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A Doctor’s 4 Step Guide to Assessing Ingredient Quality in Supplements

By Venus Ramos, MD

In this article:


The dietary supplement industry is massive, with well over 50,000 products on the market in the United States alone. With the myriad of products available, it can be difficult to sort through them all, separate credible information from the unreliable, and make the right supplement choices for you. Here are some things to consider when assessing the quality of a supplement.

‌‌‌‌1. Verify That the Product Has Been Tested By a Third-Party Lab

Drugs are regulated by the U.S. Food and Drug Administration (FDA), but supplements are not. In 1994, the Dietary Supplement Health and Education Act (DSHEA) strictly limited the FDA's power to regulate any products marketed as "dietary supplements." Consequently, supplement manufacturers can sell their products without providing any evidence of their safety, purity, potency, or efficacy.

So, if you want to know that a product actually contains the ingredients on the label, does not have any contaminants, and has been manufactured using acceptable practices, then you’ll want to make sure that it has been tested by a third-party organization.

Look for a certification mark indicating that a product has been tested and certified by an independent organization like the United States Pharmacopeia (USP) Convention, National Sanitation Foundation (NSF) International, and ConsumerLab.com.

‌‌‌‌2. Check for Scientific Evidence That Supports Health Claims

According to law (DSHEA), supplement companies are prohibited from claiming that their products cure, treat, prevent, or diagnose diseases. That is why you’ll often find product labels with a disclaimer such as "This statement has not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease." However, manufacturers are allowed to claim that a product affects the body’s nutritional status, function or structure, or general health and well-being.

While it may take some time and effort on your part, find out if there are research studies to back any claims of a product’s effect on your health. The manufacturer’s website may have links or citations for journal articles. If a company is making a bold claim about its product without any supporting research, then you should be cautious about choosing it.

There are two main types of studies you may come across–observational studies and randomized controlled trials. When investigating a supplement, researchers generally start with a simple observational study, comparing the health of those who take a certain supplement with the health of people who do not take it. The results of such a study, however, do not always provide enough proof that the supplement caused a certain effect.

Researchers can get better evidence from conducting randomized controlled trials. In these studies, participants are arbitrarily assigned to take either the supplement or a placebo (which is an inactive substance that looks identical to the supplement being researched). The best evidence comes from such studies when they are double-blind, meaning that neither the participants nor the researchers know who is getting what–the real supplement or the fake one–until the trials have ended.

It’s also good to take note of whether a study is performed on animals or humans. Of course, when it comes to the safety and effectiveness of a supplement, you want to see that it’s been studied in humans.

‌‌‌‌3. Opt for Natural Ingredients

It’s best to meet your body’s nutritional requirements by consuming natural whole food forms and, whenever possible, going with organic. However, it can certainly be hard to keep track of everything you’re eating and get all the nutrients in all the necessary amounts through whole foods alone.

So taking a supplement can be a wise decision when you want to make sure that you’re getting all the nutrients your body needs. That’s why many people start with multivitamins as their introduction to a daily supplement regimen.

When choosing daily supplements, look for pure products with no added colors, sugars, or artificial flavors. Avoid any ingredients that have been genetically modified. Genetically Modified Organism (GMO) is the term commonly used to describe food products that have been created through genetic engineering.

GMO products are generally not good for your health or for the environment. Toxic pesticides and herbicides are often used in the production of GMO crops. Glyphosate is the active ingredient in many herbicides, and it has been associated with health conditions such as cancer, digestive issues, and liver and kidney problems.

‌‌‌‌4. Know The Pros And Cons Of The Various Delivery Forms

Tablets, in general, are the most cost-effective supplements because they allow the manufacturer to pack the most material into a given space. Essentially, this gives you the ability to get higher potency for a lower price compared to other forms. Tablets tend to have a longer shelf life, retaining their potency over a longer period of time (often 2-3 years). Tablets come in a wide variety of shapes and sizes.

Some people may have difficulty swallowing large tablets. However, they can be crushed prior to consumption. Dosing options are not as flexible as what liquids and powders offer. Some examples of supplements you’ll typically find in tablet form are zincmagnesium, and biotin.


