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Fitness Files: Caffeine and its effect on bone density

Along with Sunday morning coffee, my newspaper reading is too often interrupted with runs to the bathroom — which led me to wonder if the diuretic effect of coffee is flushing the vitamins and minerals from my breakfast of organic orange, banana and oatmeal down the toilet.

Since osteoporosis is on my mind, this WebMd article attracted my attention: "Osteoporosis Diet Dangers." After strong warnings about salt intake and phosphoric acid in soft drinks, WebMd settles on caffeine. "Caffeine leaches calcium from bones, sapping their strength." Darn!

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I love the caffeine buzz. Still, I have osteoporosis. WebMd quotes Linda K. Massey, a professor of human nutrition at Washington State, who says it's OK if you limit caffeine to 300 milligrams daily, which means one 16-ounce cup of coffee (320 mg).

But a related WebMd article, "Caffeine Shockers," shows the challenge of staying with the limits by noting that caffeine is found in energy drinks, sodas and "even gum," as well as coffee-flavored frozen yogurt and ice cream and some medications — 56 to 120 milligrams for a standard dose of over-the-counter pain relievers and up to 200 milligrams in weight control aids.

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"But [other] products with surprisingly high caffeine content … [such as] energy and coffee drinks don't clearly list caffeine content on packaging," it adds.

As always, a moderate amount won't hurt you, but coffee's one of those fun foods. It's easy to get hooked on the high it creates or the congeniality accompanying caffeine-stoked conversation.

The American Journal of Clinical Nutrition agrees that "caffeine intake increases the rate of bone loss in elderly women and interacts with vitamin D receptor genotypes 1,2,3,4."

Caffeine's stealing my bones, just as I thought.

But hold on. Conflicting information popped up.

An American Journal of Epidemiology article looks at a Swedish study of "Long-term Coffee Consumption in Relation to Fracture Risk and Bone Mineral Density in Women." It looked at 61,433 women born between 1914 and 1948 who were followed from 1987 through 2008. Researchers found high coffee consumption associated with only a small reduction in bone density and that this did not translate into an increased risk of fracture.

So what's going on? Where is the straight scoop?

I depend upon WebMd's reliability, yet was impressed with the rigors of the journal's Swedish study and its final sentence, "This ends a long-running debate about coffee as a potential risk factor for osteoporotic fractures, at least in women."

The National Institutes of Health published a Korean Journal of Family Medicine article from 2014 about coffee consumption and osteoporosis risk that found that coffee consumption by premenopausal women showed "no bone loss to spine or femoral neck densities." However, this caveat is included: "To date, it is well known that consumption of coffee may increase urinary excretion of calcium, which may induce osteoporosis especially in people with inadequate calcium intake such as the elderly."

It ends with this advice to reduce risk of osteoporosis: Ensure adequate calcium and vitamin D intake and limit coffee consumption to up to three cups a day, particularly in older adults.

OK, what I gather is that, yeah, as a 72-year-old female, I may be excreting calcium, especially if I happen to have something called genotype 2, 3, and 4.

For most people, however, daily coffee won't hurt their bones if they get enough calcium and vitamin D, best from dietary sources but also from supplements. Seniors should show moderation in caffeine consumption, maybe a cup or two a day, with great care in eating a calcium-rich diet, supplementing with 1,000 international units (IU) of calcium and 400 of vitamin D.

I'll have tea next Sunday, reserving coffee for long, hot drowsy car drives and coffee dates with friends.

Remember Benjamin Franklin's often repeated dictum: moderation.

Newport Beach resident CARRIE LUGER SLAYBACK is a marathoner in her 70s who brought home first places in LA Marathons 2013 and 2014 and the Carlsbad Marathon 2015. She lives in Newport Beach.

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