Depending on who you ask, between one-half and two-thirds of Americans
take a dietary supplement at least once a week. According to data from
the 1999?2000 National Health and Nutrition Examination Survey
(http://aje.oupjournals.org/cgi/content/abstract/160/4/339), 52% of
adults took a dietary supplement in the month before the survey. That
number is somewhat smaller than most of the nonscientific numbers I
found (most estimated 60% to 70%).
According to a 2002 Harris survey discussed at
69% take supplements, and the median number of supplements is 30 per
30 days, or one per day. By definition, half of the survey group take
more than the median, and half take less. Assuming 34% of respondents
(what?s left after the 66% who take supplements) said they take no
pills, it?s a good bet that most supplement users take more than one
pill a day (data from the British Columbia study I cite below bears
that out). While college-educated respondents were more likely to be
skeptical of the health claims of supplements, they were more likely
to take the pills, and tended to take more of them.
However, I was only able to find one academic study that specifically
addressed U.S. pill consumption. According to a 1999 revision of a
1997 study by University of Wisconsin researchers, many Americans are
willing to take at least 10 pills a day.
This was a small study, with just 33 participants
(http://healthproductsusa.net/article13_health.htm). All were white.
Twenty-six (79%) had some college education. Seventeen (52%) were
either college graduates or had a postgraduate degree. All of the
participants took at least 2 dietary supplements, which suggests that
the survey wanted to limit itself to serious supplement users. As
such, these people are probably more likely than the general populace
to take a large number of pills. Twenty-four (73%) took more than 5
supplements per day, and 12 (36%) took more than 10 per day.
The more-detailed 1988-1994 National Health and Nutrition Examination
Survey contains the data you require, but the raw data is nearly
impossible to extract. However, a summary
available online. The data is taken from 1988 to 1994, the period in
which supplement use began to expand dramatically. As such, the
numbers certainly understate current supplement use.
But even during the period of this survey, 15% took more than three
supplements a day.
I know you want U.S. numbers, but I found a British Columbia survey
that should help you
According to this survey, 64% of respondents took supplements in the
last month, which is close to the results from the Harris survey.
Based on the margin of error for both surveys, the difference is not
According to the B.C. study, most users took one or two supplements
per day, but 25% took at least four per day.
Warning: Because nonusers are less likely to take a supplement survey
than users, the actual supplement penetration for North America is
probably lower than the Harris and British Columbia surveys indicate.
But the data regarding how many pills supplement users take is quite
Bottom line: While most Americans do not take four or more pills a
day, there is a significant minority that do. And the fact that 36% of
a study group of supplement users took 10 per day and 73% took five
per days suggest that many supplement users would be willing to take
five or 10 a day if they believed there was a compelling reason to do
Another interesting site:
This story discusses research about the growth of the
nutritional-supplement industry and contains such nuggets as 77% of
Americans think nutrition is more important than price, according to a
study by the Food Marketing Institute.
"number of pills" survey supplements