29th January 2010, Volume 123 Number 1308

Shaun Holt, Avrille Holt, Pieter Erasmus, Maryann Watson, Tony Farrell, Gareth Blackshaw, Mogens Poppe, Mike Williams, Andrew Gilbey

Over the last two decades there has been a trend for people to supplement their nutritional intake with dietary supplements (DS) (e.g. vitamins, minerals, botanical material and active ingredients derived from food or other biological material) bought from a variety of sources (e.g. pharmacists, health food stores, supermarkets, Internet).1

The largest recent survey in New Zealand, found that around 60% of adults had taken DS in the previous year.1 However, there is little information available on other factors associated with DS consumption in New Zealand, such as: how many DS people take; where they buy them; where they get advice; and how they decide what to take. We therefore undertook a survey to increase understanding regarding these questions.

A convenience sample of 265 adults waiting in five GP surgeries in the Bay of Plenty completed the survey during the period October to November, 2008. There were 215 females and 50 males; age groups were less than 21 years (n=8), 21–30 years (n=32), 31–40 years (n=53), 41–50 years (n=69), 51–60 years (n=48), 61–70 years (n=26), 71–80 years (n=13), over 80 years (n=8), and no response (n=8).

Responses indicated that supplements used (by at least 3% of respondents) included: Multivitamin (42%), Fish oil (32%), Calcium (16%), Vitamin B (9%), Folic acid (8%), Vitamin C (6%), Glucosamine (6%), Iron (6%), Magnesium (4%), Spirulina (3%). Overall, 61 different supplements were reported as being used.

Sixty-nine respondents (26%) reported taking no supplements, of whom 30 reported this was due to cost, 21 because they believed they did not help, 37 that they were not sure what to take and 5 that they already had a balanced diet (more than one response option was possible). Of the 196 respondents who reported having consumed supplements, the following sources were reported (more than one response option was possible): Pharmacist (50%), Health Food Store (45%), Supermarket (45%), Internet (4%), Doctor (3%). Regarding the frequency of DS consumption, 26% reported taking 1 per day, 20% took 2, 8% took 3, 7% took 4, and 6% took 5 or more per day.

With regard to whom respondents trusted for advice on supplements, 79% respondents reported they would trust their doctor, 61% their pharmacist, 56% advice from a health food store, 12% advice from the internet, 12% advice from television and/or from magazines

We also asked respondents how much they agreed with a series of statements designed to provide more information regarding their consumption of DS (Table 1).

View tables here.

To provide further understanding of respondents’ reasons for taking supplements, they were asked four questions that we hypothesized might reasonably influence people’s decisions to use supplements (Table 2). The most common reason appeared to be advice from a doctor and evidence of effectiveness.

The main findings of this survey were that 74% of adult respondents take at least one DS, the most common being a multivitamin followed by fish oil. Many responders felt that DS were important for maintaining good health but many also reported a large degree of confusion regarding what they should take.

The prevalence of DS use of 74% was somewhat higher than that found in other studies and may represent differences in survey questions. For example, New Zealand data collected in 1997 found a rate of 59% had taken DS in the previous year;whilst a USA survey from 1999 to 2004 found that 34% had taken a DS in the previous month.2

DS were bought approximately equally from three main sources: pharmacies, health food stores and supermarkets. Scientific proof of efficacy and doctor advice to be important, however, price was also an important consideration. Up to 25% of respondents expressed some concerns about which DS may be suitable and useful to use.

We acknowledge a limitation of this survey is that it was only conducted in one part of the country and thus our findings may not be representative of the prevalence and opinions of DS use in other areas of New Zealand in 2008.

In conclusion, our findings suggest that most adult New Zealanders take DS, but they also want better information on which ones work. Given the potentially adverse outcomes and waste of money associated with inappropriate use of some DS, and concerns expressed by some respondents, the means by which accurate and independent information regarding DS can be communicated to potential users would be welcomed.

Shaun Holt, Avrille Holt, Pieter Erasmus, Maryann Watson, Tony Farrell, Gareth Blackshaw
Tauranga

Mogens Poppe
Ohope

Mike Williams
Rotorua

Andrew Gilbey
Palmerston North

Author Information

Shaun Holt, Avrille Holt, Pieter Erasmus, Maryann Watson, Tony Farrell, Gareth Blackshaw, Tauranga, Mogens Poppe, Ohope, Mike Williams, Rotorua, Andrew Gilbey, Palmerston North

References

  1. Parnell WR, Wilson NC and Smith C. Dietary supplements: Prevalence of use in the New Zealand population. Nutrition & Dietetics 2006; 63(4):199–205.
  2. Millen AE, Dodd KW, Subar AF. Use of vitamin, mineral, nonvitamin, and nonmineral supplements in the United States: The 1987, 1992, and 2000 National Health Interview Survey results. J Am Diet Assoc. 2004;