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Body weight, diet may be risk factors for non-Hodgkin lymphoma

December 17th, 2011 / tags:, , , , / categories: Uncategorized /

ScienceDaily (Oct. 24, 2011) — Body weight in young adulthood and diet appeared to be associated with the risk for non-Hodgkin lymphoma, according to results presented at the 10th AACR International Conference on Frontiers in Cancer Prevention Research, held Oct. 22-25, 2011.

“The causes of non-Hodgkin lymphoma (NHL) are poorly understood, and unfortunately, we don’t know very much about specific ways to prevent or lower the risk for this disease,” said Kimberly Bertrand, Sc.D., research fellow in the department of epidemiology at the Harvard School of Public Health.

In previous analyses of the Nurses’ Health Study at 14 years of follow-up, lead researcher Shumin Zhang, M.D., Sc.D., and colleagues reported positive associations with NHL for trans fat intake and inverse associations for vegetable intake. To expand those findings, Bertrand and colleagues evaluated the association of obesity, specific types of dietary fats, and fruits and vegetables with risk for NHL.

Researchers analyzed questionnaire responses from 47,541 men followed for 22 years in the Health Professionals’ Follow-Up Study and 91,227 women followed for 28 years in the Nurses’ Health Study. Among the women, researchers confirmed 966 incident diagnoses of NHL through 2008, and among the men, they confirmed 566 cases through 2006.

“In analyses that controlled for age, race and other factors, we found that obesity in young adulthood (ages 18 to 21 years) was associated with risk for NHL later in life,” Bertrand said. “Men who were obese (body mass index [BMI] equal to or greater than 30) [in young adulthood] had a 64 percent higher risk for NHL compared with men who were lean, while obese women had a 19 percent higher risk.”

Current BMI was also associated with risk for NHL in men but not in women. Although total and specific dietary fats were not associated with NHL risk, findings also suggested that women who consumed the highest amounts of trans fat in their diets had a nonstatistically significant increased risk for NHL overall. “We observed that women who consumed at least four servings of vegetables per day, compared with those who consumed fewer than two servings per day, had a 16 percent lower risk for developing NHL,” Bertrand said.

“The results from this study, if confirmed in other studies, suggest that body weight and dietary choices may be potentially modifiable risk factors for NHL,” she said. Bertrand and colleagues also plan to investigate associations of obesity and dietary factors with common subtypes of NHL, to evaluate biomarkers of fatty acids related to NHL risk to obtain more information on the possible biological mechanism for these associations, and to investigate other dietary factors including red meat consumption and antioxidants.

The study was supported by the American Cancer Society with funds to senior researcher, Brenda Birmann, M.Sc., Sc.D. (RSG-11-020-01-CNE), and by the National Institutes of Health (CA055075 and CA87969). Bertrand was supported by a training grant from the National Cancer Institute (R25 CA098566).

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The above story is reprinted from materials provided by American Association for Cancer Research.

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Article source: http://www.sciencedaily.com/releases/2011/10/111024084712.htm

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Childhood diet lower in fat and higher in fiber may lower risk for chronic disease in adulthood

December 17th, 2011 / tags:, , , , / categories: Uncategorized /

ScienceDaily (Oct. 27, 2011) — A recent study has found that a childhood behavioral intervention to lower dietary intake of total fat and saturated fat and increase consumption of foods that are good sources of dietary fiber resulted in significantly lower fasting plasma glucose levels and lower systolic blood pressure when study participants were re-evaluated in young adulthood.

The study was accepted for publication in The Endocrine Society’s Journal of Clinical Endocrinology and Metabolism (JCEM).

A Western dietary pattern high in total fat and saturated fatty acids and refined grains is associated with an increased risk of the metabolic syndrome, a cluster of metabolic abnormalities that include abdominal obesity, low levels of high-density lipoprotein cholesterol (sometimes considered “good cholesterol”), higher levels of triglycerides and blood glucose, and elevated blood pressure. This study evaluated the long-term effects of a dietary intervention to reduce fat and increase fiber intake during childhood on components of the metabolic syndrome in young adult women.

