I’m a Dietitian — Here’s How I Actually Think About Supplements (and What I Tell My Clients)

If you’ve ever stood in the supplement aisle or scrolled online wondering where to even start, you’re not alone. I hear this from clients all the time: Do I actually need to take a supplement? And if so, which ones are worth it? The truth is, supplements can be helpful, but they’re not a substitute for a solid nutritional foundation, and not everyone needs them.

As a registered dietitian, I think about supplements a little differently than what you’ll often see on social media. People often ask, “What should I take?” I prefer to start with “What might be missing from your diet, or what has evidence to support it for this specific goal?” These are the questions we want to help you answer with this guide.

In this article I combine my experience with input from other dietitians, physicians, and current research to break down eight of the most common supplement categories, what they actually do, and who may benefit from them. My goal is to help you feel more confident in making supplement decisions that fit your needs.

Because needs can vary so much, I encourage clients to check their levels first. “Supplementation can be helpful, but ideally it’s based on blood levels,” says registered dietitian Samantha DeVito, MS, RD, CDN. This helps ensure you’re taking an appropriate amount for your needs — not just guessing.

That said, fiber supplements can be a helpful tool in certain situations. If you’re struggling to meet your needs, adding a supplement may help fill the gap.

Calcium plays an important role in building and maintaining bone structure throughout life.

It’s helpful to look at both your diet and lifestyle first, then consider supplementation if you’re at a higher risk of low intake or have increased bone needs.

Multivitamins are often the first supplement people reach for, and in some cases they can be a helpful safety net. “A multivitamin provides a combination of essential vitamins and minerals that help fill potential nutrient gaps, supporting overall health, energy metabolism, immune function, and bone health,” says Brownstein.

That said, multivitamins aren’t a replacement for food, and more isn’t necessarily better. “I recommend choosing a multivitamin that provides around 100-percent or less of daily needs. More is not better,” says Zuniga.

Multivitamins can be especially useful during certain life stages, during illness, or if you take medications like GLP-1s that affect how much you eat. But the goal is still to get as many nutrients as possible from food first.

There are also clear situations where supplements can be beneficial. Certain life stages and circumstances, such as pregnancy, aging, restrictive diets, or conditions that affect nutrient absorption, may increase nutrient needs. 

Overall, supplements are best approached as a targeted tool rather than a blanket recommendation. “I often tell my patients to only take supplements that their body needs,” says Oparaji.

The FDA does monitor supplements once they’re on the market and can take action if safety concerns arise, but this often happens after issues are reported, creating what Zuniga describes as a “buyer beware” market, where companies are responsible for ensuring their products are safe and accurately labeled.

Because quality can vary widely, I always look for third-party testing when recommending supplements to my clients or when using them myself or for my family. This helps verify that what’s on the label is actually in the product.

Choosing a supplement can feel overwhelming, but there are a few things to consider:

• Look for third-party testing: This is one of the first things I look for to help verify purity, potency, and the absence of contaminants. Certifications like NSF or USP are voluntary but add an extra layer of quality control. “This means the product has been independently tested to verify that it contains what the label states and does not contain harmful contaminants or impurities,” says Zuniga.
• Stick with simple ingredient lists: “More isn’t always better when it comes to some nutrients,” says Devito. I agree and typically look for supplements with minimal added ingredients and doses close to recommended daily needs unless there’s an obvious need for more.
• Check for transparency: “I also recommend prioritizing brands that are transparent about sourcing and manufacturing (GMP-certified facilities),” says Oparaji. While not all brands offer this extra layer, it’s helpful to choose brands that are transparent about sourcing and manufacturing practices.
• Avoid unnecessary add-ons: Blends with added herbs, enzymes, or proprietary ingredients aren’t always necessary and can make it harder to know exactly what you’re getting.

Supplements can be helpful, but they’re not risk-free. “Many assume that because supplements are OTC and easy to purchase that they are safe, but supplements should be approached with the same level of caution as medications,” says Zuniga.

Overall, supplements are a useful tool, but you want to make sure they are of high quality. They work best when targeted for your needs and used with guidance rather than guesswork.