A.  Take Home Message.

Prostate cancer

[PCa] research overwhelmingly suggests that a high calcium intake, whether from dairy or supplements, is associated with more aggressive PCa.

The likely reason is that excess calcium inhibits the conversion of circulating inactive vitamin D to its active hormonal form.  This is very important, since PCa loses the ability to make that conversion from within the cell.

Osteoporosis is often not due to calcium insufficiency, but to a deficiency of vitamin K (preferrably obtained in the K2-7 form), which is required for the transportation of calcium to bone.  Without adequate vitamin K, calcium will be deposited on arterial walls or excreted. 

I do not use a calcium supplement, but I would never go above 500 mg / day.

Milk should be avoided, except perhaps for a small amount in tea & coffee.  If cheese has to be eaten, ignore the low-fat varieties.  The high-fat, such as the triple cremes, have far less calcium, & one is not likely to over-indulge.  

If osteoporosis is a concern, the following co-factors should be taken with calcium: magnesium, zinc, boron, vitamin D, vitamin K2.  (Be wary of lists that include copper.)

If the osteoporosis is due to androgen therapy, a low-dose estrogen patch can bring estradiol up to the level required for bone health (12 pg/mL)

B.  Introduction.

In the days before farming, hunter-gatherer societies obtained all the calcium they needed from plant sources – no dairy; no supplements.

Vegetable sources include greens, which also come with the vitamin K needed for transportation to bone.

In 2013, the U.S. Preventive Services Task Force came out against calcium being effective against avoiding fractures