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Sugar has a direct effect on risk factors for heart disease, including rising blood pressure, Kiwi researchers have found.
Nutritionists at the University of Otago reviewed all international studies comparing the effects of higher versus lower added sugar consumption on blood pressure and lipids (blood fats or cholesterol), which are important cardiovascular risk factors.
"Our analysis confirmed that sugars contribute to cardiovascular risk, independent of the effect of sugars on body weight," Dr Lisa Te Morenga, research fellow at the university's Department of Human Nutrition, said.
"Although the effects of sugars on blood pressure and lipids are relatively modest, our findings support public health recommendations to reduce added sugar in our diets as one of the measures which might be expected to reduce the global burden of cardiovascular diseases."
Dr Te Morenga and Professor Jim Mann studied 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.
Research showed that sugars did not make 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.
"However our latest study did find significant effects of sugars on lipids and blood pressure among these types of energy-controlled studies. This suggests that our bodies handle sugar differently to other types of carbohydrates," Dr Te Morenga said.
"In subgroup analyses we showed that by excluding the trials funded by the food/sugar industry, we found larger effects of sugar on lipids and blood pressure."
The release of their findings in the American Journal of Clinical Nutrition online is timely, she said, as national and international organisations consider recommendations on safe dietary sugar intakes.
"Our work provides further evidence to support these recommendations which have been disputed by the food industry," she said.
"While there is still a need for further longer term well-powered studies looking at the effects of sugars on various health outcomes, it is becoming increasingly difficult for the food industry to continue to claim that liberal sugar consumption is risk free."
- Patrice Dougan of APNZ