1 June 2009

News Briefs

5 tips to reduce your risk of diabetes
When researchers checked out the lifestyle habits of some 4,900 adults, aged 65 or older and without diabetes over a 10-year period, they found that the factors associated with low risk for diabetes were:


  • physical activity
  • a healthy diet
  • no smoking
  • moderate alcohol use
  • not being overweight
The researchers showed that 80% of new cases of diabetes are attributable to these risk factors, a number that increases when obesity is included. 'Our findings suggest that, even later in life, the great majority of cases of diabetes are related to lifestyle factors,' write Dariush Mozaffarian (Brigham and Women's Hospital, Boston, MA) and colleagues in the April 27, 2009 issue of the Archives of Internal Medicine. 'Our results support the need for emphasising healthy and achievable physical activity and dietary goals among older adults, including:
  • moderate leisure-time activity and walking pace,
  • higher intake of dietary fiber and polyunsaturated fat, and
  • lower intake of trans fat and easily digestible [high GI] carbohydrates.'
More bang with low GI foods for your exercise buck
‘If you are trying to shed fat, you may consider eating low GI foods before you exercise,’ suggests Dr Emma Stevenson after a recent University of Nottingham study published in the Journal of Nutrition found that a low GI breakfast before exercising could help with weight loss because it increases fat oxidation both at rest and during subsequent exercise.

Dr Emma Stevenson

In the study, eight healthy, sedentary but not overweight women ate either a high GI breakfast (cornflakes and milk, white bread and jam and a carbonated glucose drink) or a low GI one (natural muesli and milk, tinned peaches and yoghurt and apple juice) in test sessions held several days apart (each breakfast contained the same number of calories and same proportion of those calories from carbs, fat and protein). Three hours later they did a 60-minute walk on a treadmill, which was set to make them work but not to the point of exhaustion, before having lunch.

Blood glucose was higher – as expected – after the high GI breakfast than the low GI one, and had returned to normal levels by the time the women started to exercise. But plasma free fatty acids (FFA) – which indicate the amount of fat being used as an energy source – began to rise two hours after the low GI breakfast was consumed. Exercise led to a rapid increase in FFAs in both groups – but concentrations were higher in the low GI group. After lunch the concentration of FFAs was the same in both groups, but overall fat oxidation was higher in the low GI group than the high GI group. ‘A low GI breakfast also had an impact on appetite, with the women feeling fuller for longer after they’d eaten these types of foods,’ said Dr Stevenson.


How high glucose might damage blood vessels
Diabetes increases the risk of cardiovascular disease such as heart disease and stroke, even when blood glucose levels are under control. In fact, about 75% of people with diabetes die from some form of heart or blood vessel disease, according to the American Heart Association. Medical College of Georgia researchers now suspect increased modification of proteins by a glucose-derived molecule is a player in vascular problems associated with hypertension, stroke and obesity as well. The found that a decreased ability of blood vessels to relax resulted from increased activity of a natural mechanism for altering protein form and function, according to Dr Rita C.Tostes, physiologist in the MCG School of Medicine.

One aftermath of high glucose levels is low levels of the powerful vasodilator nitric oxide in blood vessels, a shortfall that increases the risk of high blood pressure and eventual narrowing of the vessels, researchers reported at the American Society of Hypertension 24th Annual Scientific Program in San Francisco during a joint session with the Council for High Blood Pressure.

Most of the glucose in the body is carried by the blood stream to the body’s cells where it provides fuel for energy. However about 5% of all glucose is converted to O-GlcNAc, one of the sugar types that can modify proteins.


Inside the blood vessel walls of healthy mice, MCG researchers found increased activity by O-GlcNAc competes with another mechanism for modifying proteins called phosphorylation. In blood vessels, phorphorylation modifies the enzyme that produces nitric oxide, called nitric oxide synthase, so that it makes more of the blood vessel dilator. But add more O-GlcNAc to the mix and it seems to beat phosphorylation to the punch so there is the opposite result. The longer O-GlcNAc levels were high, the worse the resulting problem, says Victor Lima, a graduate student at the University of Sao Paulo working with Dr Tostes.

An animal model of hypertension seemed to confirm the finding that the more O-GlcNAc, the more blood vessels contract because these animals had higher O-GlcNAc levels. 'Now we are trying to see why this is happening and what comes first. Is increased blood pressure leading to changed O-GlcNAc or are augmented levels of O-GlcNAc contributing to the change we see in the vasculature of hypertensives?' Dr Tostes says. 'If we know how this changes vascular function, we can understand some of the dysfunction that we see in diabetes.'

To make sure they were targeting the O-GlcNAc sugar and not dealing with other effects of glucose on blood vessels, the researchers blocked the enzyme OGA, an enzyme that normally removes O-GlcNAc from proteins so they can revert to their normal state.

If the findings continue to hold true, drugs similar to those they use in the lab to inhibit OGA or OGT, the enzyme that adds O-GlcNAc to the protein, could one day help reduce the significant cardiovascular risk associated with diabetes, Mr Lima says.

International Diabetes Federation streamlines website


‘We want to serve the needs of people with diabetes, people interested in learning more about diabetes, of governments and researchers looking for evidentiary data about the diabetes epidemic, and of diabetes and health associations looking for global material on diabetes care, prevention and education,’ said Mario Fetz, IDF Director of External Relations. www.idf.org is available in three languages and is integrated with Facebook and Twitter.


Anonymous said...

I can understand the possible appetite suppression and increased fat oxidation with a low-GI meal before exercise, but increased fat oxidation at any particular point in time will not make any difference to weight loss over time. This is not, presumably, metabolic up-regulation, only preferential fuel substrate use.

It's still calories in, calories out.