It would be better to eat Kelp or another seaweed instead of just supplementing on one or two minerals. Kelp and other seaweeds have like 80 minerals that your body needs. Blackstrap molasses is good for macro (major) minerals.
Also, I don't seem to have a problem with insulin spikes. I can eat very large meals with pasta and potatoes and be okay. I've only had a problem of gaining weight (insulin spikes) from drinking lots of juice in the past. It depends on your specific body.