Medical myths: Vitamins and supplements
The supplement industry is huge. In 2016, the global nutritional supplement sector turned over an estimated $132.8 billion. By 2022, some experts predict that this figure will exceed $220 billion. But are they all that they are cracked up to be? In this edition of Medical Myths, we address a crop of supplement superstitions and misunderstandings.
When it comes to vitamins, more is not always better
In fact, more can sometimes be dangerous
- For adults without health conditions who eat a balanced diet, the vast majority of supplements are nonessential
- However, taking too much vitamin D over long periods can cause calcium to build up in the body, which is called hypercalcemia
- This can weaken bones and damage kidneys
Oxidation is a chemical reaction that occurs as part of many processes in the human body.
Antioxidants are compounds that prevent oxidation, and they include vitamin C, vitamin E, selenium, and carotenoids
- Several studies have looked at whether antioxidant supplements can help prevent chronic diseases, including cancer, cardiovascular diseases, and cataracts, but in most instances, antioxidants did not reduce the risks of developing these diseases.
The term “natural” is meaningless in relation to the safety or effectiveness of a supplement
Some natural plant compounds do have medicinal properties, but there is more to it than that
There is still no consensus on whether vitamin D has a beneficial anticancer effect
A large meta-analysis published in 2019 concluded that, although vitamin D did not reduce the incidence of cancer, it did reduce cancer mortality.
- Although vitamin D supplementation was not linked with decreased cancer incidence, it was associated with a reduced incidence of advanced cancer.
Many claim that supplements do not interact with prescribed medication, but in reality, many of these products contain active ingredients that might interfere with other drugs.
In a 2012 review, researchers investigated “drug interactions and contraindications associated with herbs and dietary supplements.”
- Supplement containing magnesium, St. John’s wort, iron, calcium, and ginkgo had the greatest number of interactions
Probiotics and Prebiotics
Probiotics are foods or supplements that contain microorganisms (microorganisms) that promote gut bacteria; prebiotics are compounds designed to promote bacteria
- The science of the microbiome is still relatively young, but it is already implicated in conditions as disparate as hypertension, diabetes, and depression
- Outside of a few specific conditions, there is little evidence that probiotics or pre-biotics can benefit health outside of diarrhea and irritable bowel syndrome
- Currently, it is marketing that drives the sale of probiotics and prebiiotics, using vague terms like “gut health” and “digestive health”
A large review and meta-analysis published in 2018 could find no significant benefit.
Overall, the authors conclude: “In general, the data on the popular supplements (multivitamins, vitamin D, calcium, and vitamin C) show no consistent benefit for the prevention of [cardiovascular disease, myocardial infarction, or stroke], nor was there a benefit for all-cause mortality to support their continued use.”
2013 Cochrane review
The authors’ objective was to “find out whether vitamin C reduces the incidence, the duration, or severity of the common cold when used either as a continuous regular supplementation every day or as a therapy at the onset of cold symptoms.”
- They found that vitamin C supplementation did not prevent colds.
- However, they did conclude that it reduced the severity of symptoms and the duration of the cold.
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