Reacting to findings from researchers from The Johns Hopkins University School of Medicine, Dr James Rippe from the Rippe Lifestyle Institute (RLI) told FoodNavigator: “While this may be interesting science, it must be approached with extreme caution when attempting to extrapolate this type of information to human nutrition, behavior or health.”
The John Hopkins researchers, led by Dr M. Daniel Lane, reported their findings in the journal Biochemical and Biophysical Research Communications. According to recent research, the way glucose and fructose are metabolised in the brain produces inverse effects on food intake.
“We feel that these findings may have particular relevance to the massive increase in the use of high fructose sweeteners (both high fructose corn syrup and table sugar) in virtually all sweetened foods, most notably soft drinks,” said Dr Lane.
To read our full coverage of the John Hopkins review, please click here.
However, Dr Rippe said caution is needed when results from ‘basic biochemistry’ are extrapolated to humans. “Pure fructose is consumed in extremely limited quantities in the human diet…certainly less than 1 per cent of calories, probably less than 1/10th of 1 per cent of calories,” he said.
“It is extremely important to make a clear distinction between pure fructose and compounds which contain fructose such as sucrose (table sugar), High Fructose Corn Syrup and honey, as well as various fruit juices.”
Dr Rippe added that, in the human diet, fructose is almost always consumed in the presence of glucose. He noted that sucrose is composed of 50 per cent glucose and 50 per cent fructose, while HFCS is either 55 per cent fructose, 43 per cent glucose and 2 per cent other carbohydrates (HFCS-55), or 42 per cent fructose and 58 per cent glucose (HFCS-42).
“The presence of glucose in combination with fructose clearly alters absorption and metabolism of fructose, although the specifics of exactly what occurs remain in debate and under investigation,” he said.
Complex situations
Dr Rippe, who names Pepsico and Tropicana amongst his partners, added that human appetite and eating behaviours are very complex. “To make the leap from biochemical signaling in the brain to eating behaviour is very dangerous and highly speculative,” he said.
“In our research laboratory we showed no difference in either appetite or calories consumed during ad libitum meals following consumption of either High Fructose Corn Syrup or sucrose.”
Caloric intakes have increased by 24 per cent over the last three decades, said Dr Rippe, with fat intakes increasing by 5 per cent, and calories from sweeteners decreasing by 1 per cent.
“To speculate, as Lane and Cha do, that the biochemical pathways they describe can lead to over consumption of food and obesity is highly speculative and probably incorrect,” he said.
Dr Rippe made reference to the American Medical Association’s 2008 conclusions that: “High Fructose Corn Syrup does not contribute to obesity more than other calorie sweeteners."
“The causes of obesity are well known: increased caloric consumption and decreased physical activity. To blame fructose consumption for obesity is not founded on modern scientific evidence and consensus,” said Dr Rippe.