According to a nutritionist, this is the biggest red flag in a multivitamin.

What constitutes a "excellent" multivitamin? Don't worry, we've already verified a list of 18 best options, but as you peruse, it's always a good idea to familiarize yourself with your supplement facts panel. There's a lot of marketing lingo to decipher, and some labels are a little dubious.

Ashley Jordan Ferira, Ph.D., RDN, our in-house nutritionist and director of scientific affairs, recognizes one word in particular that gives her pause. She explains the No. 1 red flag to look for in a multivitamin in this article.

The biggest warning sign when it comes to multivitamins.

The FDA does not regulate the supplement market, contrary to popular belief. This isn't accurate at all.

Any supplement brand that employs the word "pharmaceutical-grade" to describe its components, according to Ferira, is suspect. There's a common misconception that the supplement market is uncontrolled by the FDA. This is completely untrue. In terms of what claims are legally allowed on supplement labels, the FDA has very strict requirements (a breakdown of those rules may be seen here): Foods are distinct from dietary supplements, which are distinct from over-the-counter (OTC) medications, which are distinct from prescription pharmaceutical drugs, within these borders.Each category has its own lane, with procedures to follow and claims to make—so when medicinal terminology finds its way into dietary supplements (like a multi), it's crossing into another lane without a figurative blinker, and that's just plain dangerous in driving and elsewhere.

Words like pharmacist-recommended, doctor-formulated, guaranteed quality, thorough, and complete may also appear, but they may have no meaning (unless those claims have verifiable backing). High potency, on the other hand, is a controlled nutritional content claim, as defined by the FDA in 1997. This means that at least two-thirds (or 67%) of the components in multi-ingredient supplements must have a daily value of 100% or higher (DV).

On the mindbodygreen podcast, Ferira remarks, "That is blurring a boundary." "And the laws in the United States have clearly delineated lines." "I would say that's a red flag," she continues. "I'd just go on, just like in a romance."

You may also come across words like pharmacist-recommended, doctor-formulated, guaranteed quality, thorough, and complete, all of which may have little meaning (unless those claims have verifiable backing). High potency, on the other hand, is a nutritional content claim with a controlled definition, as stated by the FDA in 1997. This means that at least two-thirds (or 67 percent) of the components in multi-ingredient supplements must have 100% or more of their daily value (DV).

"That is blurring a border," Ferira says on the mindbodygreen podcast. "And in the United States, the laws have clearly defined lines." "That, to me, is a red flag," she continues. "Like in a romance, I'd just keep going."

So, if your supplement claims to be high-potency, review the ingredient list to make sure the claims are true. If you're curious, mindbodygreen's ultimate multivitamin+ comes in at well over two-thirds of the way; in fact, the multi can claim a staggering 83 percent of its vitamins and minerals as high potency DVs (which is well above the 67 percent requirement). "If you look at the product and turn it over, the supplement facts panel makes it extremely evident," Ferira explains.

The Bottom line.

When picking a multivitamin (or any other supplement for that matter), it's crucial to distinguish between what's a legitimate nutritional promise and what's just marketing fluff. After you've eliminated the underperformers, you'll be able to select the optimal formula for your nutritional goals and lifestyle that checks all of the boxes.Consult your doctor before beginning a supplement regimen if you are pregnant, breastfeeding, or using medications. When deciding which supplements are ideal for you, it's always best to consult with a health care expert.