Nutritional Supplements for Diabetes Sold on the Internet

Business or Health Promotion?

Loredana Covolo; Michela Capelli; Elisabetta Ceretti; Donatella Feretti; Luigi Caimi; Umberto Gelatti


BMC Public Health. 2013;13(777) 

In This Article


This study provides an overview of NSs for the prevention and treatment of diabetes available on the internet, and focuses on the type of information provided by the websites as well as the scientific evidence supporting these products.

NSs have gained in popularity in recent years and their use by the population has increased considerably because they are readily available and are considered "natural" substances that can improve or prevent a number of conditions.[34] The internet, as both a source of information and a marketing tool, has contributed to the easy accessibility of these products.[11]

We analysed the content of 10 websites selling NSs for the treatment and prevention of diabetes, based on some of the NIH-ODS[13] and FDA indications.

In general, adequate medical information was lacking. Although NSs do not require FDA approval of their safety and efficacy, they are products offered to support people with diabetes and even mitigate the risk of disease-related complications in addition to prevent diabetes. For this reason, websites should take particular care when providing information. It should be noted that potential users, such as people with a chronic disease, already take drugs regularly. The risk of drug-NS interactions should not in fact be ruled out.[35,36] Only one website mentioned the possibility of side effects, and none mentioned possible interaction with drugs.

Additional concern could arise from the possibility of counterfeit products available on the Internet. NSs are less regulated than drugs and therefore more easily subject to counterfeiting.[37] As stated by FDA the manufacturer should be easily traced to guarantee transparency of the product.[3] It is interesting to note the manufacturer was clearly indicated in only three out of ten NS selected in this study but one of these one was not found in the list of manufacturers of the Dietary Supplements Labels Database.[38]

It should be emphasised that NSs are not a substitute for medical products, but only half of the websites stated this clearly, four via the FDA disclaimer and one in the FAQ section. It is interesting to note that when this was specified, the testimonials could be misleading. For instance, a company claimed in the FAQ section that the NS was not a drug substitute, although one customer reported: "…Today, his blood sugars are more stable… so much so that the doctor wants him to start weaning him off of his insulin…". Another company reported that the NS is a non-pharmaceutical product, without specifying that it is not intended to diagnose, cure, mitigate, treat, or prevent the disease. The testimonials in this website said such things as "Thank you so much for saving my eyes. I have not had any surgeries in a long time", or "My mom's advancing eye disease stopped, and slightly reversed, and her kidney improvement is amazing". One of the NSs considered in this study was cited in a warning letter by the FDA in 2006 because it was in violation of Federal Food, Drug and Cosmetic Act[39] regarding a claim that should not have been included on the website as a testimonial "…I had major problems with my feet, and always felt tingling and discomfort… Since using Insulate Plus this is a thing of the past…". This claim still remains, however.

It should be also noted that FDA states that a NS marker can make no health claims unless approved and that it is illegal to sell a NS and promote it on its label or in labelling as a treatment, prevention or cure for a specific disease or condition.[3] In our opinion some sentences retrieved in sales websites like "Helps you prevent and care diabetes" or "helps block diabetes complications" could be ambiguous.

These are many the reasons why it is necessary to consult a physician before taking a NS, but only five websites suggested contacting one, two of them only in the case of pregnancy, breastfeeding or suspected health problems.

This message should be presented clearly on the websites since it has been shown that only a small percentage of NS users (20–30%) inform their physician about supplement use.[34,40] Not informing their own physician, in addition to providing misleading information on the websites, could lead potential diabetic patients to stop taking conventional drugs, delay seeking adequate treatment as they are satisfied with their NS, or reduce adherence to conventional treatment.[41] Another point to consider is that potential users, such as patients with a chronic disease, could take these products for a long time. As far as we know, however, there is no information about the long-term effects of using NSs.

The risks for consumers regarding the misleading information provided by online companies selling heath related products direct to the consumer such as drugs[42] or genetic tests[43–45] are widely discussed by previous studies.

In the last years has been spreading the idea that people, in a view of a better prevention, need to be able to perform decision-making actions which are beneficial for the enhancement of their own health.[46] A recent study showed a great interest in complementary alternative medicine supplements in patients with diabetes as a strategy for active engagement in health and disease self-management.[47] It may be no coincidence that online companies often influence the formation of a positive attitude towards their products using the concept of empowerment. For instance sentences like "…helps you manage your diabetes…" or "keeping diabetes management affordable" found in some websites explain clearly this concept. However a misleading or not exhaustive information fails in making people empowered and a possible consequence is to lead people to a prevention not completely correct.

So it is also crucial that people acquire the ability to evaluate the information critically in order to be aware about their purchase and to use NS appropriately.

One of the NIH-ODS recommendations on how to evaluate health information on the internet[13] states that websites should provide medical and scientific evidence in support of the products presented. Testimonials by people claiming to have tried a particular product or service are not evidence-based and usually cannot be corroborated.

Only three websites provided scientific evidence supporting the NS offered. Few references actually concerned the effects on diabetes, however, and the majority of the articles were not recent (before 2002) (Table 2).

An analysis of literature in the last ten years about the most widely present ingredients found in NSs offered by the websites selected showed that scientific evidence is still lacking. There were RCTs and MAs or SRs for all but one of the ingredients selected, but the average number of subjects included in the majority of RCTs is 43 and the average number of studies included in MAs or SRs is 7. There is therefore a clear lack of large studies, particular RCTs, and the results are conflicting. These findings are in agreement with several studies seeking scientific evidence regarding NSs and diabetes[36,48] that emphasise that a real effect on diabetes management is not yet been established.

It is also interesting to note that the daily dosage of ingredients present in the NS, where indicated, was not very comparable to the dosage tested in the studies retrieved. In some cases the two dosages differed considerably, as in the case of Gymnema sylvestre, Camellia sinensis, biotin and Momordica charantia.

To our knowledge this is the first study focusing on NSs for the prevention and treatment of diabetes that are sold directly to the consumer on the internet. Concerns about the presence on the market of products of dubious efficacy are compounded with concerns about the misleading information – or lack of it – on the selling websites. Another point to underlined is the lack of a possible mediator, particularly a health professional, in the purchase of these products.

Some limitations of the study are the low number of websites retrieved and the fact that they are only in English. It is also reasonable to assume that this number will increase, as shown by data regarding use of the internet as a source of health information.[49] It is also interesting to note that a recent report[50] showed that 53% of American adults age 65 and over use the internet. This is the very age group affected by chronic disease. It was also shown that NS use is high among older people in UK.[51] In our opinion, the possible risks arising from this scenario that have been discussed in this study should not be ignored.

Another limitation of this study is that our evaluation of the scientific evidence in support of NSs only took into account one ingredient present in more than three products. It should be noted, however, that it is difficult to conduct research on NSs because product composition varies considerably from manufacturer to manufacturer, and different products have been studied. The ingredients are present in combination with other different ingredients in the NS and even the dosage varies greatly. It is therefore necessary to study the efficacy of NSs on diabetes, not the single ingredients, especially in the case of products claiming to reduce the risk of a disease or health-related condition, since potentially adverse effects and drug interactions cannot be entirely ruled out.