Supplement Red Flags: What Dietitians Should Watch For

The dietary supplement industry generates over $60 billion annually in the United States alone. It is also one of the most loosely regulated consumer product categories. Under the Dietary Supplement Health and Education Act (DSHEA) of 1994, supplements do not require FDA approval before going to market. Manufacturers are responsible for their own safety testing.

For sports dietitians, this creates a challenging landscape. Athletes are bombarded with supplement marketing, and the consequences of a contaminated product — a failed drug test, a health crisis — can end a career.

Red Flag 1: Proprietary Blends

A “proprietary blend” lists ingredients without disclosing individual doses. The label might read “Performance Matrix: 5g (beta-alanine, creatine, L-citrulline, caffeine)” without specifying how much of each ingredient is included.

This is a problem because:

Effective doses are well-established for most ingredients (e.g., 3-5g creatine, 3.2-6.4g beta-alanine)
A proprietary blend may contain sub-therapeutic doses of expensive ingredients and fill the rest with cheap fillers
Without knowing the caffeine dose, members risk exceeding safe limits or failing anti-doping thresholds

Rule: If the label does not disclose individual ingredient amounts, do not recommend it.

Red Flag 2: Claims That Sound Too Good

The FDA prohibits supplement manufacturers from claiming their products diagnose, treat, cure, or prevent any disease. However, “structure/function” claims are allowed — and companies push these boundaries aggressively.

Watch for:

“Clinically proven” without a citation to a peer-reviewed study
Dramatic before/after photos (not evidence)
Testimonials from professional members (paid endorsements, not clinical evidence)
“Pharmaceutical grade” (this term has no legal definition for supplements)

Red Flag 3: No Third-Party Testing

Third-party certification programs test supplements for banned substances, heavy metals, and label accuracy. The major programs include:

NSF Certified for Sport: The gold standard for collegiate and professional members. Tests for over 290 banned substances.
Informed Sport: Widely recognized internationally. Tests every batch.
USP Verified: Primarily for general supplements (not sport-specific), but indicates quality manufacturing.

If a supplement does not carry one of these certifications, there is no independent verification that the label is accurate or that the product is free from banned substances.

For NCAA, NFL, NBA, and Olympic members: Recommend only NSF Certified for Sport or Informed Sport products. The risk of a contaminated supplement is not hypothetical — studies have found that 12-25% of supplements available in the U.S. contain undeclared substances.

Red Flag 4: Ingredients You Cannot Pronounce or Verify

Novel ingredients appear in supplements constantly. Many have no human safety data, no dosing guidelines, and no long-term research. Some are renamed versions of previously banned substances.

If you encounter an ingredient that does not appear in the ISSN position stands or the Australian Institute of Sport supplement classification system, treat it with extreme caution.

Red Flag 5: Unrealistic Dosing

Some supplements contain doses that are either too low to be effective (pixie-dusting) or dangerously high. Examples:

Caffeine: Products containing 400+ mg per serving approach or exceed the safe single-dose limit
Vitamin D: Mega-doses (10,000+ IU/day) without medical supervision can cause toxicity
Iron: Over-the-counter iron supplements taken without confirmed deficiency can cause GI distress and iron overload

What Dietitians Should Do

Maintain a short list of vetted, third-party tested supplements you are comfortable recommending
Educate members on how to read supplement labels and recognize red flags
Audit current supplement use during intake assessments — members are often taking products they found on Instagram without telling anyone
Document recommendations in clinical notes for liability protection

The supplement conversation is a core competency for sports dietitians. If you are not having it, someone else — a strength coach, a teammate, an influencer — is filling that void with unvetted information.

For dietitians managing supplement protocols, Calsanova’s clinical notes and member management tools provide a structured way to document recommendations and track compliance.

Transparent dosing. Zero proprietary blends. Scythene Supplements — every ingredient disclosed at the clinical dose, third-party tested, built by the RD behind Combat Dietitian. The opposite of everything in this article. Code MPS20 for 20% off. Shop Scythene →