Junkfood Science: Christmas Gingerbread

December 23, 2007

Christmas Gingerbread

Tis the season to enjoy wonderful baked cookies, breads and cakes, and the rich aromas and flavors of roasted coffee and holiday roasts. Gingerbread and spice cakes date back to the eleventh century and have long been part of our most cherished Christmas traditions. Recent news, however, is warning that such foods can increase a woman’s risk for cancer. Behind these stories is the return of a scare about foods cooked to golden brownness: the presence of acrylamide. The new Dutch study behind the headlines, however, found no evidence that women need to worry.

Acrylamide 101

Before we look at this study, a brief introduction to acrylamide may be helpful. It’s not some new chemical or inflicted upon us by modern food production or anything. When chefs and homecooks fry, roast and bake foods to achieve those lovely golden brown crusts — called Maillard browning, the result of the reaction between proteins and carbohydrates — acrylamide is one of the molecules formed. As humans, we have been cooking and roasting foods for nearly two million years, according to Harvard University anthropologist Richard Wrangham, and it’s what has enabled the human species to survive because heat makes meats and starches softer and digestible. In other words, humans have been consuming acrylamide, and the thousands of other Maillard molecules identified thus far, since the age of hunters and gatherers.

While acrylamide levels are higher in foods cooked at high temperatures, it’s also found in uncooked foods and even foods stored at room temperature. In fact, the U.S. Food and Drug Administration’s Total Diet Study survey has found acrylamide in forty percent of the foods we eat. It’s also unpredictable, with significant variations even among samples of the same foods. The highest concentrations are in black olives, graham crackers, smoked almonds, cocoa powder, coffee, onion soup, chips, wholegrain cereals and breads, stoneground sesame and rye crackers, sweet potatoes, peanut butter, baked goods, mixed vegetables, chili, sunflower seeds and even prune juice — all foods that can be part of a healthful diet.

You may have heard concerns raised about acrylamide in connection with “greasy” fried potatoes and chips, with baked versions said to be healthier — except that the baked versions can have more than two times the acrylamide as the fried versions. And we eat a lot more breads and wholegrain cereals than fries, exposing us to more acrylamide from these healthful foods.

Singling out any food to eliminate exposure to acrylamide, in fact, makes no sense because there is no food that contributes the majority of our exposure, said David Acheson, a scientist at the FDA’s Center for Food Safety and Applied Nutrition (CFSAN), at the 2003 FDA Food Advisory Committee Meeting on Acrylamide. All foods containing acrylamide also supply important nutrients to our diet and attempting to minimize acrylamide would negatively impact nutrition.

It’s popular to try and scare us about our food by leading us to believe that the mere presence of something means it’s dangerous. But this disregards the basic adage — “the dose makes the poison” — in the spectrum of pharmacology-to-toxicology, where virtually everything (like salt, iron, and even water) can be helpful, neutral or harmful depending on the dose. Detectible amounts of a molecule — in billionths of a gram — does not make it dangerous.

CFSAN has been analyzing our exposures to acrylamide in foods for years. Its latest analysis found the average dietary intake of acrylamide among American children and adults is 0.4 micrograms per kilogram body weight per day, the same as earlier exposure assessments in 2003 and 2004. That’s parts per billion.

But what does that amount mean?

Joseph A. Levitt, as director of CFSAN, explained that current safety guidelines sugesting acrylamide is a “probable human carcinogen” are based solely on animal studies in which cancer risk was observed in rats fed the “maximum tolerated dose” of acrylamide — an amount just below the level the rats would be poisoned to death — at a daily dose for their entire lives starting at 500 micrograms per kilogram of body weight.

To translate that, the average adult man weighing 180.7 pounds and woman weighing 152.3 pounds equates to a lifetime daily dose of 37,500 micrograms of acrylamide. A person would have to consume about 195 pounds of french fries, 142 pounds of graham crackers, or 5,350 one-ounce servings (333 pounds) of cheerios every day, for life, in order to approach the lowest level of cancer risk observed in laboratory rats.

For those concerned about possible harmful effects other than cancers, the 2005 meeting of the Food & Agricultural Organization and WHO Joint Expert Committee on Food Additives reviewed all of the acrylamide research, specifically new toxicology data. Its experts concluded that the amounts in foods are not likely to cause nervous system damage or developmental and reproductive problems in people. The National Toxicology Program Center for the Evaluation of Risks to Human Reproduction convened an Expert Panel in 2004 and reviewed nearly 125 research papers on acrylamide’s reproductive and developmental effects on humans. Its report concurred, concluding:

Considering the low level of estimated human exposure to acrylamides derived from a variety of sources, the Expert Panel expressed negligible concern for adverse reproductive and developmental effects for exposures in the general population.... existing data do not indicate female reproductive toxicity at doses up to 100 ppm [10–14 mg/kg bw/day] in drinking water for rats and 30 ppm (7– 8 mg/kg bw/day) in drinking water for mice.

