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FREQUENTLY ASKED QUESTIONS (FAQ)
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Many answers to your questions can be found by clicking the DSID web links to access various parts of the website. Responses to frequently asked questions (FAQs) are below. |
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1. What is DSID-2?
The Dietary Supplement Ingredient Database (DSID), an initiative of the Office of Dietary Supplements at NIH, was developed at the Nutrient Data Laboratory, U.S. Department of Agriculture. DSID research has focused first on priority ingredients in multivitamin/minerals
(MVMs), since these products are the most commonly consumed dietary supplements in the United States. DSID-2 is the second release of DSID, which provides access to information on estimated levels of ingredients in children’s and adult multivitamin/mineral
(MVM) products. The adult MVM data in DSID-2 replace DSID-1, the first data release, which provided access to information on estimated levels of ingredients in adult MVMs.
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2. Why was the Dietary Supplement Ingredient Database created?
The Dietary Supplement Ingredient Database (DSID) was created to: (a) develop reliable estimates of dietary ingredients and other bioactive components in dietary supplement products; (b) support improved dietary intake assessments in research by providing
analytical estimates of the ingredient content of marketed dietary supplements; (c) report on analyzed levels of ingredients relative to labeled values; and (d) release and maintain a publicly available on-line composition database. By using data in the DSID,
analytically-based estimates of nutrient content of specific types of dietary supplements can be combined with supplement intake records to estimate total nutrient intake from food plus supplements. These estimates can assist researchers to make more accurate
quantitative intake assessments and evaluate the nutritional status of the U.S. population.
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3. What data and formats are provided in DSID-2?
DSID-2 provides estimated levels of vitamins and minerals for a range of labeled levels in children’s MVMs and adult MVMs. A variety of files and formats are provided. DSID-2 includes: (a) Statistical results; (b) Data file description documents; (c) Research summaries; (d) Data files containing predicted ingredient amounts; (e) Data files containing DSID applications to products in the National Health and Nutrition Examination Survey (NHANES) for specific
cycle years of the surveys; and (f) Ingredient calculators.
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4. Why were these specific ingredients in multivitamin/minerals (MVMs) chosen for inclusion in DSID?
A consortium of federal partners convened by the Office of Dietary Supplements established DSID priorities for products and ingredients of public health and research interest. MVM products were identified as a top priority because they are the most commonly reported dietary supplement in the NHANES. The vitamins and minerals for analysis were determined based on prevalence of consumption, public health interest, and the availability of reliable analytical methods for specific compounds.
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5. What agencies have collaborated with NDL to develop the DSID??
NDL's major collaborator for the DSID project is the NIH Office of Dietary Supplements http://dietary-supplements.info.nih.gov/
Others include:
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6. How were the DSID prediction calculations developed?
The data used in the prediction calculations were derived from nationwide studies conducted to determine ingredient levels for representative multivitamin/mineral products (n = 3 or more vitamins, with or without minerals). Products were purchased from various market channels and analyzed for specific ingredients at qualified laboratories. Results from these studies were statistically evaluated using regression analysis. Details about each study can be accessed at the Research Summaries section of this website.
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7. What is the “Predicted Mean Value”?
The “Predicted Mean Value”
is the estimated amount of that ingredient at a specific labeled level, as determined by regression analysis. Predicted means and other statistical parameters have been established within a defined regression range for each ingredient. For example, the defined regression range for iodine is labeled levels of 15 to 150 mg for adults and 12.8 to 150 mg for children ages 4 and older. For labeled levels above and below those amounts, predicted amounts are not available.
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8. What are the “Standard Error for Predicted Mean” and the “Standard Error for Predicted Observation”?
The “Standard Error for Predicted Mean” is the standard deviation of a sampling distribution of means, calculated in this study by dividing the standard deviation by the number of analytical values. This is the error associated with the predicted mean for a large population of supplements labeled at the same level.
The “standard error for predicted observation” estimates the error associated with the predicted mean for a single new observation, which in this case is any individual MVM supplement product.
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9. How are the “Predicted Mean Value”, “Standard Error for the Predicted Mean” and “Standard Error for the Predicted Observation” calculated?
These values are calculated from statistical data provided in Table 1 or Table A1 of the DSID-2 release. An Example Calculations document provides definitions and instructions for applying the data in Table 1 and A1 to labeled levels of MVM supplement products. A spreadsheet version of the Example Calculations is available in the second tab of the Table 1 and Table A1 Excel spreadsheet.
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10. Why are ingredients reported in different units, such as milligrams (mg), micrograms (mcg), or International Units (IU) in the DSID?
The DSID uses the FDA’s established units of measure for reporting ingredient amounts on labels, since the final DSID results are compared to labeled levels. See Appendix A for a listing of ingredients, units and other reference information concerning DSID
release data.
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11. What is the difference between milligrams, micrograms and IU?
