Supplements: Effectiveness, Use, and Safety

by Rob Siabanis MS, RDNLifestyle
Bottles with different colored pills spilling out


The supplement industry is booming in the US and is expected to grow to a market worth of $60 billion by 2025. This is partly due to increasing consumer interest in “immune-boosting” nutrients to combat COVID-related concerns. Most consumers are unaware that the supplement industry lacks the regulation and frequent inspection other industries undergo, such as the retail food service and pharmaceutical industries. This has resulted in a growing concern by healthcare professionals and educated consumers who point out the potential health hazards of manufacturing malpractice, be it intentional or not (1). This article will explore the effectiveness of supplements, the need for supplements, the safety of supplements, and conclude with ways to get the most out of taking them.

Do supplements work?

Perhaps the first question that comes to mind when one is interested in purchasing a product is whether it works. Even though dietary supplements have been around for centuries, there still appears to be considerable debate over the effectiveness of supplementation. One side argues that because supplements are unnaturally isolated food compounds, they cannot be utilized by the body effectively, some even going to the extent of saying that they give us “expensive urine” (2,3). On the other side, proponents treat vitamins as necessary as food and a requirement for health and wellness. The internet is awash with self-proclaimed health gurus promoting complex and ludicrously expensive supplement regimens that often include upwards of 30 pills per day. Is there any truth to either side?

The problem with these two arguments is that they are absolute. Supplements work, or they don’t. Truth is rarely that simple. Supplements have been shown countless times to help those with diagnosed deficiencies recover. For example, individuals with a B12 deficiency will return to normal health after supplementing with B12 (4). Similarly, those experiencing the debilitating symptoms of vitamin D deficiency (e.g., fatigue, impaired mood) will find relief after supplementing for a few weeks (5). 

The most powerful argument for the effectiveness of supplements is the nationwide fortification of food in the US food supply. In the 1920s and 1930s, diseases related to nutritional deficiencies were rampant. These diseases were almost eliminated after the 1940s, when food fortification programs were enacted in the US (6). Essentially, food manufacturers started adding multivitamins to our food to prevent nationwide nutrition-related diseases, such as goiter (iodine), rickets (vitamin D, calcium), beriberi (vitamin B1), and pellagra (vitamin B3). Therefore, the question is less about whether supplements work but more about who needs to take them. 

Who needs to take supplements?

The simple answer to this question is that those who are not getting enough of a particular nutrient through their diet or lifestyle may need to supplement. A classic example is vitamin B12 supplementation for those who avoid animal products and B12-fortified foods (e.g., dairy alternatives, nutritional yeast). Similarly, individuals who live in the northern hemisphere and get minimal sun exposure may require vitamin D supplementation (5). 

Another situation where supplementation may be necessary is when there is chronically poor absorption of certain nutrients (malabsorption) due to conditions such as cystic fibrosis, Celiac disease, and chronic pancreatitis. On a similar note, some medications limit the absorption of various nutrients and can result in nutrient deficiencies if taken for long periods. For instance, those who take antacids frequently risk multiple deficiencies, such as iron, B12, and magnesium (7).

One of the challenges when gauging the need to supplement is that some nutrients are notoriously challenging to measure accurately. Magnesium, for example, will rarely fall below the normal range in the blood because if the levels dip, more is released into the bloodstream from the areas it is stored (e.g., bones, soft tissue, muscles). Therefore, one might be getting inadequate or sub-optimal magnesium from their diet for months, but it won’t appear on the lab report because the “magnesium banks” are being emptied into the blood, thus masking the issue (8). Other essential minerals, such as zinc, operate similarly. This is why assessing nutrient intake with the help of a registered dietitian (RD) is a great way to mitigate this issue. Suppose the nutrient analysis shows that the patient is simply not getting enough of a particular nutrient. In that case, there is no need to wait until the blood levels get critically low before taking corrective action. 

Are supplements safe?

The main issue regarding supplement safety in the US is the lack of regulation. For there to be a thorough investigation by the Food and Drug Administration (FDA), there first needs to be “adequate reason,” usually in the form of customer complaints and reports to the Federal Trade Commission (FTC). In 2007, the FDA issued Current Good Manufacturing Practice (CGMP) guidelines and required supplement manufacturers to follow them (9). But when the FDA inspected a sample of supplement manufacturers in 2013 to assess compliance, 65% of the manufacturers did not meet these guidelines (10).

This apparent lack of oversight may partly explain the 50,000 annual cases of supplement-related complications in the US alone (11). One particularly harmful occurrence occurred in 2009 when consumers taking a dietary supplement experienced selenium poisoning due to manufacturer error. This could have been easily prevented with proper quality control (12). The FDA has investigated and identified hundreds of supplement products that were contaminated with heavy metals or had inaccurate labels on the bottles, which could lead to toxicity due to overconsumption of certain nutrients (1). The case of the memory supplement Prevagen was one such supplement horror story that received more attention than others (albeit, not enough attention).

The problem is not only that there are a few “bad apples” in the supplement industry but more so that the investigating bodies will step in only after the damage has been done (13). This is partly because the market is flooded with thousands of products each year, making a thorough third-party federal inspection exceedingly difficult (14,15). Therefore, most consumers that purchase supplements need to trust that the supplement companies are being truthful and are following good manufacturing guidelines. Unfortunately, the current track record and continuing lack of regulation and disciplinary action only cast doubt on the industry as a whole. Is there anything consumers can do to not fall prey to the industry’s faults and ploys? 

Tips for smart supplement shopping 

First and foremost, it is essential to determine whether you need to take a particular supplement. This is one of the reasons why consulting a registered dietitian (RD) is essential. A professional nutritional analysis of your dietary intake, health history, and present medication use will reveal the possible need for supplementation. This approach can also save you the effort and expense of buying more supplements than you actually need based on your present diet.

An RD can also educate you on how to take your supplements to get the most out of them. For example, did you know that drinking green tea after taking a supplement will significantly block the absorption of several minerals, effectively flushing them out of your system (16)? Or that vitamin D is best absorbed when taken with a meal, especially one with added fat (e.g., olive oil) (17)? Professional guidance will greatly improve the effectiveness of your supplements. 

Aside from seeking consultation from an RD, is there anything you can do on your own to sift through the thousands of products on the Internet? Absolutely. The main thing to look for in any supplement is a certification from a third-party organization. The three main ones in the US are ConsumerLab, NSF International, and USP. Final products undergo thorough testing for ingredient quality, quantity, purity, freshness, and condition (18). Because companies are not required to undergo certification, if a product has one or more of the above certifications on its packaging, it is an encouraging sign.

Additionally, companies such as Fullscript now offer an easier way to order high quality supplements at a more affordable price with the guidance of your healthcare practitioner.


Dietary supplements have repeatedly been shown to be beneficial when taken as needed. Even though the supplement market in the US is woefully under-regulated, there are ways for consumers to not only navigate it but also get the most out of their purchases so they can improve their health and wellbeing.


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