Monday, April 22, 2013

Everyone Needs Calcium. Where Should You Get It?

On February 15, I wrote a blog titled Calcium and Heart Disease: What's the Story? Here is the link if you want to review it.

That blog highlighted the possible dangers of taking calcium supplements and added that "the bottom line is everyone needs calcium and it is best and safest to get it from foods like broccoli, almonds, tofu, sardines, kale and other leafy vegetables, and almond milk. As I am not a fan of dairy, I don't recommend dairy products but Greek yogurt, etc. are also good sources of calcium."

I didn't spend  a lot of time in that blog discussing one of the other potential dangers of taking calcium supplements, which is the development of the most common type of kidney stone made from calcium oxalate. 

To mostly quote and sometimes paraphrase an article that appeared in MedlinePlus, here's the latest understanding of the role of calcium in kidney stones.

Scientists knew that getting lots of calcium from foods lowers the likelihood of kidney stones in those most at risk, but thought that it may only be true for calcium in milk.  Well a new study makes clear the benefit isn't just linked to milk products.

So first the good news. In a large new analysis, men and women who consumed the most dietary calcium from foods had about 20 percent lower risk of developing kidney stones than those who consumed the least calcium. The key takeaway is unlike calcium in pill form, don't avoid calcium in food as it is good for you.

"This is another piece of data to suggest that there's no role for dietary calcium restriction for kidney stones," said lead study author Dr. Eric Taylor, a kidney specialist at Maine Medical Center in Portland.  As stated earlier, most stones that form in the kidneys are made of calcium oxalate and past studies have found that eating calcium-rich foods - though not taking calcium supplements - seems to ward off stone formation."

Since most people typically got their calcium primarily from dairy products, "there was lingering doubt about whether some other component of milk might be responsible for the effect." To address this question, Taylor and his colleagues set out to see whether the results held true for calcium from non-dairy foods. To do so, they "analyzed data from three large studies that followed more than one million men and women, sometimes for decades, and included periodic detailed food questionnaires.
The researchers divided those participants into five smaller groups, based on how much calcium they consumed from dairy and other sources over as long as 20 years.

Only participants who were generally healthy and had never suffered from a kidney stone before dietary data collection began were included."

More good news. "For both dairy and non-dairy sources of calcium, people who consumed the most calcium were least likely to develop painful, symptomatic kidney stones - overall, their risk was 77 percent of that seen among people who ate the least calcium, Taylor's team reports in the Journal of Urology....

For non-dairy foods, people who consumed 250 milligrams of calcium a day - the amount in eight ounces of cooked kale or two sardines, for example - were twice as likely to develop a stone as people who got 450 milligrams daily.

Rates of kidney stones in the U.S. translate to the average person having a 6 percent chance of developing a stone during a lifetime. So, in the new study, low calcium consumption doubled that risk to 12 percent."

But here's the kicker. "Because most kidney stones are made of calcium oxalate, it might seem counter-intuitive to consume more calcium and end up with less in your kidneys, but there is theory about why it works...The real culprit is oxalate, not calcium. Oxalate is found in many foods including fruits, vegetables, nuts and chocolate, and calcium binds to it avidly. The more calcium in the digestive tract, she said, the more oxalate it can bind and take out of the body before the oxalate is absorbed into the bloodstream and ends up in the kidneys and bile duct.

Here's the bad news. Many patients don't understand this relationship and cut back on calcium anyway, which actually increases their risk, according to Dr. Mathew Sorensen, a urologist at the University of Washington in Seattle.
"I see patients every week, and most have cut back on their calcium intake," Sorensen told Reuters Health in an email. "It is one of the most important myths in the stones world that needs to be corrected."
Really excessive calcium levels aren't a good idea either, Sorensen said. He recommends patients keep levels moderate, around 1000 to 1200 milligrams per day."

So let's summarize.
1. You need calcium in your diet as it is one of the 15 essential minerals.
2. Dietary calcium binds oxalate in your intestinal tract to reduce oxalate's absorption into your blood stream, which reduces your risk for developing calcium oxalate kidney stones.
3. If you can avoid kidney stones and the sudden and very painful problems they cause, you should absolutely try to do so.
4. It is best to get your calcium from food in reasonable amounts as it is considered safe to get your calcium from dietary sources.
5. While milk and other dairy products are known sources of calcium, there are healthier alternatives such as almond milk, (Silk Brand, Unsweetened, is recommended) to get adequate calcium.
6. Calcium supplements remain a potentially dangerous source of calcium, whether or not taken with magnesium.

If you know of a doctor who continues to recommend calcium supplement pills, please ask him or her to review their information because it is out of date. Maybe you can even educate them. For me, an educated patient is my favorite type.

1 comment:

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