Despite concerns for toxic level exposures in rodents, there is no evidence that acrylamide in our foods actually causes cancer in humans. It’s not for lack of trying. Since the 2002 discovery of acrylamide in fried foods by Swedish researchers, multiple researchers have attempted to find a link to human cancer ... without success.

An Italian study published in the International Journal of Cancer found absolutely no correlation between consumption of fried potatoes (fries or chips) and histologically confirmed cases of seven major human cancers. Researchers from the Harvard School of Public Health and Karolinska Institute in Sweden conducted the first prospective study to evaluate the association of acrylamide and cancer. They compared the diets of 987 cancer patients and 538 healthy adults over five years. Their results, published in a 2003 issue of the British Journal of Cancer, found that those who ate the most acrylamide — foods containing up to 1,200 micrograms — were at no greater risk for kidney, bladder and large bowel cancer than those who ate less. In fact, the risk of bowel cancer was actually 40 percent lower for the group exposed to the most acrylamide.

After three case-control studies on humans failed to find an association between dietary acrylamide and cancer risk, these same Harvard researchers led by Lorelei Mucci, went on to evaluate acrylamide intakes of more than 43,000 women and track their health status via national health registers from 1991 to 2002. The results, reported in the March 2005 issue of Journal of the American Medical Association found no association between acrylamide consumed in foods and risk of breast cancer. Nor did the researchers find any increased risk of breast cancer among participants who had greater intakes of foods known to contain acrylamide.

Which brings us to this newest study just published in the journal, Cancer Epidemiol Biomarkers Preview.

A link between spice cake and cancers in women?

Researchers, led by Janneke G. Hogervorst of Maastricht University, the Netherlands, used the database from the Netherlands Cohort Study which had enrolled 62,573 postmenopausal women in 1986. At enrollment, the women filled out self-administered food-frequency questionnaires on their diets. Because the questionnaires were open-ended and couldn’t provide necessary details to do detailed analyses on the entire cohort, the researchers used only a subcohort on 2,589 women for this study. Netherlands cancer and pathology registries had been monitored through 1997 and the incidences of cancers among this subcohort recorded.

The researchers selected 16 foods, primarily starches, from the women’s questionnaires. Given the wide range of acrylamide levels in these foods, and the fact that they didn’t know if the foods the women ate were home-made or store-bought, they calculated average acrylamide intakes using estimated levels in those foods. The lesser acrylamide levels from the other of the 150 foods in the women’s food questionnaires weren’t included in this analysis. Among the women, there was no measurable consumption of potato chips or french fries. Most of their dietary acrylamide came from coffee, and spice cake (like gingerbread), followed by cookies.

The researchers divided the estimated daily acrylamide intakes into 5 quintiles, from an average of 0.14 mcg/kg/day in Q1 to 0.53 mcg/kg/day in Q5. Overall, the average acrylamide intakes among the entire cohort were estmated as 0.32 mcg/kg/day. Coffee intakes were similar among all of the women. The spice cakes were the primary source of differences in acrylamide among the quintiles.

The women eating the least (Q1) differed in several ways from those eating the most (Q5): they had the highest levels of education, the lowest rates of family history for breast cancer; significantly lower dietary intakes of calories (about 354 kcal/day), lower intakes of carbohydrates (47 grams/day), slightly lower intakes of saturated fat (53 grams/day), and slightly higher BMIs. They were similar in other confounding factors such as age at menarche, age at menopause, smoking (current, cigarettes/day, years smoked), physical activity, contraceptive use, family history of other female cancers, age and number of children.

The researchers calculated the hazard ratios for endometrial, ovarian and breast cancers, with their computer model adjusting for influential confounding factors.

Breast. There was no association between acrylamide intakes and breast cancer.

Ovarian. The adjusted* hazard ratios among the group of 195 women who developed ovarian cancer was 1.78 among the highest acrylamide intake compared to the lowest. This was of borderline statistical significance, they said. Only when they removed one-third of the women and looked at only those who never smoked did they derive a ratio of 2.22 among the 33 cases in Quintile 5 compared to the lowest intakes.

Endometrial. The adjusted** hazard ratios among the 221 women who developed endometrial cancer was 1.29 among the highest acrylamide intakes compared to the lowest. “There was no statistically significant association between acrylamide as a continuous variable and endometrial cancer, and in the total group of women, there were also no statistically significant associations between quintiles of acrylamide intake and endometrial cancer,” they wrote. When they eliminated one-third of the women who smoked, they derived a ratio of 1.99 at the highest quintile.

All of the findings hug a relative risk of 1.0 (a null finding) with none approaching 3, essential to be considered tenable (above statistical error or random chance), in epidemiological data dredges looking for correlations, as in this study. In other words, this study was a null finding.

Interestingly, in neither of the cancers did the risks among all of the women rise in step with increased acrylamide in their diet (no consistent dose response). Quintile 3, with medium acrylamide intakes, had slightly lower risks for endometrial and ovarian cancers compared to women in Q2 consuming less acrylamide. Q3 also had the lowest intakes of fruits and vegetables and the highest intakes of alcohol.

