To Calcium or Not to Calcium?

Two big studies that came out recently have muddied the waters on the one nutritional supplement that even conventional medicine has rallied behind:  calcium.

We've all heard that supplemental calcium is good for the bones, and may even protect against colon cancer in older adults.  Seems like a logical recommendation.  But like hormone replacement therapy, whose cardiovascular benefits were disproven ten years ago by the Women's Health Initiative study, calcium supplements are now being called into question.

The first chink in the armor came a few weeks ago when a study sponsored by the National Institutes of Health (NIH) (1) found that supplemental calcium boosts the risk of death by cardiovascular disease (CVD) in men, but not women.  Men who consumed 1000 mg/day of calcium supplement had a 20% higher risk of CVD death than those who took no calcium.

OK, great... men, ditch the calcium; women, keep popping those ginormous horse pills.  Until February 13, when BMJ (British Medical Journal) (2) published the findings of Swedish scientists, who found that calcium supplements increased death rates in women, too.  Examining the findings more closely, though, we find some important details:  the all-cause mortality rates were doubled in women with a calcium intake of  more than 1400 mg/day, compared to those getting 600-1000 mg/day.  A further complication is that risk of death was increased if the calcium came from supplements rather than food.

The US Preventive Services Task Force (3) has also chimed in, with a re-analysis of older data that showed that 400 IU of vitamin D plus 1000 mg of calcium per day did not significantly prevent fractures in healthy older women.

These studies add more weight to hints that have been accumulating over the years, that just increasing calcium intake is not necessarily better for health.  Some cultures of the world have very low levels of calcium intake, but very little osteoporosis.  Meanwhile, the US recommendations for daily calcium have climbed over the years, so that now the RDA for women over age 50 is 1200 mg/day.  When it comes to bone health, just adding more calcium is like throwing more bricks on a construction site, and hoping that they'll form a building.  You also need an architect and foreman -- namely, vitamin D and vitamin K.

So how do we parse all this confusion about calcium, health, and disease for older adults?  Here's my bottom line:

• Men:  Keep your daily calcium intake under 1000 mg/day.  For most men, this means skipping the calcium supplements altogether.
• Women:  Ditch the high-dose calcium supplements that provide 1000-1500 mg/day.  Aim for that 600-1000 mg/day range total between dietary and supplemental calcium, with an emphasis on dietary sources (dairy, leafy greens, sardines).
• Men and women:  Get your blood tested for 25-hydroxyvitamin D on a regular basis; aim for a level between 40-80 ng/ml.  If it is low, you may safely take higher levels of supplemental vitamin D3 (consult your doctor for the right amount -- I usually recommend anywhere from 2,000-10,000 IU per day).  If you have CVD, osteoporosis, or risk factors for these conditions, be sure to get extra vitamin K along with vitamin D3.

Stay tuned; like all of nutritional science, the landscape and recommendations are constantly in flux.

1.  Xiao Q, Murphy RA, Houston DK, Harris TB, Chow WH, Park Y. Dietary and supplemental calcium intake and cardiovascular disease mortality. JAMA Intern Med 2013; DOI:10.1001/jamainternmed.2013.3283. 

2.  Long term calcium intake and rates of all cause and cardiovascular mortality: community based prospective longitudinal cohort study.  BMJ 2013; 346 doi: http://dx.doi.org/10.1136/bmj.f228 (Published 13 February 2013)

3.  

Vitamin D and Calcium Supplementation to Prevent Fractures in Adults: U.S. Preventive Services Task Force Recommendation Statement.  Ann Intern Med. 26 February 2013

Another Nail in the Coffin for Diet Soda

All right, Dr. Peters, will you lay off the diet-soda-bashing melodrama?

No.  The answer is no.

You've read my articles before about how diet soda actually promotes weight gain rather than weight loss, and more seriously, raises the risk of stroke significantly.  Is that Diet Coke fix worth a brain attack that could lead to permanent neurologic deficit, or even death?

Now French researchers have published findings (1) that consumption of lots of diet soda more than doubles the risk of developing type 2 diabetes, compared to non-soda drinkers.  This is an even higher risk than regular soda drinkers!  As you know, type 2 diabetes is like aging on fast forward, accelerating the development of cardiovascular disease, nerve problems, kidney disease, eye problems, and other complications.  But wait -- how much is "a lot" of diet soda?  More than about 600 ml per week.  Or for us Americans, about 20 fluid ounces.  Yes, just one 20 oz. bottle per week.  Know anyone who drinks more pop than that?

So let's look at the arguments of the beverage industry:

• "Diet soda is a good choice for those trying to lose weight, since it contains zero calories."  FALSE
• "Diet soda is a good choice for diabetics, since it contains no sugar."  FALSE

Consider the alternatives:

• Get a reusable water bottle, and make pure water your go-to drink.  Add a squirt of real lemon or lime juice for a little flavor, if you miss it.  No need to replace one highly processed food (diet soda) with another ("designer" waters).
• Green tea:  go beyond the Lipton -- there are many different varieties, with flavors that should appeal to everyone.  And how about a 20-30% lower risk of cardiovascular disease as a bonus?

1.  Consumption of artificially and sugar-sweetened beverages and incident type 2 diabetes in the Etude Epidémiologique auprès des femmes de la Mutuelle Générale de l'Education Nationale–European Prospective Investigation into Cancer and Nutrition cohort.  January 30, 2013, doi: 10.3945/​ajcn.112.050997.  Am J Clin Nutr March 2013 ajcn.050997

What's Wrong with a Little Snack?

...Nothing, as long as it does not turn into a big snack.

One of the major factors that has been consistently found to influence weight gain or loss is controlling portion size.  Sometimes this is easier said than done -- for example, at buffets where the available portions are seemingly endless.

Researchers at Cornell University (1) recently ran an experiment to test this in a new way.  They gave two groups of people different serving sizes of snack foods (chocolate, pie, and potato chips) -- either small or large portions.  Of course, the choice of foods was not ideal (unless you count the health benefits recently coming to light for chocolate), but the point of the study was to look at calorie intake.  Not surprisingly, the small serving group took in fewer calories -- an average of 100 fewer.  What was important, though, is that they found no difference in reported satisfaction between the two groups.

This highlights a major principle of our food consumption:  the difference between hunger and appetite.  Hunger is the physiological need for food, detected and driven by the hypothalamus in the brain.  Appetite is the psychological desire for food, which can be the result of numerous factors -- one of which might be how much we have available in front of us.

So if you're going to have a snack, remember these principles:

• Measure out a small serving of snack ahead of time.  Don't grab the whole bag.
• Eat slowly -- give your brain a chance to catch on to that feeling of a satisfied appetite before reaching for more.

1.  Van Kleef, Ellen, Mitsuru Shimizu and Brian Wansink (2013). Just a bite: Considerably smaller snack portions satisfy delayed hunger and craving, Food Quality and Preference, 27(1):96-100