Analytical ingredient content and variability of adult multivitamin/mineral products: national estimates for the Dietary Supplement Ingredient Database ,

Abstract

Background: Multivitamin/mineral products (MVMs) are the dietary supplements most commonly used by US adults. During manufacturing, some ingredients are added in amounts exceeding the label claims to compensate for expected losses during the shelf life. Establishing the health benefits and harms of MVMs requires accurate estimates of nutrient intake from MVMs based on measures of actual rather than labeled ingredient amounts. Objectives: Our goals were to determine relations between analytically measured and labeled ingredient content and to compare adult MVM composition with Recommended Dietary Allowances (RDAs) and Tolerable Upper Intake Levels. Design: Adult MVMs were purchased while following a national sampling plan and chemically analyzed for vitamin and mineral content with certified reference materials in qualified laboratories. For each ingredient, predicted mean percentage differences between analytically obtained and labeled amounts were calculated with the use of regression equations. Results: For 12 of 18 nutrients, most products had labeled amounts at or above RDAs. The mean measured content of all ingredients (except thiamin) exceeded labeled amounts (overages). Predicted mean percentage differences exceeded labeled amounts by 1.5-13% for copper, manganese, magnesium, niacin, phosphorus, potassium, folic acid, riboflavin, and vitamins B-12, C, and E, and by w25% for selenium and iodine, regardless of labeled amount. In contrast, thiamin, vitamin B-6, calcium, iron, and zinc had linear or quadratic relations between the labeled and percentage differences, with ranges from 26.5% to 8.6%, 23.5% to 21%, 7.1% to 29.3%, 20.5% to 16.4%, and 21.9% to 8.1%, respectively. Analytically adjusted ingredient amounts are linked to adult MVMs reported in the NHANES 2003-2008 via the Dietary Supplement Ingredient Database (http://dsid.usda.nih.gov) to facilitate more accurate intake quantification. Conclusions: Vitamin and mineral overages were measured in adult MVMs, most of which already meet RDAs. Therefore, nutrient overexposures from supplements combined with typical food intake may have unintended health consequences, although this would require further examination.Am J Clin Nutr 2017;105:526-39.

Folic acid preventsC. elegansfolate deficiency indirectly via bacterial uptake of a breakdown product: a route that can also increase bacterial toxicity and ageing

“…As far as we know, no other studies have tested folic acid supplements for the presence of PABA-glu or PABA, but several studies have reported issues with the stability and dissolution of commercial folic acid supplements (Hoag et al, 1997;Sculthorpe et al, 2001). In light of these issues, manufacturers have adopted a policy of 'overages' in order to ensure sufficient folic acid is released in the small intestine following ingestion (Andrews et al, 2017). The presence of PABA-glu and PABA in a commercially available folic acid source (Figure 3) combined the instability of folic acid at the low pH conditions of the stomach, makes it likely that PABA-glu and PABA will be available to the gut microbiota following supplementation.…”

Bacteria increase host micronutrient availability: mechanisms revealed by studies in C. elegans

“…Infusion of [ 3 H] PABA into the colon of rats [67] and piglets [68] could be traced to THFs in the host, demonstrating that bacterial uptake of PABA generates THFs that are absorbed and used in one-carbon metabolism. The lack of regulation of micronutrient supplements but fierce competition on the market has led to a compromise on quality, and folic acid supplements are commonly found to fail tests of stability and dissolution [69][70][71][72]. Combined with the instability of folic acid at low pH [73], it is likely that folic acid breakdown products will be available to the colonic microbiota following long-term supplementation.…”

Weighing the risks of high intakes of selected micronutrients compared with the risks of deficiencies

“…Specific research needs to guide the interpretation of data on program exposure and excessive intake include (1) reevaluation of the ULs, including collection of new data on functional outcomes linked to excessive intake; (2) identification and characterization of biomarkers of MN excess, along with thresholds to indicate increasing risk of toxicity; (3) simplification of dietary intake data collection and analysis, with attention to cataloging the nutrient content of supplements and fortified processed foods; (4) improved tools for estimating the effects of existing and alternative intervention programs on benefits and risks, with special attention paid to intervention program costs; and (5) methods for combining information on deficiency and excess and utilizing this information in policy discussions.…”