Prostate cancer patients who take extra calcium 'could be making their condition worse'
07:18 GMT, 8 August 2012
Prostate cancer sufferers who take calcium supplements to protect against bone loss caused by treatment could be making their condition worse, warn researchers.
A review of trial data concluded the supplements do not improve bone strength and may increase the risk of heart disease and more aggressive cancer.
At least 5,000 men with prostate cancer are given hormonal therapy each year in the UK. It works by blocking the production of male hormones, but it also makes fractures more likely.
Condition: Prostate cancer patients who take calcium supplements may be increasing their risk of heart disease, researchers have found. (Picture posed by models)
US researchers reviewed guidelines for calcium and vitamin D supplementation, taking measurements of bone density before and after the men were prescribed hormonal therapy.
The study, reported in journal The Oncologist, showed that at the calcium doses commonly recommended, their bones got thinner.
Its authors, at Wake Forest Baptist Medical Center, North Carolina, said other studies show a link between increased calcium and a higher risk of aggressive prostate cancer and heart disease.
Mridul Datta, co-author of the study, said ‘Calcium and/or vitamin D supplementation to prevent loss of bone mineral density in these men seems so logical that no one had questioned whether it works.
'We used these data to determine whether calcium and vitamin D supplements prevented bone loss in these men.
‘The answer clearly is, “No”.'
Dr Schwarz said other research shows a link between between increased dietary calcium and a greater risk of aggressive prostate cancer and heart disease.
It is not clear why some studies show high calcium levels fuel the progression of prostate cancer, but it may be due to an interaction with the active form of vitamin D in the blood that helps prevent development of cancerous cells.
Research last year suggested women taking extra calcium might be at higher risk of heart attacks and strokes.
Findings: A thermograph showing prostate cancer. A study has found that patients who take calcium supplements could be making their condition worse
Dr Datta said: ‘The wakeup call of these findings is that the presumption of benefit from calcium and vitamin D supplements that have been routinely recommended to these men must be rigorously evaluated.’
But Dr Kate Holmes, of Prostate Cancer UK, said further research was required, as the authors did not look at studies comparing patients given calcium supplements with those who were not.
‘Although this review suggests that men who are taking supplementary calcium whilst on hormone therapy are not benefiting in terms of bone health, and may in fact be putting their overall health at greater risk, there is not sufficient evidence on the effects of calcium intake on bone health to reach any firm conclusions.
‘It is certainly true that other health and safety issues should be considered before men increase their intake of dietary calcium.
'However as no studies were reviewed which compared calcium supplementation to no calcium supplementation, which would give the clearest idea of its effects, further studies are required to establish whether increasing calcium intake during hormone therapy leads to better bone health or not.
‘We would encourage anyone who has concerns about their calcium intake to consult their doctor about their individual situation.’
The Food Standards Agency recommends adults have 700mg of calcium a day, which should come from dietary sources including milk, cheese and green, leafy vegetables.