Separating out a single component of the diet, from the varied diets people eat, and especially basing any conclusions on a single 24-hour snapshot at the beginning of an 11 year follow-up period, problematic data and calculated intakes, adds cautions to attributing risks to acrylamide.

In discussing their findings, the researchers said that this study “provides the first epidemiological indications that dietary acrylamide intake may increase the risk of cancer in humans.” Only one other epidemiological study had looked at a correlation between acrylamide and ovarian cancer and it “showed no association.” This study was the first to find a correlation with endometrial cancer. But they also note that the correlations they found were “considerably higher than the relative risks of dietary acrylamide calculated based on linear extrapolation of the cancer incidence observed in animal studies.” Making such extrapolations is uncertain, however, and “some epidemiologists concluded that epidemiological studies probably don’t have the statistical power to detect an association.”

Given that this study found no tenable correlations, it was creditable that the lead researcher warned in the Telegraph: “It is important that these results are corroborated and confirmed by other studies before far-reaching conclusions can be drawn.”

Dr. Lesley Walker, of Cancer Research UK, also tried to calm fears over a link, the Telegraph reported. She suggested that other factors could have a greater impact on the chances of cancer and this study shouldn’t unduly worry women.

Or does gingerbread cure cancer?

While there is no evidence gingerbread increases risks of cancer in women, some fear foods they believe to be bad for them. Others are just as quick to believe in the curative properties in those very same foods.

This month’s news stories — about the possibility of minute traces of acrylamide in spice cakes and gingerbread giving us cancer — were contrasted by stories saying gingerbread cookies have magical properties to fight cancer in people.

But there is no evidence of that, either.

The source of this second story were two laboratories. South Korean researchers found that (only at) high concentrations of [6]-gingerol (1-[4'-hydroxy-3'-methoxyphenyl]-5-hydroxy-3-decanone), an oleorein found in ginger rhizomes, inhibited the cell adhesion, invasion, motility and activities of MMP-2 and MMP-9 in MDA-MB-231 human breast cancer cell lines. Other researchers at the University of Michigan had presented a poster at last year’s annual meeting of the American Association for Cancer Research revealing that when they dosed ovarian cancer cells with a ginger solution in a test tube, the cells had died. They cautioned that their “results are very preliminary,” hadn’t even been tested in rats yet, and that there is no clinical data to support the notion that any natural product can prevent or cure cancer. People are a long way from test tubes. That hasn’t stopped popular press from jumping a decade or more ahead of the science and reporting gingerbread can combat cancer.

The real concerns and health benefits of gingerbread

The only worries surrounding your Christmas gingerbread need be the decision of whether your gingerbread eaves should have icing icicles and where to put the peppermint wheels. Or, like young students at schools across the country, from Mokena Elementary to Linden West Elementary School, deciding what special person in your life to invite to make gingerbread houses with you. :)

While there is no sound evidence that your Christmas gingerbread will cure you of cancer, it does have one very special benefit — one of special importance this time of year. That’s the ability to leave a child with a lifetime of cherished memories and to bring joy and pleasure to the hearts and tummies of children of all ages. The largest gingerbread village in the world was created last year to bring happiness to sick children at The Hospital for Sick Children, Canada’s research hospital affiliated with the University of Toronto. In the true spirit of Christmas, high school students had made it their class project. As the news explained:

...[T]he miniature town boasts more than 50 structures including a hardware store and even a hospital named after Sick Kids with individual rooms that light up. More than 1,000 kg of gingerbread was used and best of all, everything is 100 percent edible — except the lights, of course. With marshmallow roofs and candy cane picket fences, kids flocked to the treat-filled town....

The candy-covered gingerbread houses brought smiles and delight to the children and their families — and there is good evidence of that!

Merry Christmas!

To spread the joy of gingerbread houses, Loreta Anderson has created a website — Gingerbread Patterns — with everything you could possibly want to know about gingerbread and how to build fabulous gingerbread houses. It comes complete with photos of gingerbread houses around the world.

For added sugar and spice, two histories of Gingerbread Makers and Gingerbread Traditions include wonderful stories of gingerbread around the world. Recipes included.

© 2007 Sandy Szwarc

* Adjusted for age, age at menarche, age at menopause, parity, duration of oral contraceptives use, duration of postmenopausal hormone use, BMI, height, current smoking, quantity of smoking (cigarettes/d), duration of smoking years, saturated fat intake (energy-adjusted), trans-unsaturated fatty acid intake (energy-adjusted).

** Adjusted for: age, age at menarche, age at menopause, age at first childbirth, parity, duration of oral contraceptives use, duration of postmenopausal hormone use, BMI, height, current smoking, quantity of smoking (cigarettes/d), duration of smoking years, non-occupational physical activity, energy intake (kcal/day), transunsaturated fatty acid intake, carbohydrate intake (energy-adjusted, alcohol consumption.

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