Study Methodology

How We Determine Effectiveness Scores

We use four scientific criteria to compare multivitamin brands. We developed each criterion based on peer-reviewed evidence available in the latest published medical literature.

The four comparison criteria are as follows:


Your body needs 13 types of vitamins and at least as many different types of minerals in order to function properly. This criterion has to do with how closely the dosage of vitamins and minerals in each product follow the Optimal Daily Intake index. Optimal composition means you receive the nutrients in the most effective combinations and dosage amounts.

Composition is 25% of the final score.


Does the potency of the ingredients found in the product meet or exceed the potency levels outlined in the Optimal Daily Intake index? Store brand supplements often contain low-quality forms of nutrients, which are not as potent as higher-quality nutrients.

Potency is 25% of the final score.


Bioavailable nutrients are easily and efficiently absorbed by the body. Does the product contain vitamins and minerals in their most absorbable forms, such as organic acid complexes, mixed carotenoids, or amino acid chelates?

Bioavailability is 25% of the final score.


When it comes to supplements, we put safety first. When determining the Safety scores, we look for two things: harmful additives and potential risk of overdose. We prefer a less potent, but safer product, rather than a product packed in nutrients that are well in excess of the Optimal Daily Intake.

Safety is 25% of the final score.

From these four criteria, we calculate an Effectiveness Score. A score near 10 represents a supplement with the characteristics for optimal nutrition.

Conversely, a score near 0 represents a product possessing few, if any, of the characteristics for optimal nutrition.

What is the Optimal Daily Intake for each vitamin and mineral?

The Optimal Daily Intake (ODI) represents the ideal quantities of vitamins and minerals individuals need to take each day according to the latest research in the area of nutritional supplementation.

Please note that these ODI values are higher than the current recommended daily allowance (RDA) or dietary reference intakes (DRI) as published by the U.S. Food and Nutrition Board.

The RDA and DRI values are too low and not optimal for many nutrients.

The ODI includes the 26 essential ingredients, listed in the table below with their recommended daily dosage:

# Vitamin/Mineral Dosage
1 Vitamin A (Beta carotene) 5000 IU
2 Vitamin B1 (Thiamine) 5 mg
3 Vitamin B2 (Riboflavin) 5 mg
4 Vitamin B3 (Niacin) 22 mg
5 Vitamin B5 (Pantothenic acid) 15 mg
6 Vitamin B6 5 mg
7 Vitamin B7 (Biotin) 350 mcg
8 Vitamin B9 (Folic Acid) 400 mcg
9 Vitamin B12 12 mcg
10 Vitamin C 200 mg
11 Vitamin D3 2000 IU
12 Vitamin E 60 IU
13 Vitamin K2 (Menaquinone) 150 mcg
14 Calcium 1300 mg
15 Chloride 3400 mg
16 Chromium 120 mcg
17 Copper 2 mg
18 Iodine 150 mcg
19 Iron 15 mg
20 Magnesium 420 mg
21 Manganese 2.3 mg
22 Molybdenum 75 mcg
23 Phosphorus 1250 mg
24 Selenium 80 mcg
25 Vanadium 75 mcg
26 Zinc 15 mg

