Based on my readings, I think it is overwhelmingly clear that the rise in triglycerides, the increased visceral adiposity (and concomitant insulin resistance and hypertension), and whatever other ill effects fructose has on humans is the result of malabsorption and selective fermentation by ‘bad bugs’ which produce various toxins (such as endotoxin) which we then absorb. Foods with digestive inhibitors, such as legumes and certain grains, may lead to a similar rise in endotoxin due to their inhibiting of the digestion of our foods.
My understanding with foods (or at least with carbs/protein/fat/alcohol/fibers/synthetic sweeteners/etc.) is that fermentation by bacteria WILL HAPPEN when we malabsorb the food. The result (good or bad) depends on the selectivity of the feeding. ‘Resistant starch’ and ‘inulin’ tend to feed ‘probiotic’ bifidobacteria and increase healthful substrates like butyrate and other short chain fats. Conversely, fructose, alcohol, (and other things) if malabsorbed will selectively feed ‘bad bugs’ and increase endotoxin absorption which goes to the liver and places a massive energy burden on the liver to detox the endotoxin. If the liver is given extra energy via, for example, short chain fats like MCTs and vinegar, the systemic effects of the endotoxemia are lessened. This, I think, is one of the reasons vinegar lowers postprandial glucose in diabetics and pre-diabetics (it helps the liver cope with postprandial endotoxemia).
As an aside to this last point, I one time recommended my med school roommate take some apple cider vinegar capsules and coconut oil right before he went out drinking. He is a small Asian guy who said he normally feels ?buzzed? after one beer. Well, I challenged him to see how much he could drink by taking some ACV and MCTs. I had him take 10 ACV caps and 20g coconut oil. He said he got up to 6 beers and stopped because he thought he should, but felt nothing. I am not a drinker, but I think this is a proof of principle: supporting the liver’s energy status with short chain fats and absorbable carbs can eliminate most negative effects of malabsorbed foods. But better would be to absorb the food properly in the first place!
In any case, specific to fructose, provided it is absorbed, it’s all good. And making sure you eat enough glucose WITH the fructose will help most absorb the fructose without problem. The exact mechanism of this is not worked out, but appears to involve a ‘cotransport’ mechanism by which one molecule each of fructose and glucose are carried together.