Can I get too much vitamin D?
Too much of any good thing is a bad thing. Too much vitamin D can cause an abnormally high bloodcalcium level, which could result in nausea, constipation, confusion, abnormal heart rhythm, and even kidney stones.
It's nearly impossible to get too much vitamin D from sunlight or from foods (unless you take way too much cod liver oil). Nearly all vitamin D overdoses come from supplements.
The Institute of Medicine's Food and Nutrition Board's old 1997 recommendations...
Exercise is important in both the prevention and treatment of osteoporosis. If you’ve been diagnosed with osteoporosis, starting a regular exercise program may help prevent further bone loss. Lack of exercise is a major risk factor for bone loss. You can’t change your sex, age, or family history. You can change your exercise habits.
Along with keeping bones strong, exercise strengthens muscles, gives joints more support, and keeps your joints flexible and limber. If you’ve already had one fracture, exercise and activity may help to shorten the time of recovery and decrease the amount of pain you feel. But always talk to your health care provider before starting a new exercise program and following a fracture.
Exercise can also keep you balanced and flexible. As people age, the risk of falls becomes greater, and falling is a key risk factor for fractures? But having good balance and being flexible can protect you against falling. It will also help if you go through your house and yard and make sure they’re "fall-proof."
Somewhere between ages 30 and 40, many of us become less active because our jobs are sedentary. As we pass 50, this tendency to be sedentary generally increases. This can be a big problem, especially if other risk factors for osteoporosis develop.
If you work at a sedentary job all day and find that exercise and physical activity are becoming a smaller part of your normal lifestyle, you can do something. Add periods of physical activity throughout your day to help keep bones strong.
How important is it to be physically active? Some interesting studies have shown that a marked decrease in physical activity, for example in people with prolonged bed rest, results in profound decline in bone mass. A prime example of what can happen can be found in the bone disorders of astronauts. Tests on astronauts who experience weightlessness show the necessity of weight bearing activity for keeping bones strong.