List of medical literature used in the study

  1. Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. National Academy of Sciences. Institute of Medicine. Food and Nutrition Board. Retrieved 2016-05-01.
  2. Tolerable Upper Intake Limits for Vitamins And Minerals. European Food Safety Authority. ISBN 92-9199-014-0.
  3. "Dietary Reference Intakes Tables [Health Canada]". Retrieved 2016-05-01.
  4. "Council for Responsible Nutrition". Retrieved 2016-05-01.
  5. "FDA Information for Consumers (Dietary Supplements)". Retrieved 2016-05-01.
  6. Recommended Dietary Allowances: 10th Edition". Retrieved 2016-05-01.
  7. Ross AC, Manson JE, Abrams SA, Aloia JF, Brannon PM, Clinton SK, Durazo-Arvizu RA, Gallagher JC, Gallo RL, Jones G, Kovacs CS, Mayne ST, Rosen CJ, Shapses SA (January 2011). "The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know". J. Clin. Endocrinol. Metab. 96 (1): 53–8. doi:10.1210/jc.2010-2704. PMC 3046611. PMID 21118827.
  8. "Vitamins: what they do and where to find them (EUFIC)". European Food Information Council. 10-12-2010. Retrieved 2016-05-01. "Vitamin D"
  9. "Linus Pauling Vindicated; Researchers Claim RDA For Vitamin C is Flawed" (Press release). Knowledge of Health. July 6, 2004. Retrieved 2016-05-01.
  10. DRI, Dietary reference intakes: for calcium, phosphorus, magnesium, vitamin D, and fluoride. Washington, D.C: National Academy Press. 1997. p. 250. ISBN 0-309-06350-7. Nutrition
  11. Padayatty, Sebastian J.; Katz, Arie; Wang, Yaohui; Eck, Peter; Kwon, Oran; Lee, Je-Hyuk; Chen, Shenglin; Corpe, Christopher et al. (2003). "Vitamin C as an antioxidant: evaluation of its role in disease prevention.". Journal of the American College of Nutrition 22 (1): 18–35. PMID 12569111.
  12. Chapter 4, Vitamin A of Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc, Food and Nutrition Board of the Institute of Medicine, 2001
  13. Adams, J. S.; Hewison, M. (2010). "Update in Vitamin D". Journal of Clinical Endocrinology & Metabolism 95 (2): 471–8. doi:10.1210/jc.2009-1773. PMC 2840860. PMID 20133466.
  14. Holick, MF (2004). "Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis". The American Journal of Clinical Nutrition 79 (3): 362–71. PMID 14985208.
  15. "Dietary Supplement Fact Sheet: Vitamin D". Office of Dietary Supplements (ODS). National Institutes of Health (NIH). Retrieved 2016-05-01.
  16. "Recommended Daily Intakes and Upper Limits for Nutrients". Retrieved 2016-05-01.
  17. Gropper SS, Smith JL, Grodd JL (2004). Advanced Nutrition and Human Metabolism (4th ed.). Belmont, CA. USA: Thomson Wadsworth. pp. 260–275.
  18. Levine, M; Conry-Cantilena, C; Wang, Y; Welch, RW; Washko, PW; Dhariwal, KR; Park, JB; Lazarev, A et al. (1996). "Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance". Proceedings of the National Academy of Sciences of the United States of America 93 (8): 3704–9. doi:10.1073/pnas.93.8.3704. PMC 39676. PMID 8623000.
  19. Addition of Vitamins and Minerals to Food, 2005". Health Canada. Retrieved 2016-05-01.
  20. "National Nutrient Database". Nutrient Data Laboratory of the US Agricultural Research Service. Retrieved 2016-05-01.
  21. Huang, Han-Yao; Caballero, Benjamin; Chang, Stephanie; Alberg, Anthony J.; Semba, Richard D.; Schneyer, Christine; Wilson, Renee F.; Cheng, Ting-Yuan; Prokopowicz, Gregory; Barnes, George J. II; Vassy, Jason; Bass, Eric B. (May 2006). "Multivitamin/mineral supplements and prevention of chronic disease". Evid Rep Technol Assess (Full Rep) (139): 1–117. PMID 17764205.
  22. Woodside J, McCall D, McGartland C, Young I (2005). "Micronutrients: dietary intake v. supplement use". Proc Nutr Soc 64 (4): 543–53.doi:10.1079/PNS2005464. PMID 16313697.
  23. Shenkin A (2006). "The key role of micronutrients". Clin Nutr 25 (1): 1–13. doi:10.1016/j.clnu.2005.11.006. PMID 16376462.
  24. McKeown NM, Jacques PF, Gundberg CM, et al (June 2002). "Dietary and non-dietary determinants of vitamin K biochemical measures in men and women". J. Nutr. 132 (6): 1329–34. PMID 12042454.
  25. "Vitamin and mineral requirements in human nutrition, 2nd edition" (PDF). World Health Organization. 2004. Retrieved 2016-05-01.
  26. A.C. Carr, B. Frei, "Toward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans" American Journal of Clinical Nutrition, Vol. 69, No. 6, 1086-1107, June 1999.
  27. Preedy VR; Watson RR; Sherma Z (2010). Dietary Components and Immune Function (Nutrition and Health). Totowa, NJ: Humana Press. pp. 36; 52.ISBN 1-60761-060-4.
  28. Combs, Gerald F. (2008). The Vitamins: Fundamental Aspects in Nutrition and Health (3rd ed.). Burlington: Elsevier Academic Press.ISBN 9780121834937.
  29. "Nutrient reference values for Australia and New Zealand" (PDF). National Health and Medical Research Council. 2005-09-09. Retrieved 2016-05-01.