I have a great deal of respect for Lustig’s professional accomplishments, and I share his concern for the nation’s penchant for sitting around and overconsuming food and beverages of all sorts. However, I disagree (as does the bulk of the research) with his myopic, militant focus on fructose avoidance. He’s missing the forest while barking up a single tree. So, what’s the upper safe limit of fructose per day (all sources considered)? Again, this depends on a number of variables, not the least of which are an individual’s physical activity level and lean body mass. Currently in the literature is a liberal camp reporting that fructose intakes up to 90 grams per day have a beneficial effect on HbA(1c), and no significant effects are seen for fasting triacylglycerol or body weight with intakes up to 100 grams per day in adults [15]. The conservative camp suggests that the safe range is much less than this; roughly 25-40 grams per day [19]. Figuring that both sides are biased, the middle figure between the two camps is roughly 50 grams for active adults.
Although the tendency is to get hung up on the trivial minutia of an exact gram amount, it’s not possible to issue a universal number because individual circumstances vary widely (this is a concept that baffles anti-fructose absolutists). The big picture solution is in managing total caloric balance with a predominance of minimally refined foods and sufficient physical activity. Pointing the finger at fructose while dismissing dosage and context is like saying that exercise should be avoided because it makes you fat and injured by spiking your appetite and hurting your joints.