“This research is important because it suggests that modest reductions in total fat and saturated fat intake and increased consumption of dietary fiber during childhood and adolescence may have beneficial effects later in life by decreasing risk of chronic diseases such as diabetes and heart disease,” said Joanne Dorgan, PhD, of Fox Chase Cancer Center in Philadelphia, PA and lead author of the study.

In this study, researchers evaluated 230 women between the ages of 25 and 29 years, who nine years before the current study participated in the Dietary Intervention Study in Children (DISC). DISC was a randomized controlled clinical trial of a reduced-fat dietary intervention that strived to limit fat intake to 28 percent of daily caloric intake and increase dietary fiber intake by encouraging consumption of fruits, vegetables and whole grains. The current study was conducted among females who had participated in the DISC trial to determine the longer-term effects of the DISC intervention.

Researchers measured body composition of study participants using whole body dual-energy x-ray absorptiometry (DXA) scans. Blood pressure was measured using automatic blood pressure monitors and blood samples were analyzed to assess levels of plasma glucose, cholesterol and triglycerides.

“Few participants in our follow-up study met the criteria for metabolic syndrome, however the intervention group had statistically significant lower mean systolic blood pressure and fasting plasma glucose levels compared to the control group,” said Dorgan. “Significant differences at the follow-up visit, but not earlier, suggest that adolescent diet may have long-term effects on age-related changes in blood pressure and glycemic control that begin to become apparent in young adulthood. Longer follow-up studies of DISC participants are needed to determine if the differences found in this study persist or widen with increasing age.”

Other researchers working on the study include: Lea Liu of Clinical Trials Surveys Corporation in Owings Mills, MD; Bruce Barton of the University of Massachusetts in Shrewsbury; Snehal Deshmukh of Fox Chase Cancer Center; Linda Snetselaar of the University of Iowa in Iowa City; Linda Van Horn of Northwestern University in Chicago, IL; Victor Stevens of Kaiser Permanente Center for Health Research in Portland, OR; Alan Robson of Children’s Hospital in New Orleans, LA; Norman Lasser of the New Jersey Medical School in Newark; John Himes of the University of Minnesota in Minneapolis; John Shepherd of the University of California San Francisco; Ray Pourfarzib of LipoScience Inc. in Raleigh, NC; Kelley Pettee Gabriel of the University of Texas in Austin; Andrea Kriska of the University of Pittsburgh in PA; and Peter Kwiterovich, Jr. of Johns Hopkins Hospital in Baltimore, MD.

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The above story is reprinted from materials provided by The Endocrine Society.

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Journal Reference:

  1. J. F. Dorgan, L. Liu, B. A. Barton, S. Deshmukh, L. G. Snetselaar, L. Van Horn, V. J. Stevens, A. M. Robson, N. L. Lasser, J. H. Himes, J. A. Shepherd, R. Pourfarzib, K. Pettee Gabriel, A. Kriska, P. O. Kwiterovich. Adolescent Diet and Metabolic Syndrome in Young Women: Results of the Dietary Intervention Study in Children (DISC) Follow-Up Study. Journal of Clinical Endocrinology Metabolism, 2011; DOI: 10.1210/jc.2010-2726

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Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Article source: http://www.sciencedaily.com/releases/2011/10/111027083045.htm

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Immunity against the cold

December 15th, 2011 / tags:, , , , , / categories: Uncategorized /

ScienceDaily (Dec. 13, 2011) — Throughout the interior spaces of humans and other warm-blooded creatures is a special type of tissue known as brown fat, which may hold the secret to diets and weight-loss programs of the future.

Unlike ordinary “white” fat, in which the body stores excess calories, brown fat can burn calories to heat up the body. It’s one of the things that helps keep wild critters warm on cold nights.

Investigating how brown fat works in mice, a team of researchers at the University of California, San Francisco (UCSF) has uncovered what may be a holdover from our evolutionary past: in response to cold, tiny immune cells known as macrophages can switch on the brown fat, inducing it to burn energy to make heat.

