Researchers have uncovered evidence that sugar has a direct effect on risk factors for heart disease, and is likely to impact on blood pressure, independent of weight gain.

Research Fellow with Otago's Department of Human Nutrition Dr Lisa Te Morenga, Professor Jim Mann and colleagues have conducted a review and meta-analysis of all international studies that compared the effects of higher versus lower added sugar consumption on blood pressure and lipids (blood fats or cholesterol) - both of which are important cardiovascular risk-factors.

They located dietary intervention trials published in English-speaking journals between 1965 and 2013, comparing diets where the only intended differences were the amount of sugars and non-sugar carbohydrates consumed by the participants, and which measured the effects of these diets on lipids and blood pressure.

They found 37 trials reporting effects on lipids and 12 reporting effects on blood pressure. The findings from the individual trials were then pooled to determine the overall effects from all the studies.

Dr Te Morenga says previous research showed that there did not appear to be any special metabolic effect of sugars making people more likely to gain weight on high-sugar diets compared with low sugar diets when the total amount of carbohydrates and energy remains the same.

The research has been published online in the American Journal of Clinical Nutrition.