Supplemental calcium (but not dietary calcium) can increase your risk of kidney stones, especially if coupled with supplemental vit D
https://en.m.wikipedia.org/wiki/Kidney_stone#Diagnosis
In the early 1990s, a study conducted for the Women's Health Initiative in the US found that postmenopausal women who consumed 1000 mg of supplemental calcium and 400 international units of vitamin D per day for seven years had a 17% higher risk of developing kidney stones than subjects taking a placebo.[21] The Nurses' Health Study also showed an association between supplemental calcium intake and kidney stone formation.[4]
I have also heard that calcium citrate supplements are better than calcium carbonate ones as citrate is a natural inhibitor of stone formation. I'll have to dig through for the source.
So if you can have a dietary calcium source (rather than supplement) that might be a better option. Also, majority of kidney stones are calcium oxalate, so don't depend on oxalate rich foods for your sources of calcium. Kale, mustard greens, brocolli would be better.
https://en.m.wikipedia.org/wiki/Calcium ... ney_stones
About 80% of kidney stones are partially or entirely of the calcium oxalate type. They form when urine has been persistently acidic. Some of the oxalate in urine is produced by the body. Calcium and oxalate in the diet play a part, but are not the only factors that affect the formation of calcium oxalate stones.
Of course only some people might face issues with supplements/oxalate rich diets so may not be a reason to avoid them/not meet your calcium RDA. If you are to get a supplement, choose a routinely used vegan brand, maybe calcium citrate though other alternatives may also be OK. If I remember correctly Gregger is OK with calcium carbonate.
http://bitesizevegan.com/vegan-health/g ... facts-org/
I still wonder why some studies show that the countries with the biggest dairy product ingest have the biggest rates of osteoporosis.
As far as osteoporosis is concerned, the discrepancy in studies AFAIK is actually incorrect/misrepresented. Rather than hip fracture, a more accurate measure is vertebral fracture which it turns oioiut does correlate with dietary calcium, Asians actually are worse off than milk guzzling Caucasians. Also it would appear there's more of an issue for women than men.
http://www.veganhealth.org/articles/bones
Epidemiological studies
The observed ethnic differences in fracture incidences may be due to the fact that hip fracture risk was affected by fall risk, whereas the risk of vertebral fracture mostly depends on bone strength. Despite the low hip fracture rate in our population, Hong Kong women had a higher prevalence of osteoporosis [technical parenthetical deleted] than US Caucasian women (35.8% vs. 20%, respectively) and a similar prevalence of about 6% in Hong Kong and US Caucasian men.
You know how it is with medicine and science too... one day they say chocolate is good for you, and the next day they take it away lol
This is actually blatant misrepresentation of science, its an anti science confusionists tactic that's employed by many sciemce denialists/pseudoscience apologists like creationists, nutrition confusionists etc. Generally while there are exceptions (often for valid methodological reasons), generally the more scientific studies on the subject, the more we wind up narrowing down to one conclusion rather than multiple mutually contradictory results as the anti sciencers/ignorsnt like to paint it. That's why when you look at meta analyses rather than the next new study, one arrives closer at a single conclusion. The "science iss constantly contradicting itself" myth is as a result of such confusionists/ignorant people and also due to the way science results reporting is conducted by the ignorant press who just report the next new study rather than reporting it in the context of a meta analysis/lit survey.
This is a very good article on the subject:
http://www.vox.com/2015/3/23/8264355/re ... study-hype
See image2.
While it's true, that studies have shown everything causes and prevents cancer as is reported by the press, if you look at the picture carefully, you can see that most studies show wine/tomatoes as protective while beef is the stark opposite. Also the scales are off so beef is actually much worse. But shoddy press reporting and myth spreading mean some folks would conclude beef and tomatoes are in the same league.