Prior to this research, published last month in the journal Nature, scientists had assumed that brown fat metabolism was completely controlled by the brain. But the UCSF research suggests that the immune system plays a backup role in this process — a legacy, perhaps, of some ancient ancestral creature whose metabolic and immune systems were much more intertwined.

“This is a very important secondary system that the body uses to provide a backup for the thermal stress response,” said Ajay Chawla, MD, PhD, an associate professor at UCSF’s Cardiovascular Research Institute who led the research. “It raises the possibility that we can perhaps modulate this program and enhance it in humans to rev up metabolism.”

Immune Cells Found Inside Brown Fat

The modern human immune system relies on these macrophages to gobble up bacteria, helping protect us against infection. Macrophages were never known to play a role in metabolism, but the evidence Chawla and his colleagues gathered suggests otherwise.

Using brown fat to burn calories and produce heat is one of the ways that mammals maintain thermoregulation — an essential adaptation that defines warm blooded creature and enables them to thrive in the face of challenging environmental extremes. Not all animals share this ability.

Many animals, like lizards, are “cold blooded” or exothermic. They maintain their body temperature through completely external means, sunbathing at certain times of the day and huddling in warm, protective places at night. This naturally limits their range and explains why lizards, so abundant in tropical climates, are far rarer in cold climates.

Mammals, on the other hand, are “warm-blooded” or endothermic. They produce heat internally by a variety of means: shivering, sweating, regulating the size of their blood vessels and burning off excess calories in brown fat.

Scientists have known for years that brown fat burns calories in response to signals from the brain. These signals cause break down of molecules known as triglycerides in white fat, which are then released into the bloodstream as fatty acids. These circulating fatty acids are taken up by brown fat and burned to generate heat. Brown fat is full of blood vessels, and the heat warms the blood, which in turn circulates and warms the body.

The brain controls this process by monitoring the body’s temperature and, in face of extreme cold, releasing a hormone called norepinephrine, which kick-starts the brown fat.

The work of the UCSF team showed that macrophage cells within the brown fat can also do this directly. Macrophages residing in brown and white fat produce an enzyme that makes norepinephrine when mice are exposed to the cold. This leads to the production, the breakdown and mobilization of stored fat, which is then burned in brown fat to produce heat.

What these results suggest, Chawla said, is that immune cells help facilitate the function of brown fat.

Mammals today have evolved to have separate systems for immunity and metabolism. But flies, for instance, have combined the equivalent functions of the human liver, fat and immune system into one organ: a tissue referred to as its fat body. Mammalian macrophages may have some functions related to this shared origin.

The article, “Alternatively activated macrophages produce catecholamines to sustain adaptive thermogenesis” by Khoa D. Nguyen, Yifu Qiu, Xiaojin Cui, Y. P. Sharon Goh, Julia Mwangi, Tovo David, Lata Mukundan, Frank Brombacher, Richard M. Locksley and Ajay Chawla appeared in the Nov. 20 issue of Nature.

In addition to UCSF, the authors of this study are affiliated with Stanford University and the University of Cape Town, South Africa.

This work was funded by grants from the National Institutes of Health and the Larry L. Hillblom Foundation; by an National Institutes of Health Director’s Pioneer Award; and by Stanford Graduate and A-STAR Fellowships.

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The above story is reprinted from materials provided by University of California – San Francisco. The original article was written by Jason Bardi.

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Journal Reference:

  1. Khoa D. Nguyen, Yifu Qiu, Xiaojin Cui, Y. P. Sharon Goh, Julia Mwangi, Tovo David, Lata Mukundan, Frank Brombacher, Richard M. Locksley, Ajay Chawla. Alternatively activated macrophages produce catecholamines to sustain adaptive thermogenesis. Nature, 2011; 480 (7375): 104 DOI: 10.1038/nature10653

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Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Article source: http://www.sciencedaily.com/releases/2011/12/111213092140.htm

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