestrogens that act as weaker versions of estrogen in the body.

Studies suggest that lignans may alter estrogen metabolism and prevent tumor growth. Omega-3 may inhibit the production of prostaglandins, substances that stimulate cancer growth and inflammation. Research suggests that inflammation plays a key role in the development of cancer.

Adding (Some) Flaxseed to a Diet

Incorporating flaxseed in the diet may provide health benefits, but research is too limited to suggest consuming high amounts. In general, research on flaxseed and cancer in human studies falls within amounts equivalent to 1 to 4 tablespoons daily.

According to the National Institutes of Health, studies remain inconclusive as to flaxseed’s effectiveness in humans. Also, there are few studies showing that high amounts of flaxseed such as those used in this study are safe. Earlier research by Dr. Hales found that hens fed a 20 percent flaxseed-enriched diet developed liver damage, which is why they lowered the amount.

Note: Cancer survivors or others on medication should consult their physician before consuming flaxseed. Flaxseed may slow or decrease the absorption of certain medications and supplements.

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PeachesIn Brief

For the first time, scientists have sequenced the DNA of a peach tree, a finding that could have far-reaching implications for the future of peaches and similar types fruits in general. Peaches contain many compounds studied for their cancer-fighting properties, such as carotenoids, vitamin C, and beta-carotene, and knowing the tree’s DNA may help scientists develop varieties of fruit with different health promoting properties.

The research is now available online.

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alcoholic drinksResearch Roundup

Drinking Alcohol and Eating Badly

A new study suggests that alcohol drinkers are less likely to eat whole grains and fruit and they are more likely to eat unhealthy foods high in fat and sugar. The findings, published in the April issue of the Journal of the American Dietetic Association, raise questions on whether the strong link between heavy alcohol use and chronic health diseases, such as heart disease and cancer, is entirely due to alcohol use alone or if poor eating habits may play some role.

In the study researchers collected drinking and dietary data from approximately 8,100 men and 7,700 women who had participated in a major national survey (NHANES). Among both sexes, energy intake increased and diet quality declined with increasing alcohol.

For men, those who once or currently drank consumed significantly less total fruit compared to those who never drank. Current drinkers also consumed more calories from solid fats and added sugars. Among women, total diet quality was lower among current drinkers than the women who never drank; the alcohol drinkers consumed less whole grains and milk.

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The Sixth Sense

Butterand OilsFirst there were four known tastes people could sense – sweet, salt, sour, and bitter – then in the early 2000s came the fifth sense, umami, the savory taste in many high- protein foods. Now, Australian scientists report they have identified a sixth sense the human tongue can detect: fat. Published in this month’s issue of the British Journal of Nutrition, the study suggests that understanding this sixth sense may hold a key to reducing the rate of obesity.

In the first part of the study, scientists determined at what levels participants could detect three types of fatty acids common in foods: oleic, linoleic, and lauric. The 31 participants drank several preparations of milk, with various concentrations of the fatty acids and with no fat, and identified when they could taste the fatty acid.

In the study’s second part, a group of participants filled out a two-day food diary and were identified as having a high or low taste threshold for fat. Those who were could detect the fatty acid in low concentrations were more prone to detect small differences in fat content. Researchers found that those with a high sensitivity to the taste of fat consumed fewer fatty foods and had lower BMIs than those with a low sensitivity to fatty acids.

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SupplementsMultivitamins and Breast Cancer Risk

Women who take multivitamins may face a higher risk of breast cancer, suggests a new study published in the American Journal of Clinical Nutrition.

In the study of approximately 35,000 Swedish women aged 49 to 83, about one-quarter reported that they took multivitamins. The data was collected in 1997 and the women were all cancer-free. After a mean follow-up of almost 10 years, the study analysis found that women who reported taking multivitamins (7 or more tablets per week) were 19 percent more likely to develop breast cancer than those who did not take multivitamins. There was no link between the type of breast cancer and the increased risk.

The study could not account for the type of multivitamin or many other factors that may influence risk. Previous studies have resulted in conflicting findings on multivitamin use and breast cancer risk; more research is needed, note the authors.

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