I am an avid gardener living in sunny California. You cannot get enough vitamin D3 from the sun anymore because of too much particulate in the air. When I got my vitamin D3 level checked, it was an abysmal 3 ng/ml. My DEXA scan came back at -5.7 (serious osteoporosis is -2.5). This loss of calcium in my bones came about because of a pituitary tumor that caused serious hormonal deficiencies, more specifically a loss of human growth hormone. The tumor and HGH deficiency were not detected until I was 61 years of age. I went back on estrogen (low dose) and progesterone at age 68, as well as supplementation of Human Growth Hormone. I take 1200 mg calcium (600 mg in morning and 600 mg at night) with 2,000 IU of vitamin D3, Vitamin K2, boron, and 500 mg of magnesium. You MUST take Vitamin K2 or your calcium will wind up in your arteries instead of your bones! I take these supplements two hours away from anything else I am taking to avoid interactions. I eat piles and piles of kale and arugula with sliced almonds and pieces of cheese. I am lactose intolerant, so I take digestive enzymes to get the cheese in me. I eat salmon three times a week. Try to eat as much calcium as you can and subtract the mg of calcium you are getting from your daily total. (I have a kidney stone, so I have to watch that I don't get excessive amounts.). ConsumerLab has thousands of medical journal articles about supplements posted for you to read and they test to be sure your supplements are exactly what they say they are and nothing extra (e.g., lead, etc.). I have also increased the amount I walk each day in an effort to increase my bone strength. I take this very seriously as I have started fracturing. I just can't do sardines. I am avoiding the drugs like Prolia after speaking with woman who took it and have irreversible, devastating side effects (osteonecrosis of the jaw, etc.). Also, when you go off the drugs like Fosamax and Prolia, the new bone you made suddenly disappears. Those drugs seem to me to be very dangerous. I am getting a new DEXA scan early in 2020, and I'll try to remember to come back and give an update. I have only been on this regimen the past six months, but even a modest reversal of my bone loss would encourage me. Good luck, everybody!