Sunday, October 03, 2010

Think Saturated Fat Contributes to Heart Disease? Think Again…

Leading Scientists Re-Examine the Role of Saturated Fat in the Diet

For the past three decades, saturated fat has been considered a major culprit of cardiovascular disease (CVD) and as a result dietary advice persists in recommending reduced consumption of this macronutrient. However, new evidence shows that saturated fat intake has only a very limited impact on CVD risk -- causing many to rethink the “saturated fat is bad” paradigm.

A series of research articles published in the October issue of Lipids[1] provides a snapshot of recent advances in saturated fat and health research, based on science presented at the 100th American Oil Chemists’ Society (AOCS) annual meeting in Orlando, Florida (May 2009). During a symposium entitled “Saturated Fats and Health: Facts and Feelings,” world-renowned scientists specializing in fat research analyzed the evidence between saturated fat intake and health, and overall agreed upon the need to reduce over-simplification when it came to saturated fat dietary advice.

“The relationship between dietary intake of fats and health is intricate, and variations in factors such as human genetics, life stage and lifestyles can lead to different responses to saturated fat intake,” said J. Bruce German, PhD, professor and chemist in the Department of Food Science and Technology, University of California at Davis. “Although diets inordinately high in fat and saturated fat are associated with increased cardiovascular disease risk in some individuals, assuming that saturated fat at any intake level is harmful is an over-simplification and not supported by scientific evidence.”

Professor Philippe Legrand of Agrocampus-INRA in France confirmed this by discussing various roles that different saturated fatty acids play in the body. His main conclusion was that saturated fats can no longer be considered a single group in terms of structure, metabolism and cellular function, and recommendations that group them together with regard to health effects need to be updated.

Effect of Saturated Fat Replacement on CVD Risk

Results from a research review conducted by Dariush Mozaffarian, MD, MPH, Department of Epidemiology and Nutrition at Harvard University School of Public Health, found that the effects of saturated fat intake on CVD risk depend upon simultaneous changes in other nutrients. For example, replacing saturated fat with mono-unsaturated fat yielded uncertain effects on CVD risk, while replacing saturated fat with carbohydrates was found to be ineffective and even harmful especially when refined carbohydrates such as starches or sugars were used in place of fat[2]. Replacing saturated fat with polyunsaturated fat gave a small reduction in CVD risk, but even with optimal replacement the magnitude of the benefit was very small. According to Mozaffarian it would be far better to focus on dietary factors giving much larger benefits for CVD health, such as increasing intake of seafood/omega-3 fatty acids, whole grains, fruits and vegetables, and decreasing intake of trans fats and sodium.

‘’Carbohydrate intake has been intimately linked to metabolic syndrome, which is a combination of risk factors that can increase CVD risk,’’ said Jeff Volek, PhD, RD, Department of Kinesiology, University of Connecticut. His research showed that very low carbohydrate diets can favorably impact a broad spectrum of metabolic syndrome and cardiovascular risk factors, even in the presence of high saturated fat intake and in the absence of weight loss.

Kiran Musunuru, MD, PhD, MPH. Cardiovascular Research Center and Center for Human Genetic Research, Massachusetts General Hospital, focused on the role of carbohydrates and fats on atherogenic dyslipidemia – a new marker for CVD risk often seen in patients with obesity, metabolic syndrome, insulin resistance and type 2 diabetes. He showed that low-carbohydrate diets appear to have beneficial lipoprotein effects in individuals with atherogenic dyslipidemia, compared to high-carbohydrate diets, whereas the content of saturated fat in the diet has no significant effect.

Full-Fat Dairy: An Unnecessary Target?

As long as saturated fat targets remain firmly rooted in dietary advice, nutrient-rich foods that contribute saturated fat to the diet, like full-fat dairy products, will continue to be unduly criticized regardless of their health benefits.