Capsules are one of the most common forms of supplements because they are easy-to-swallow and break down quickly in the stomach.

The actual supplement is enclosed in an outer shell made from two interlocking pieces of gelatin (a meat byproduct) or a vegetable-based alternative. The shell tends to be tasteless, so you can avoid the bad taste associated with some tablets.

Some capsules can be taken apart, which gives you the option of consuming all or part of its powdered contents. This can be useful in the case of a child or someone who cannot swallow pills because you can mix the contents in something like applesauce or a protein powder smoothie. Of course, when you open up a capsule, you lose the benefit of tastelessness.

Capsules tend to be higher priced compared to tablets. Since the contents of capsules cannot be significantly compressed, there are limitations on space and potency. So you may need to take more capsules to get the same dose that you would with tablets.

Because capsules are less durable and are not air-tight, they are not as stable as tablets. Capsules may be affected by environmental conditions like humidity. Their shelf-life is shorter compared to other forms. Some examples of supplements you’ll typically find in capsule form are vitamin Dvitamin B complex, and L-tyrosine.


Softgels are similar to capsules. However, the outer shell is a layer of a soft substance and it encloses a liquid or oil-based supplement formula. There are vegetarian softgels available, but a gelatin shell is the most common type on the market.

Given their smooth contour and flexible shape, softgels are easy to swallow regardless of size. Because they are completely sealed, they generally offer a longer shelf-life than liquids, capsules, and powders, although this may depend on the actual contents.

Softgels require fairly specialized manufacturing, so they can cost much more than tablets or capsules. They must also be carefully stored as they are susceptible to hot weather. Some examples of supplements you’ll typically find in softgel form are omega 3slecithin, and CoQ10.

Chewables are tablets that are meant to be chewed and then swallowed rather than be swallowed whole. Advantages include ease of swallow, the stability of a tablet form, and no need for water to consume.

Because they are designed for chewing, taste is an important factor. So they often contain sugar or flavors that a health-conscious person might want to avoid. Compared to tablet and capsule forms, they also tend to be higher in cost and lower in potency. Some examples of supplements you’ll typically find in chewable form are children’s multivitaminsmelatonin, and calcium.

Gummies are another chewable supplement alternative. They may be helpful if you have difficulty swallowing or want to avoid the bad taste of certain tablet options. Remember that in order to improve the taste, sugars and flavors are often added which may make gummies less of a healthy choice. Because taste is prioritized, there is also a risk that gummies may be eaten like candy and excess amounts could be consumed. Since many children’s supplements are in gummy form, it’s important to take proper care.

There is some research showing that the average doses of vitamins in gummy format are often higher than the recommended amounts. Gummies are not as stable as tablets and because degradation can occur, manufacturers may be adding a higher concentration of vitamins to account for this anticipated loss of potency. Furthermore, certain nutrients included in pill forms are omitted in gummy vitamins due to flavor concerns. For example, iron is usually not included in gummy vitamins because of its metallic taste.


Powders offer a convenient form for supplements that require large servings of nutrients, like protein. There is great flexibility with dosing and you can combine several supplements at one time. 

Powdered supplements have a long shelf-life and can be very cost-effective. They do, of course, require mixing in liquid (i.e. water, juice, or blended food).


Liquid supplements can be a good option for those who cannot or do not want to swallow pills. Many prefer liquids based on their belief that they absorb more quickly than other forms. But research is inconclusive about whether this faster absorption amounts to a significant nutritional difference for your body.

In fact, slower absorption may be more desirable when you’re dealing with higher potencies. There is a limit to how fast any nutrient can be absorbed. When highly potent substances are delivered quickly, the absorption process can be overwhelmed and nutrients end up being wasted. There are, however, situations where faster absorption serves the supplement’s intended effect. Such is the case with many pre-workout supplements or energy products.


Liquid supplements almost always have a higher price tag and shorter shelf-life than other forms. Many contain sugar and other flavors that you may want to avoid. They are also less portable than pills and often need to be refrigerated. 

References:

  1. Elliott C. Assessing Vitamins, Minerals and Supplements Marketed to Children in Canada. Int J Environ Res Public Health. 2019;16(22):4326. Published 2019 Nov 6.

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