Extramural papers of the month
By Nancy Lamontagne
- Rice consumption and arsenic exposure in pregnant women
- Consuming canned soup linked to higher BPA levels
- Dietary compounds could help protect kidney function
- Estrogen lessens effects of obesity and alcohol on breast cancer
Rice consumption and arsenic exposure in pregnant women
NIEHS grantees report that urinary arsenic concentrations were higher for pregnant women who had recently consumed rice than for those who had not. The findings highlight the need to monitor arsenic levels in food.
The researchers tested for arsenic in the urine of 229 pregnant women in New Hampshire, 73 of whom reported eating rice during the two days before urine collection. The arsenic concentration of the tap water in the women’s homes was also tested to identify any exposure from drinking water. The women who reported eating rice during the two days prior to urine collection had a median total urinary arsenic concentration of 5.27 micrograms per liter, which was significantly different from the 3.38 micrograms per liter median concentration for those who did not consume rice.
The researchers note the need for more research to determine any health impacts of this source of exposure. Any identified health risks will also need to be weighed against the nutritional benefits of eating rice.
Citation: Gilbert-Diamond D, Cottingham KL, Gruber JF, Punshon T, Sayarath V, Gandolfi AJ, Baker ER, Jackson BP, Folt CL, Karagas MR. 2011. Rice consumption contributes to arsenic exposure in US women. Proc Natl Acad Sci U S A 108(51): 20656-20660.
Consuming canned soup linked to higher BPA levels
Researchers funded by NIEHS found that a group of volunteers who consumed a serving of canned soup every day for five days had more than a 1,000 percent increase in urinary bisphenol A (BPA) concentrations than when the same individuals consumed fresh soup daily for five days. The endocrine disruptor BPA is used in the lining of metal food and beverage cans and has been shown to have adverse health effects.
The researchers recruited 75 volunteers and asked a group of them to consume a 12-ounce serving of vegetarian canned soup each day for five days, while the rest consumed 12 ounces of vegetarian fresh soup, prepared without canned ingredients, daily for five days. After a two-day break, the groups reversed their assignments.
The researchers detected BPA in 77 percent of the urine samples taken after fresh soup consumption and in all of the samples after canned soup consumption. Eating a serving of canned soup daily was associated with a 1,221 percent increase in BPA concentration compared to levels in urine collected after consumption of fresh soup. Even though the elevation in urinary BPA concentrations might be temporary, the researchers comment that their findings could be important, especially as more and improved alternatives to epoxy linings are developed.
Citation: Carwile JL, Ye X, Zhou X, Calafat AM, Michels KB. 2011. Canned soup consumption and urinary bisphenol A: a randomized crossover trial. JAMA 306(20):2218-2220.
Dietary compounds could help protect kidney function
NIEHS-funded researchers have shown that compounds found in vegetables and cinnamon helped reduce kidney damage, and preserve kidney function in a mice model of diabetes. Medicines used to protect kidney function in people with diabetes often cause toxicity, so better therapies are needed.
The researchers experimented with sulforaphane, which is found in vegetables such as broccoli and cauliflower, as well as cinnamic aldehyde, a flavor component of cinnamon. These compounds activate a transcription factor called NFE-2-related factor 2 (Nrf2), which regulates expression of various genes to neutralize free radicals and accelerate toxin removal.
They induced diabetes in Nrf2 deficient (-/-) mice, as well as those that expressed Nrf2 (+/+), and then administered sulforaphane or cinnamic aldehyde two weeks later. In the mice expressing Nrf2, both compounds improved kidney performance, minimized kidney damage, and significantly lessened diabetes-associated symptoms, such as high blood sugar, excessive thirst, and weight loss. Since only the mice expressing Nrf2 showed beneficial effects, these results indicate that the compounds activate the Nrf2 pathway.
The researchers conclude that the study lays the foundation for clinical evaluation and future development of new Nrf2 activators that could prevent the onset and progression of kidney problems that are associated with diabetes.
Citation: Zheng H, Whitman SA, Wu W, Wondrak GT, Wong PK, Fang D, Zhang DD. 2011. Therapeutic potential of Nrf2 activators in streptozotocin-induced diabetic nephropathy. Diabetes 60(11):3055-3066.
Estrogen lessens effects of obesity and alcohol on breast cancer
Obesity and alcohol consumption increase risk for developing breast cancer and fatty liver, a condition where fat accumulates in liver cells. A study performed by NIEHS grantees has shown that estrogen can protect against these adverse health effects.
The researchers used female mice that mimic post menopause to study the effect of alcohol consumption, obesity, and estrogen supplementation on breast cancer. Overweight and obese mice consumed either water or alcohol, were implanted with placebo or estrogen pellets, and then injected with Met-1 breast cancer cells. The mice that consumed alcohol were more insulin sensitive and developed larger tumors than those that consumed water, and the obese mice developed tumors that were slightly larger than those in the overweight mice. However, all the mice receiving estrogen experienced loss of body fat, increased insulin sensitivity, suppressed tumor growth, reduced growth factors, and lessened retention of fat in the liver cells.
Citation: Hong J, Holcomb VB, Kushiro K, Núñez NP. 2011. Estrogen inhibits the effects of obesity and alcohol on mammary tumors and fatty liver. Int J Oncol 39(6):1443-1453.
(Nancy D. Lamontagne is a science writer with MDB, Inc., a contractor for the NIEHS Division of Extramural Research and Training, Superfund Research Program, and Worker Education and Training Program.)