Multivitamins are among some of the most commonly used dietary supplements, in part because many people struggle to meet nutrient needs through diet alone. Limited access to nutrient-dense foods or dietary patterns low in fruits, vegetables, and whole grains (such as the standard American diet) may contribute to micronutrient deficiencies and significant health challenges over time. National Health and Nutrition Examination Survey (NHANES) data show that many Americans fall below the Estimated Average Requirement for several key nutrients, revealing widespread inadequacies in vitamins A, C, D, K, and E, as well as calcium, magnesium, and choline.

While multivitamins cannot replace a well-balanced diet, selecting an evidence-based formula may help support nutrient adequacy and fill nutritional gaps. Choosing a high-quality multivitamin, however, could feel overwhelming, given that the market is saturated with products that vary widely in potency, ingredients, and manufacturing standards. To support a more informed decision-making, the following practical checklist outlines key considerations for evaluating multivitamin quality.

The Importance of Vitamin Form and Function

Research shows that more bioavailable forms of certain vitamins, such as folate (B9), B12, B6, B2, vitamin E, and vitamin D may promote superior absorption and metabolic efficiency. These findings may be especially relevant for individuals with metabolic or genetic variations, such as Methylenetetrahydrofolate Reductase (MTHFR) polymorphisms, that may impede conversion of standard vitamin forms into their bioactive counterparts.

B vitamins require activation in the body before they can participate in energy production, neurotransmitter synthesis, methylation, and red blood cell formation. Some individuals have reduced capacity to convert inactive forms into active ones, for example, those with MTHFR polymorphisms. A high-quality multivitamin would usually include the following forms of B vitamins, supporting optimal utilization and bioavailability:

• Riboflavin-5-phosphate (R5P) is the activated coenzyme form of vitamin B2 and plays an important role in cellular energy production, redox reactions, and the metabolism of other B vitamins. Unlike standard riboflavin, which must be phosphorylated in the liver and tissues before it can participate in biochemical pathways, R5P is ready for immediate use by the body.
• Methylated folate or 5-methyltetrahydrofolate (5-MTHF): Studies show that 5-MTHF is more bioavailable and may increase plasma folate more effectively than folic acid in the presence of MTHFR polymorphisms.
• Methylcobalamin, hydroxycobalamin, and adenosylcobalamin are bioavailable forms of vitamin B12 that occur naturally in the human body and animal foods, may help promote vitamin B12 status more efficiently, and exhibit superior bioavailability and safety relative to the synthetic form cyanocobalamin.
• Pyridoxal‑5‑phosphate (P5P or PLP) is the bioactive phosphorylated coenzyme form of vitamin B6, making it the “ready-to-use” form that cells need, while other forms (e.g. pyridoxine hydrochloride) must be enzymatically converted to PLP before they can be utilized by the body.

Vitamin E tocotrienols may promote healthy antioxidant status and provide unique advantages relative to vitamin E tocopherols by supporting cardiometabolic health, liver health, and healthy immune and inflammatory responses.

Vitamin D3 as cholecalciferol has been shown to support vitamin D status more effectively than D2 (ergocalciferol).

Mineral Absorption May Also Depend on the Form

When minerals are bound to organic ligands (e.g., amino acids like glycine) and form chelates their absorption and bioavailability may be improved. Products that rely heavily on inorganic mineral salts (e.g. oxides or sulfates) may be less absorbable. A high-quality multivitamin would include minerals in their chelated forms, such as:

• Magnesium bisglycinate or malate – higher bioavailability than inorganic salts (such as magnesium oxide and magnesium chloride).
• Zinc bisglycinate – superior absorption over zinc oxide.
• Ferrous bisglycinate – better absorption and tolerability compared with other iron supplements.

Additive-Free, Allergen-Conscious Formulas

High-quality multivitamin formulas would avoid unnecessary additives, artificial ingredients, and common allergens. While not all excipients are problematic, research shows that certain additives may provoke adverse events in sensitive individuals:

• Synthetic food dyes have been associated with behavioral and hypersensitivity responses in susceptible populations.
• Artificial sweeteners, such as aspartame, have been associated with neurodegeneration and impaired learning and emotional functioning.
• Titanium dioxide (a whitening agent historically used in supplements) may be related to nanoparticle absorption and immune activation.
• Selecting products that are free from common allergens (e.g., gluten, soy, dairy, and artificial preservatives) may be especially important for sensitive individuals.

Manufacturing Standards: GMP, Testing, and Transparency

Even the best-looking formula on paper can be of low quality if the manufacturer does not follow stringent quality and safety standards, such as:

• Food and Drug Administration (FDA) current Good Manufacturing Practice (cGMP): Companies that comply with cGMPs adhere to rigorous standards for quality, consistency, and safety throughout the manufacturing process.
• Third-party testing including identity, purity, potency, and stability testing. For example:
  
  • NSF Certified for Sport® ensures testing for heavy metals, microbial contamination, and banned substances.
  • ISO-accredited laboratory testing confirms potency, purity, identity, and absence of contaminants through labs formally accredited to international ISO standards.

• Clear traceability and sourcing transparency: Using high-quality inputs (such as grass-fed, non-GMO, and organic ingredients) and clearly disclosing sourcing, vendor qualification procedures, and manufacturing methods.
• Certificate of Analysis (COA): A reputable brand should be able to provide a lot-specific COA showing actual test results for heavy metals (including lead, cadmium, arsenic, and mercury) as well as microbial contaminants and ingredient potency.

Summary

A high-quality multivitamin would be thoughtfully formulated and evidence-based, clinically relevant, and manufactured according to rigorous quality standards.

• Are the vitamins in bioactive forms?

• Are the minerals delivered in chelated, highly absorbable forms?
• Are unnecessary fillers, colorants, or common allergens avoided?
• Does the company follow GMP guidelines and conduct third-party testing?
• Does the brand demonstrate clinical credibility and transparent sourcing?

Together, these considerations offer a practical framework for identifying multivitamins that prioritize both efficacy and safety.

Learn more about multivitamins and nutrition:

Hungry for More: Nutrition Gaps in the Modern American Diet

Daily Multivitamin Supplementation: In Sickness and in Health

What About Whole Food Vitamins?

Nutrient Gaps: 5 Things to Do and Avoid in 2025

By Antonia Toupet, PhD