Free sugars overconsumption is associated with an increased prevalence of risk factors for metabolic diseases such as the alteration of the blood lipid levels. Natural fruit juices have a free sugar composition quite similar to that of sugar-sweetened beverages. Thus, could fruit juice consumption lead to the same adverse effects on health as sweetened beverages? We attempted to answer this question by reviewing the available evidence on the health effects of both sugar-sweetened beverages and natural fruit juices. We determined that, despite the similarity of fruits juices to sugar-sweetened beverages in terms of free sugars content, it remains unclear whether they lead to the same metabolic consequences if consumed in equal dose. Important discrepancies between studies, such as type of fruit juice, dose, duration, study design, and measured outcomes, make it impossible to provide evidence-based public recommendations as to whether the consumption of fruit juices alters the blood lipid profile. More randomized controlled trials comparing the metabolic effects of fruit juice and sugar-sweetened beverage consumption are needed to shape accurate public health guidelines on the variety and quantity of free sugars in our diet that would help to prevent the development of obesity and related health problems.

OBJECTIVE—To assess the effect of age on glucose metabolism by examining 1) glucose metabolism in young and middle-aged subjects when total or regional adiposity is taken into account and 2) in vitro glucose transport in adipose tissue explants from young and middle-aged women paired for total and abdominal adiposity. RESEARCH DESIGN AND METHODS—Study 1: body composition, subcutaneous abdominal and visceral adipose tissue areas, and fasting and oral glucose–stimulated glucose and insulin were measured in 84 young and 81 middle-aged men and in 110 young and 91 middle-aged women. Study 2: glucose uptake in subcutaneous abdominal and visceral adipose tissue explants were measured in eight young and eight middle-aged women. RESULTS—Study 1: young and middle-aged men showed similar subcutaneous abdominal tissue area, whereas fat mass and visceral adipose tissue were greater in middle-aged than in young men (P < 0.01). Fat mass and subcutaneous and visceral adipose tissue areas were greater in middle-aged as compared with young women (P < 0.01). Fasting plasma glucose and the glucose response to an oral glucose tolerance test were significantly higher in middle-aged than in young men and women (P < 0.001). Statistical control for visceral adipose tissue area eliminated the difference seen in glucose response in men and women. Study 2: glucose transport in subcutaneous and omental adipose tissue did not differ between young and middle-aged women. CONCLUSIONS—1) Visceral obesity, more than age per se, correlates with glucose intolerance in middle-aged subjects; 2) aging does not influence in vitro adipose tissue glucose uptake.

Background: Adipose tissue regulates postprandial lipid metabolism by storing dietary fat through lipoprotein lipase-mediated hydrolysis of exogenous triglycerides, and by inhibiting delivery of endogenous non-esterified fatty acid to nonadipose tissues. Animal studies show that acute hypoxia, a model of obstructive sleep apnea, reduces adipose tissue lipoprotein lipase activity and increases non-esterified fatty acid release, adversely affecting postprandial lipemia. These observations remain to be tested in humans. Methods: We used differentiated human preadipocytes exposed to acute hypoxia as well as adipose tissue biopsies obtained from 10 healthy men exposed for 6 h to either normoxia or intermittent hypoxia following an isocaloric high-fat meal. Results: In differentiated preadipocytes, acute hypoxia induced a 6-fold reduction in lipoprotein lipase activity. In humans, the rise in postprandial triglyceride levels did not differ between normoxia and intermittent hypoxia. Non-esterified fatty acid levels were higher during intermittent hypoxia session. Intermittent hypoxia did not affect subcutaneous abdominal adipose tissue lipoprotein lipase activity. No differences were observed in lipolytic responses of isolated subcutaneous abdominal adipocytes between normoxia and intermittent hypoxia sessions. Conclusions: Acute hypoxia strongly inhibits lipoprotein lipase activity in differentiated human preadipocytes. Acute intermittent hypoxia increases circulating plasma non-esterified fatty acid in young healthy men, but does not seem to affect postprandial triglyceride levels, nor subcutaneous abdominal adipose tissue lipoprotein lipase activity and adipocyte lipolysis.