A recent ConsumerLab.com survey of more than 10,000 people who take dietary supplements shows that use of calcium, vitamin C and fish oil supplements fell during 2013 while use of probiotics increased. The decrease in calcium use was driven by a sharp decline in use by women (falling from 57.8 percent to 45.6 percent), while the decrease for vitamin C was driven by a decline in use by men (falling from 42.3 percent to 35 percent). Although still the most frequently purchased supplement, fish oil use declined by 4 to 5 percentage points among both men and women. The increase for probiotics was driven by a jump in the percentage of men using probiotics (rising from 30.5 percent to 37.1 percent), making this supplement now almost equally popular among men and women.

"The changes in supplement use seem to reflect research findings that made headlines this past year, as well as a shift in promotional emphasis for some of these supplements," said Tod Cooperman, M.D., president of ConsumerLab.com. "In the past, probiotics were marketed mainly to women and for irritable bowel syndrome, but are now finding a wider audience due to expanded treatment applications, including antibiotic-related diarrhea, diverticular disease and even anxiety. Meanwhile, too much calcium has been shown to pose increased risk of cardiovascular disease, while high-dose vitamin C appears to increase the risk of kidney stones and cataracts. The benefits of fish oil now seem largely limited to people who don't eat fish or have high triglycerides."

The results are based on responses to the most recent ConsumerLab.com Survey of Vitamin and Supplement Users, which has been conducted each November since 2008 among readers of ConsumerLab.com's e-newsletter. Respondents are predominantly heavy users of supplements who, on average, take 6.6 different supplements daily and actively seek information about these products.

The most popular supplements, based on the percentage of respondents who report using them in the recent study, are fish oil (including other marine oils, such as krill) (67.2 percent, down 4.5 percentage points from prior year), multivitamins (63.8 percent, down 1.6), CoQ10 (including ubiquinol) (54.1 percent, no change), vitamin D (53.8 percent, down 1.7), B vitamins (43.1 percent, down 1.1), calcium (42.1 percent, down 6.3), magnesium (38.1 percent, no change), probiotics (37.8 percent, up 3.4), and vitamin C (37.0 percent, down 4.2) followed by 23 other common supplements.

Respondents also identified where they purchase their supplements and rated 1,639 brands and 788 merchants they used. The supplement brands and merchants receiving the highest ratings on overall consumer satisfaction within their specific market segments are listed on the ConsumerLab.com website.

"We began the annual survey several years ago to direct our product testing toward supplement categories and brands of greatest interest to ConsumerLab.com members," said Dr. Cooperman. "It has evolved into an excellent barometer of the nutrition marketplace."