A recent meta-analysis of epidemiological and intervention studies of milk fat conducted by Peter Elwood, DSc, MD, FRCP, FFPHM, DUniv, Hon DSc, Honorary Professor at the School of Medicine, Cardiff University, found that milk and dairy consumption actually was associated with a decrease in CVD risk[3].

“It is clear that we have barely scratched the surface in our understanding about the biological effects of saturated fatty acids,” said Cindy Schweitzer, PhD, Technical Director, Global Dairy Platform. “Scientific meetings where researchers from different disciplines within the field of nutrition share information are extremely important to identify both the gaps in our knowledge and the studies that are needed to answer the important questions about diet and health.”

All of these recent research advances add to the growing body of science re-assessing the role of saturated fat in the diet. Whether it’s nutrient replacement or better understanding the role certain foods can play in CVD risk, saturated fat is definitely not be as bad as once thought.

To view the relevant papers from Lipids visit here


Cancer genes "turned down"

A new cancer vaccine concept developed by researchers at The University of Queensland's Diamantina Institute has been licensed to US-based developer of RNAi (ribonucleic acid interference) therapeutics, Alnylam Pharmaceuticals, Inc., through UniQuest, UQ's main research commercialisation company.

The intellectual property licensed exclusively to Alnylam relates to research from Associate Professor Nigel McMillan's molecular virology group, which was described in a paper published in the Proceedings of the National Academy of Sciences. The work investigated the use of RNAi to induce an effective immune response against tumours.

One of the most exciting aspects of this rapidly advancing frontier in biomedical research, according to Associate Professor McMillan, is the potential for treating diseases and helping patients in a fundamentally new way. “It's one of those holy grail areas of cancer research – finding a way for the immune system to ‘see' cancer cells, which are very good at hiding away," Associate Professor McMillan said. "Even current therapies such as chemotherapy and radiation treatment ultimately need the immune system to ‘clean up' cancer cells.”

“RNA Interference is like the volume control on a radio – a way to turn down the expression (or volume) of single genes. "Cancer is often caused by certain genes being over-expressed (or turned up far too loud) and now that the sequencing of the human genome is complete we have begun to understand which genes need turning down.

“A surprising finding from our RNAi work is that not only can we turn down genes, but we can also alert the immune system to the presence of a cancer cell. "This means we can treat a few cancer cells and the immune system, now aware of the cancer, can attack and remove the rest of the untreated tumours.”

UQ's Diamantina Institute put Queensland in the spotlight in 2006 when Gardasil was launched globally - the cervical cancer vaccine developed from the research of Institute Director Professor Ian Frazer and the late Dr Jian Zhou.

Associate Professor McMillan's RNAi research has used cervical cancer as a model system to test RNAi therapy. “In cervical cancer where genes from the human papilloma virus are driving the cancer, we have shown that turning off these genes by RNAi causes these cancer cells to stop growing and die," he said.

UniQuest also commercialised the intellectual property relating to Professor Frazer and Dr Zhou's discovery.

“This licensing agreement opens up new opportunities for RNAi-based products to be developed into vaccines for cancers and infectious diseases,” UniQuest Managing Director, David Henderson said.

“Partnering with an international company such as Alnylam promotes collaboration and makes it possible for the Australian research community to contribute directly to global efforts in the fight against a range of terminal and chronic human illnesses,” Mr Henderson said.

Dr Stuart Pollard, Vice President, Scientific and Business Strategy at Alnylam, said the company was pleased to have secured key vaccine-related intellectual property, which describe opportunities for the advancement of novel RNAi-based vaccines in many human diseases. “While our primary focus remains on the development of RNAi therapeutics, Alnylam's strategy is to also explore the full breadth of RNAi applications in medicine," Dr Pollard said.

The role of RNA molecules has been under the microscope since nucleic acids were first discovered in 1868; however, RNAi and the implications gene silencing may have for drug discovery and development are widely acknowledged to represent one of the most significant biology breakthroughs already this century.


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