BD through a J-tube can certainly be done, but as with all things, not necessarily by everyone.
I can't eat orally, or indeed swallow at all, and quite a while back I was very interested in questions around whether I was missing out on some vital part of digestion by lack of saliva getting on down there. Turns out, not really. A little more recently, much has been discussed about PPIs (proton pump inhibitors - medicines like Prevacid and Nexium) and their possible effect on digestion by changing the acidity of the stomach. The jury's out on that. This was around the same time as a nutritionist enlightened me to the school of thought about not consuming water while you eat (or feed) because it dilutes the stomach secretions - acids and enzymes mostly. I got to thinking, and asking, and what I wanted to know was: what are these secretions like saliva, stomach enzymes and acids actually doing to the food we ingest?
Turns out, they're essentially doing what my Vitamix does. Saliva is to help the food be chewed and go down the esophagus. The enzymes are like little keys that 'unlock' proteins and other components into smaller molecules, and the acids attack larger clumps of chewed-up stuff and turn it into a more liquidy substance that the intestines can deal with more easily. Now the Vitamix doesn't quite do the whole job the enzymes do, but I'd say it gets you about halfway there. A high-powered blender with blunt blades like the Blendtec or the Vitamix not only liquidizes food far better than your jaw muscles, tongue, teeth and stomach acids can, but smashes apart cell walls of both animal and vegetable tissue to release nutrients locked inside those cells. Cooking can do a similar thing, but often destroys much of the nutrients in the process. Enzymes do this work in our stomachs.
So here's my hypothesis: That may blends made in a high-powered, high-speed blender are probably pre-digested enough to be fed into a J-tube, with possibly a better chance of success the higher (ie towards or in the duodenum) the J is placed.
If it were me, there would be some things I'd steer away from, mainly things that need our stomach acids to neutralise or curdle. Dairy, fish, shellfish, chocolate, tomatoes and maybe broccoli and potato too. Then again, it's entirely possible that all these would do just fine.
People are a little more nervous of J-tubes for other reasons too. They sometimes have no internal retainer (in the case of separately sited J-tubes, as opposed to GJs) so are more prone to slippage, leakage and anecdotally anyway to infection. I'm willing to bet they're a bit more uncomfortable to have than a G-tube - anyone? And their ends just dangle there inside, and so you can never be 100% sure exactly where they are. But really, I think these are not cause to be any more nervous about what food you put down there.
There are not very many people doing J-tube feeds with BD right now. More are coming to light though, and as I discover more personal examples, I can add them in here. I really don't see any risk in trying a basic, easy-to-digest blend, preferably of vegetable substances (veges, fruits, grains) first that are known to be tolerated, and going as one would for an infant eating for the first time; add one new ingredient at a time, and go slowly.
If I had a J-tube, I'd give it a go. But that's the thing isn't it? I could also just jump in to BD with my g-tube because if anything 'went wrong', I knew I would deal with it, it was my body, I could feel things - not like a watchful, nervous parent or carer. That's harder, no doubt. Still, there are people that do it, and doctors that say there's no reason you couldn't. The human body is after all amazingly adaptable, and we were built for food.
Food for thought! It's worth remembering that medicine is a very conservative institution. The status quo is 'safe', and of course patient safety (and doctor's safety too of course) is paramount. There are no incentives to question the things they've always been trained to say no to. Some doctors say go for it, give it a try, can't hurt. Others say no, no way, never. We only discover through trying. But it's you who must decide whether to try or not.