Dietary Supplements Do Not Affect Lifespan


A large cohort study of an Icelandic elderly population suggests that use of dietary supplements does not lead to excess nutrient consumption, but is not linked to a longer lifespan.


Obtaining the proper amounts of various vitamins and micronutrients is an essential part of a healthy lifestyle. For the most part, all of these dietary requirements can be obtained from a balanced diet, but recently dietary supplements have become a popular resource for balancing dietary nutrition. Dietary supplements are especially recommended to elderly people as nutritional insufficiency is commonly seen in this age group. Supplements can go a long way towards building longer, healthier lifespans by protecting against health decline and disease caused by insufficient nutritional intake.Despite the added health benefits, use of dietary supplements increases the risk of exceeding the recommended doses for vitamins and nutrients. Previous studies reported contradicting evidence on the benefits of vitamin use; some showed evidence of improved health while others have observed a higher risk of mortality for multivitamin users compared with non-users.These reports raised safety concerns for long term multivitamin use. A study published in the British Journal of Nutrition looked at dietary supplement use in an Icelandic elderly population to identify how supplement intake contributes to the risks of exceeding recommended nutritional values, and to investigate whether supplement use is associated with mortality.

This study included5764 Reykjvik residents;58% female and 42% male with an average age of 77 at the beginning of the study. Prior to the study, scientists assessed the general health of all individuals in order to account for other factors that could influence mortality. Researchers recorded the educational status, smoking patterns, alcohol consumption, degree of physical activity, and other lifestyle characteristics that have an impact on human health. Participants filled out questionnaires explaining their dietary patterns and frequency of supplement use and submitted their supplements to a registry. To calculate the nutritional content obtained for each individual, scientists looked up the nutritional contents of each specified supplement in a database and multiplied nutritional content by the frequency of weekly use.

Results indicate that 77% of study participants used at least 1 dietary supplement.The most popular vitamin was fish-liver oil, used by 55% of the participants, followed by multivitamins, used by 31% of the participants. There were very few instances where vitamin and mineral consumption exceeded the recommended daily dose; the only notable exceptions were that 22% of the participants who used B6 supplements exceeded the recommended intake, as did 14% of participants who took Zn. Overall, patterns showed that vitamin users were less likely to smoke, were more educated, consumed less alcohol, and had a lower prevalence of diabetes than non-smokers. However, no correlation was found between dietary use and hypertension. Within a 7 year period, there was a total of 1221 deaths among the registered participants, but no significant correlation was identified between the use of vitamins and mortality rates.

This study provides interesting insight into the patterns of dietary supplement intake in an elderly population. However, it didn’t take into account the total nutritional value obtained from the regular diets of these individuals. Perhaps dietary supplements and nutritional content from food would actually increase the proportion of individuals whose nutrient dietary intake exceeds the recommended daily amount. Moreover, the study did not clearly state whether it only recorded the dietary supplements taken by people over the course of the study period, or whether it took into account lifelong supplement use. More studies will be needed to fully assess the benefits and dangers of dietary supplements.


Written By: Irina Sementchoukova, B.Sc