I didn't think sugar (sucrose = glucose + fructose) was present in breast milk, I thought it was mostly lactose which doesn't contain fructose. Turns out there is a little fructose, and only a little lactose in breast milk. It's mostly glucose.

But the concentration of fructose in breast milk seems directly correlated to the weight gain and fat gain in infants by 6 months of age.. It also correlates with lean mass and bone mass. So it's kinda hard to say if its a good or a bad thing, at least in breast milk.

This study was from 2017--


https://www.google.com/url?sa=t&rct...2xdFZrfYxfLzrGC

"Dietary sugars have been shown to promote excess adiposity among children and adults; however, no study has examined fructose in human milk and its effects on body composition during infancy. Twenty-five mother–infant dyads attended clinical visits to the Oklahoma Health Sciences Center at 1 and 6 months of infant age. Infants were exclusively breastfed for 6 months and sugars in breast milk (i.e., fructose, glucose, lactose) were measured by Liquid chromatography-mass spectrometry (LC-MS/MS) and glucose oxidase. Infant body composition was assessed using dual-energy X-ray absorptiometry at 1 and 6 months. Multiple linear regression was used to examine associations between breast milk sugars and infant body composition at 6 months of age. Fructose, glucose, and lactose were present in breast milk and stable across visits (means = 6.7 μg/mL, 255.2 μg/mL, and 7.6 g/dL, respectively). Despite its very low concentration, fructose was the only sugar significantly associated with infant body composition. A 1-μg/mL higher breast milk fructose was associated with a 257 g higher body weight (p = 0.02), 170 g higher lean mass (p = 0.01), 131 g higher fat mass (p = 0.05), and 5 g higher bone mineral content (p = 0.03). In conclusion, fructose is detectable in human breast milk and is positively associated with all components of body composition at 6 months of age."