Are there nutrition suggestions for preventing or slowing myeloma?

A lot of the usual keep-healthy stuff. Healthy diet, exercise (resistance training if aerobic is difficult), normal weight (obesity is implicated in some other cancers and health conditions. MM, who knows?), avoid stress, hydrate, get enough sleep. I have MGUS and take bioavailable curcumin twice a day with meals (best absorbed with food with a bit of fat). Some take regular curcumin with black pepper (although the peperine in pepper can increase intestinal permeability [leaky gut in those of us with celiac]). Tumeric and curcumin are poorly absorbed by the GI tract, so "bioavailable" and peperine increase absorption. It is common enought it is at Walmart. At least in research tests, the curcumin suppresses tumor growth (TNF). Does it work in us? I don't think there is enough info yet (I'm a scientist) but I'm fine with being a lab rat. Check to make sure it doesn't interfere with meds or other health stuff. Search using "MGUS curcumin," Here are a few links.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10061533/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3445886/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9301229/

Everyone is different. It is best to find a good nutritionist and submit your blood work to them so that they can craft a program to suit your needs. Changing my diet and the vitamins and supplements I take is expensive however all of my blood work has improved. Good luck!

What’s your diet, vitamins, supplements now?

Basically an organic foods anti inflammatory diet.