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Of carbs and cancer: What scientists look at in a cell

What can carbs tell scientists about what's going on inside a cell? Researchers identify 'carbohydrates in a coal mine' for cancer detection. Researchers at New York University and the University of Texas at Austin have discovered that carbohydrates serve as identifiers for cancer cells. Their findings, which appear in the journal Proceedings of the National Academy of Sciences show how these molecules may serve as signals for cancer and explain what's going on inside these cells, pointing to new ways in which sugars function as a looking glass into the workings of their underlying structures.

"Carbohydrates can tell us a lot about what's going on inside of a cell, so they are potentially good markers for disease," says Lara Mahal, an associate professor in NYU's Department of Chemistry and the study's corresponding author, according to the March 3, 2014 news release, Researchers identify 'carbohydrates in a coal mine' for cancer detection. "Our study reveals how cancer cells produce certain 'carbohydrate signatures' that we can now identify."

Carbohydrates, or glycans, are complex cell-surface molecules that control multiple aspects of cell biology, including cancer metastasis

Less understood is the link between categories of cells and corresponding carbohydrate structures. That is, what do certain carbohydrates on a cell's surfaces tell us about its characteristics and inner workings or, more succinctly, how do you read a code backwards?

Specific miRNAs—such as miR-200—play a role in controlling tumor growth. Using microarray technology developed by NYU's Mahal, the team examined cancer cells in an effort to see how they generated a carbohydrate signature. Specifically, they mapped how miRNA controls carbohydrate signatures.

In the PNAS study, the researchers examined the role of microRNA, non-coding RNA that are regulators of the genome.

In their analysis, the researchers could see that miRNA molecules serve as major regulators of the cell's surface-level carbohydrates—a discovery that showed, for the first time, that miRNA play a significant regulatory role in this part of the cell, also known as the glycome. Moreover, they could see which regulatory process was linked to specific carbohydrates.

"Carbohydrates aren't just telling you the type of cell they came from, but also by which process they were created," explains Mahal in the news release. "Our results showed that there are regulatory networks of miRNAs and that they are associated with specific carbohydrate codes." A grant from the National Institutes of Health (7 DP2 OD004711-02) supported the study.

Whole grains and older adults

Older adults may reduce risk of metabolic syndrome by eating more whole grains, says a study. Research from the Friedman School of Nutrition Science and Policy at Tufts University, according to a 2006 study, "Whole-grain intake is inversely associated with the metabolic syndrome and mortality in older adults," published in the January 2006 issue of the American Journal of Clinical Nutrition. Authors of the study are Sahyoun NR , Jacques PF, Zhang XL, Juan and W, McKeown NM.

With the recent revision of the Food Guide Pyramid, the Dietary Guidelines for Americans have for the first time provided the public with a quantitative recommendation for whole-grain intake. In a study published in the January issue of American Journal of Clinical Nutrition, researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University (HNRCA) found that consuming a diet rich in whole-grain foods may lower an elderly person's risk for cardiovascular disease and reduce the onset of metabolic syndrome. Metabolic syndrome, which is a collection of risk factors, puts people at an increased risk of cardiovascular disease and type 2 diabetes.

The relationship between eating whole grains and heart and artery disease risk factors or reduced incidence of metabolic syndrome

The study, a collaborative effort that included Paul Jacques, DSc, director of the Nutritional Epidemiology Program at the HNRCA, Nicola McKeown, PhD, scientist in the same program, and others, examined the relationship between whole-grain intake and cardiovascular disease risk factors, metabolic syndrome, and the incidence of death due to cardiovascular disease in the elderly.

"Previous studies have found a link between whole-grain intake and reduced risk of metabolic syndrome in middle-aged populations. What's unique about our study," says McKeown, according to a February 6, 2006 news release, Older adults may reduce risk of metabolic syndrome by eating more whole grains, "is that we went back to data that was collected 20 years ago, using diet records that captured food intake, and found that whole-grain foods had a subsequent benefit in the elderly."

The ability of researchers to differentiate whole grains from refined grains more accurately through the use of diet records is a major advantage when assessing dietary intake. "In past studies," states McKeown, in the news release, "fixed food categories have made it difficult to accurately separate whole and refined grains for some food items – such as breads."

According to Jacques, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts, "consuming a high whole-grain diet is likely to have positive metabolic effects in elderly individuals, who are prone to greater insulin resistance and impaired glucose tolerance."

McKeown and Jacques found that, indeed, as whole-grain intake increased, fasting blood sugar levels were lower in these subjects. Refined grain intake, on the other hand, was associated with higher fasting blood sugar levels.

Elevated fasting blood sugar levels can indicate impaired glucose tolerance and the presence of diabetes

In addition, people who consumed high amounts of refined grains had twice the risk of having metabolic syndrome than those people who consumed the fewest servings of refined grains. But how many doctors also look at too-high insulin levels in the blood after eating instead of only looking at fasting glucose levels?

"It is important to note," cautions McKeown, according to the news release, "that the subjects in the study were not a representative sample of the elderly, so we do not know the implications of applying these results to other populations. Based on the research, whole-grain intake is one modifiable dietary risk factor that may lead to substantial health benefits at the population level, even among an older population. Older adults should be encouraged to increase their daily intake of whole grain foods to three or more servings a day by substituting whole grains for refined grains."

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