High-dose calcium supplements have been linked to heart risks. Are calcium-fortified foods any better?
High-dose calcium supplements have been linked to heart risks. Are calcium-fortified foods any better?
Nutrition Diva is hosted by Monica Reinagel. A transcript is available at Simplecast.
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Hello and welcome to the Nutrition Diva podcast. This week’s episode was suggested by a listener who wrote in with concerns about calcium.
“My doctor has advised me to take 1200 mg of calcium a day. But I’ve read that the calcium from supplements can end up in your arteries. Is eating calcium-fortified foods the same as taking a calcium supplement? Or is it best to get calcium only from foods that contain it naturally?”
Lots to unpack here. The recommended daily allowance for calcium for women over 50 is 1200 mg. And a lot of women (and their doctors) interpret that to mean a 1200 mg calcium supplement. If you go to the vitamin aisle of the drug store, you will see lots of bottles of calcium marked 1200 mg.
By the way, even if the bottle says 1000 or 1200 mg, that doesn’t necessarily mean that each pill contains that much. You need to check the dosage instructions, which are in that teeny tiny type on the back of the bottle. Often, it takes 2 or 3 tablets to get the amount listed on the front of the bottle. But almost no one needs to be taking that much calcium in supplement form.
The typical diet provides around 250 mg of calcium—not counting dairy products. If you consume dairy products, it’s likely to be quite a bit higher than that. Each serving of dairy provides another 250 to 300 mg.
Other foods, such as tofu and certain vegetables, can contribute significant amounts of calcium as well. And any calcium-fortified products (such as nondairy milk alternatives, orange juice, and some cereals) contribute even more.
So, depending on your eating habits, it’s entirely possible that you are getting the recommended amount of calcium without needing any supplements at all.
Calcium-fortified foods typically use the same form of calcium as you’ll find in the most common calcium supplements. But getting that calcium from a fortified food instead of a pill does offer some advantages. It means that you’re getting your calcium in smaller amounts spread out over the day, more the way you would if you were getting it from natural food sources. And the presence of other nutrients in that food may facilitate better digestion and absorption.
The reason that calcium supplements have been linked to arterial calcification is not really because of the form of the calcium, or even the fact that it is being taken as a supplement as opposed to foods. It’s because people taking calcium supplements (such as those 1200 mg pills you’ll see at the drug store) often end up taking in way more than the recommended daily intake of calcium.
Studies have found that women who take in more than 1400 mg of calcium a day have a higher rate of heart attacks and a markedly higher risk of death from cardiovascular disease. Women rarely get this much calcium from diet alone; there’s almost always a supplement involved. But if you are taking a 1000 or 1200 mg calcium supplement, you are very likely to be taking in more than 1400 mg a day, once you account for the calcium in your diet.
I know we’re all worried about osteoporosis. I also know that many doctors and gynecologists are still advising their older female patients to take 1000 to 1200 mg of supplemental calcium a day. With all due respect to my medical colleagues, this my not be the best advice. You can’t make up for the calcium you failed to get during your teens and 20s by doubling up in your 40s and 50s.
The concerns about overdoing it with calcium supplementation don’t just apply to women. High-dose calcium supplements increase your risk of painful kidney stones. It’s also been shown to increase the risk of developing polyps in your colon—especially if you have had polyps in the past.
It’s important to point out that polyps are not cancerous—but they can eventually turn into cancer if they are not removed. This is why those screening colonoscopies are so important. Catching and removing these relatively benign polyps before they can become malignant can save your life.
But even if it doesn’t lead to cancer, taking a supplement that increases the occurrence of colon polyps may lead to unnecessary medical costs and risks due to more frequent screening and removal of the polyps.
Here’s the take-home message: If you’re eating a healthy diet, you really shouldn’t need more than 250 – 500 mg of supplemental calcium. You may not need any at all.
Dairy products like milk and yogurt are among the most concentrated dietary sources of calcium and the calcium in dairy products is very well absorbed. Dairy products are also good sources of magnesium and phosphorus and most are fortified with vitamin D. All of these help your body make the best use of calcium.
Each eight-ounce serving of milk or yogurt contains about ¼ to 1/3 of your daily calcium needs. And, as I mentioned earlier, many nondairy milk alternatives are fortified with calcium to bring them up to the same level as cow’s milk.
But you have lots of other options, as well.
Fish such as sardines and canned salmon are great sources of calcium because they contain tiny bones that are so soft you’d never notice them, but that are a potent source of calcium. As a bonus, these fish are also among the few natural food sources of vitamin D. Getting tons of calcium is not nearly as effective as simply getting the recommended amounts of calcium and Vitamin D.
Tofu can be an excellent source of calcium because it’s usually made with calcium sulfate as a natural setting agent. Tofu is also a good source of protein, which enhances calcium absorption and bone health. A half cup of firm tofu can provide half a day’s supply of calcium.
Vegetables in the cabbage family, including broccoli, kale, bok choy, cabbage, mustard, and turnip greens are all good sources of calcium that are very bioavailable. Cabbages and leafy greens are also good sources of folate and vitamin K, nutrients that also help build strong bones. A half cup of Chinese cabbage or a cup of bok choy provides almost as much absorbable calcium as a glass of milk.
Not all food-based calcium is well-absorbed. Spinach, for example, contains quite a bit of calcium but it also contains a lot of oxalates. These natural compounds bind with calcium and make it very difficult for your body to get at it. Although spinach has a lot of good stuff going for it, it’s not a great source of calcium. In fact, because the oxalates in spinach can bind to the calcium in other foods as well, it can even keep you from getting as much calcium from the foods that you eat with it. Unless you never eat calcium-rich foods except with spinach, this is not a big deal—just something to keep in mind.
To get a rough estimate of how much calcium you’re getting, start with 250 milligrams as your baseline. Add 250 mg for each serving of dairy, canned fish, tofu, Chinese cabbage, or fortified orange juice or nondairy milk. Give yourself another 100 for each serving of any other cabbage family vegetables.
It’s not important that you get exactly 1000 mg of calcium every day—if it’s averaging out to your recommended intake, you’re probably getting all the calcium you need.
But if you still need a supplement to close the gap between the recommended intake and your diet, it’s likely to be a much smaller dose than 1200 mg.
I hope that sets the record straight on calcium supplements, calcium-fortified foods, and natural sources of calcium.
With any decision regarding drugs or supplements, you need to weigh the potential benefits (including how big the benefit might be, how likely the benefit might be, and the strength of the evidence supporting those) against potential risks (including cost, the severity and likelihood of side effects or other complications.) All of that has to be filtered through personal considerations, such as any current diagnosis as well as personal and family medical history and risk factors. The best person to help you assess the pros and cons is your doctor.
If you have a question you'd like me to answer, you can email me at nutrition@quickanddirtytips.com You can also leave me a message at 443-961-6206
I’d also like to invite you to check out my other podcast. It’s called the Change Academy, where we explore the art and science of creating positive behavior change, both in our own lives and in our workplaces and communities. You can find it on all the major podcast platforms. Just search for Change Academy.
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That's all for this episode. Thanks for listening! I'll see you next week.