In the metric system, 1000 milligrams (mg) is a unit of mass equal to 1 gram and 1000 micrograms (mcg) is equal to 1 milligram (mg).
An IU (International Unit) is a unit of measurement for vitamins and other specific biologically active substances. The equivalency of one IU differs from substance to substance and is established by international agreement for each substance. It is a measure of biological activity, rather than quantity.
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12. Were conversion factors for the natural and synthetic forms of vitamin E applied to the calculations of vitamin E in IUs for the DSID?
For the DSID, the results from the chemical analysis of vitamin E (as alpha-tocopherol) in dietary supplements are reported by the laboratory in mg/g. This amount is converted to IU/serving using the weight of one serving of the product in grams and applying
the appropriate conversion factor. The analytical result in IU is then compared to the label value in IU to calculate the percent difference from the labeled amount.
The conversion factor used for each analytical result is dependent upon whether the alpha-tocopherol being measured is in a natural or synthetic form. When calculating IU equivalents, NDL uses the vitamin E labeling guidelines for manufacturers, provided
by the Food and Drug Administration (FDA). These are based on the 1968 RDAs for converting the quantity of synthetic vitamin E as dl-alpha-tocopherol from IU to mg, which is IU *0.9. (In contrast, the 2003 Dietary Reference Intake (DRI) guidelines are based
on bioavailability standards for converting the quantity of synthetic vitamin E as dl-alpha-tocopherol from IU to mg, which is IU *0.45.)
For natural vitamin E as d-alpha-tocopherol, the conversion of IU units to mg units is the same for both FDA labeling guidelines and the 2003 DRI, using IU*0.67 = 1 mg.
For comparison to labeled levels, vitamin E was calculated using these formulas:
- To convert Vitamin E if the product label has dl-alpha-tocopherol as the ingredient:
From IU to mg: IU*0.9 = mg
For example: 30 IU*0.9 = 27 mg
From mg to IU: mg/0.9 = IU
- To convert Vitamin E if the product label has d-alpha-tocopherol as the ingredient:
From IU to mg: IU *0.67= mg
For example: 30 IU*0.67 = 20.1 mg
From mg to IU: mg/0.67= IU
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13. For vitamins A and D in the DSID, what factors were used for converting from 'mg' or 'mcg' to 'IU'?
For the DSID, the results from the chemical analysis of vitamins A (as beta-carotene and retinol) and vitamin D in dietary supplements are reported by the laboratory in mcg/g. This amount is converted to IU/serving using the weight of one serving of the product in grams and applying the appropriate conversion factor. The analytical result in IU is then compared to the label value in IU to calculate the percent difference from the labeled amount. Conversion factors for 1 IU of Vitamins A and D are:
- Vitamin A: 1 IU is equivalent to 0.3 mcg retinol, or 0.6 mcg beta-carotene;
- Vitamin D: 1 IU is equivalent to 0.025 mcg cholecalciferol or ergocalciferol;
For the calculations, the formulas are:
- To convert Vitamin A as retinol:
From IU to mcg: IU*0.3 = mcg;
For example: 5000 IU*0.3 = 1500 mcg;
From mcg to IU: mcg/0.3 = IU
- To convert Vitamin A as beta-carotene:
From IU to mcg: IU*0.6 = mcg;
From mcg to IU: mcg/0.6 = IU
- To convert Vitamin D:
From IU to mcg: IU*0.025 = mcg
For example: 400 IU*0.025 = 10 mcg
From mcg to IU: mcg/0.025 = IU
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14. For what dietary supplements can these predictions be used?
DSID predicted values are based on analytical data for ingredients in adult multivitamin/mineral (MVM) and children’s MVM products. MVMs in DSID studies are defined as dietary supplements containing three or more vitamins, with or without minerals.
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15. How can these predicted values be used in nutrition studies?
DSID can support studies and surveys that estimate ingredient intake contributed by dietary supplements. DSID analytically-based estimates of mean and variability can replace label information. These estimates can allow researchers to more accurately assess the nutritional status of the U.S population.
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16. How do I know what amount of each nutrient I need each day?
The "Daily Value" (DV) amounts shown on labels are based on Reference Daily Intakes of essential vitamins and minerals and Daily Reference Values (which apply to fat, saturated fat, cholesterol, carbohydrate, protein, fiber, sodium, and potassium). For further details, refer to Daily Reference Intake (DRI) amounts recommended by the Institute of Medicine (IOM), accessible at http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=3&tax_subject=256&topic_id=1342&level3_id=5140 (accessed February 16, 2012)
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17. How did you use the term “serving size” in DSID research?
DSID data are reported in ‘per serving’ amounts. ‘Per serving’ is the common term used on the Supplement Facts label to indicate the number of units (tablets, capsules, gel caps, teaspoons, etc) recommended for consumption per occasion. The serving size is product-specific, and may be one or more units. More than one recommended serving size can be listed, especially if two children's age groups are noted. Data are reported as ingredient amounts per serving in the DSID release.
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