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Doc: Do calcium-channel blockers block supplements?

Keith Roach
To Your Health

Dear Dr. Roach: My doctor put me on Norvasc 10 mg to keep my blood pressure normal. Since Norvasc is a calcium-channel-blocking medicine, can I still take my calcium and vitamin D-3 supplements? I was advised by my gynecologist that I should take calcium every day for my bones and D-3 by my general practitioner. The research I have done says the intake of supplemental calcium from tablets will cut the effectiveness of the channel-blocking amlodipine because my circulating calcium will be higher. Should I take the supplements?

I.H.

Dear I.H.: The body has powerful mechanisms to keep the calcium level in the blood at a regulated level. A small change in blood calcium leads to dramatic changes in physiology. For people who don’t take in enough calcium, one tool the body has is to break down bone for the large supply of calcium there. That’s not good for long-term bone health, which is why adequate calcium intake is recommended. That can be either from diet or from supplements, but since supplements increase the risk of kidney stones and may increase the risk of heart disease, dietary calcium is preferred. I recommend calcium supplements only for people who can’t get enough from their diet and who have or are at high risk for osteoporosis. Oral calcium, whether from diet or supplements, does not increase blood calcium levels, but it does reduce or reverse calcium flow out of bones.

Calcium-channel blockers, used for hypertension, heart disease and other conditions (like Raynaud’s and for some people with migraine) affect the flow of calcium into muscle cells. For high blood pressure, this means relaxing the smooth muscle in blood vessels. They are capable of doing so at normal blood calcium levels, so oral calcium supplements do not significantly reduce their effectiveness.

Similarly, normal doses of vitamin D-3 (4,000 IU a day or less) do not significantly affect calcium levels, and may be taken with calcium-channel blockers.

Dear Dr. Roach: I’ve seen articles claiming rapid weight loss while taking CLA safflower oil. Is this true?

A.A.

Dear A.A.: CLA and safflower oil are not the same thing. Safflower oil is not a good source of conjugated linoleic acid. One study compared the two in overweight postmenopausal women with diabetes, but while the safflower oil group had some favorable changes in body composition, neither group showed rapid weight loss. Other studies have shown, at best, minimal weight loss. I don’t recommend either for weight loss.

Email questions to ToYourGoodHealth@med.cornell.edu.