I just read that yes iron absorption can be lowerd by calcium intake. They recommended that you take the supplement at bedtime or in the morning and not with the iron or food containing iron, especially if you are iron deficient and need extra iron. If you are very low in iron then I would take a higher dose than that which is in beets. If not then it is probably ok if you separate the time you take the supplements and/or beets in this case.
hope this helps.
mkh9
beets are from food not some pill