Updated: May 9, 2020
Calcium is usually the first supplement that comes to mind first when we hear about bone health.
It's may be hard to believe based on the ubiquity of the message '1200mg per day for bone health!' that these standards were based on studies that lasted a few week in the 1970s, and were first recommended in 1997 .
While we need calcium, particularly past 50 years of age, it's important that you don't grab any old supplement off the shelf and that you pay close attention to dosage.
There are many ways that lifestyle, diet and other nutrients besides calcium can help sustain healthy bones throughout your life.
Here are some potentially dangerous side effects of calcium supplementation.
1. Heavy Metal Contamination
The presence of heavy metals, particularly lead, in calcium supplements has been well documented since the 90s. 
These heavy metals can accumulate in your body and slowly overwhelm the organs responsible for filtering out toxins.
The presence of heavy metals in tissues and organs have been implicated in the development of cancers and chronic illness. 
The best and cleanest source of calcium supplementation is bovine hydroxyapatite that is certified organic and sourced from New Zealand. It is also the best absorbed by the body.
Potential Side Effects Of Heavy Metal Toxicity
Read more about Toxicity
2. Too Much Calcium Is Dangerous, Especially For Men
Many assert that the daily recommended dose of 1200mg of calcium is too high, and that we would do well with half that amount. 
The reason is that calcium (and vitamin d for that matter) are not protective against bone fractures at any dose, at any age, and taking more than the recommended dose could poison your body with an excess of calcium. 
Particularly in the case of calcium supplementation for men, more is not better. The risk of 'high grade' and advanced stage prostate cancers increase with more than 2,000mg daily intake 
Keep in mind that this data only is looking at bone fractures, in the case of risk reduction for certain diseases or reversing deficiencies, the right calcium supplement could be very effective.
As always, it is never advisable to piece together your own treatment plan. A functional medicine doctor can help you choose the right high-grade supplementation as a part of your overall health goals.
Symptoms of Too Much Calcium (Hypercalcemia)
excessive thirst, frequent urination
stomach pain, cramping
bone and muscle pain
irregular heart beat/palpitations
3. Increased Risk Of Stroke & Heart Attack
There is a sizable debate whether calcium supplementation causes heart attacks and stroke, with many recent studies as coming up as inconclusive.
When there is determined to be a risk, it is when calcium is taken alone. When calcium is supplemented with vitamin D, this additional risk of heart attack and stroke seems to go away. 
I believe that this excess calcium builds up in the arteries which is responsible for the increased risk of stroke or heart attack.
I would ensure that my patients who needed to take calcium also take vitamin D3 and K2 (specifically menaquinone-7, approximately 300mcg per day).
Taking vitamin D3 and K3 ensures that the calcium will be deposited in your bones and not in your