Vitamin A (IU), Vitamin A (RE), Thiamin (mg) Riboflavin (mg), Niacin (mg), Pantothenic Acid (mg), Vitamin B-6 (mg), Folate (mcg), Vitamin B-12 (mcg), Ascorbic Acid - Vitamin C (mg), Vitamin D (IU), Vitamin E (a-tocopherol), Vitamin H (mcg)*, Vitamin K (mcg) - phylloquinone.

* Data for Vitamin H (Biotin) was provided by manufacturers.

Ascorbic acid In the current database system, all data for ascorbic acid are listed under Nutrient No. 401, total ascorbic acid, determined by the fluorometric method (AOAC 967.22). Older values which have not been updated are primarily reduced ascorbic acid and were determined by the dichloroindophenol method (AOAC 967.21)

Thiamin was determined chemically by the fluormetric method (AOAC 942.23).

Riboflavin was measured using fluorometric (AOAC 970.65) or microbiological (AOAC 940.33) methods.

Niacin was determined by microbiological methods (AOAC 944.13). The values for niacin are for preformed niacin only and do not include the niacin contributed by tryptophan, a niacin precursor. The term Aniacin equivalent applies to the potential niacin value, that is, to the sum of the preformed niacin and the amount that could be derived from tryptophan. To estimate the amounts of niacin available from foods, the mean value of 60 mg tryptophan is considered equivalent to 1 mg niacin (IOM, 1998). mg Niacin equivalents = mg niacin + (mg tryptophan / 60)

Pantothenic Acid was determined microbiologically (AOAC 945.74 or 992.07).

Vitamins B6 and B12
Vitamin B6 was determined by microbiological methods (AOAC 961.15) and B12 was also determined by microbiological methods (AOAC 952.20). Vitamin B12 is found in foods of animal origin or those containing some ingredient of animal origin, for example, cake that contains eggs or milk. For foods that contain only plant products, the value for vitamin B12 is assumed to be zero. Some reports contain values for vitamin B12 in certain fermented foods (beer, soy sauce, and miso). It is believed that this B12 is synthesized not by the microorganisms responsible for the fermentation of the food, but rather by other contaminating microorganisms. Therefore, one should not consider these foods to be a consistent source of vitamin B12 (Liem et al., 1977).

The Dietary Reference Intakes (DRI) for vitamin B12 recommend that people older than 50 years meet their Recommended Dietary Allowances (RDA) mainly by consuming foods fortified with vitamin B12 or a vitamin B12-containing supplement (IOM, 1998). Since vitamin B12, added as a fortificant, may provide a significant source of the vitamin in the diet, a nutrient number (#578) for "added vitamin B12" has been added to the database. In this release, there are about 230 foods fortified with vitamin B12. The vast majority are breakfast cereals, infant formulas, and plant based meat substitutes. For these foods, the value for total vitamin B12 was used for "added vitamin B12." Only a few cereals containing a milk ingredient would contain any intrinsic vitamin B12. Milk-based infant formulas would contain intrinsic vitamin B12. However, infants are not the population of concern for intake of fortified vitamin B12. Plant-based meat substitutes would not contain intrinsic vitamin B12.

Folate
Values are reported for folic acid, food folate, and total folate reported as µg of dietary folate equivalents (DFEs). These varied folate forms are included as described in the DRI report issued by the Institute of Medicine of the National Academies (IOM, 1998). RDAs for folate are expressed in DFEs, which take into account the greater bioavailability of synthetic folic acid compared with naturally occurring food folate. To calculate DFEs for any single food, it is necessary to have separate values for naturally occurring food folate and added synthetic folic acid in that item.

µg DFE = µg food folate + (1.7 * µg folic acid)

Folate values for foods analyzed through NFNAP are generated using the trienzyme microbiological procedure (Martin et al., 1990). Microbiological methods measure total folate; for enriched foods, folic acid and food folate are not distinguished from each other. Therefore, to be able to calculate DFE, multi-ingredient enriched foods are analyzed by an additional microbiological procedure without enzymes to estimate the amount of added folic acid (Chun et al., 2006). Food folate is then calculated by difference. The addition of folic acid to enriched cereal-grain products subject to standards of identity began in the United States on January 1, 1998 (CFR, Title 21, Pts. 136B137). These products include flour, cornmeal and grits, farina, rice, macaroni, noodles, bread, rolls, and buns. Folic acid may continue to be added (with some restrictions on amounts) to breakfast cereals, infant formulas, medical foods, food for special dietary use, and meal replacement products.

For unenriched foods, food folate would be equivalent to total folate since folic acid (pteroylmonoglutamic acid) occurs rarely in foods. Therefore, the same value with its number of data points and standard error, if present, is used for total folate and food folate. The folic acid value is assumed to be zero.

For enriched cereal-grain products with standards of identity (flour, cornmeal and grits, farina, rice, macaroni, noodles, bread, rolls, and buns), the folic acid value is calculated by subtracting the analytical folate value before fortification from the analytical value for the fortified product. Enriched ready-to-eat (RTE) cereals have generally included folic acid fortification for over 25 years. Therefore, food folate values (before fortification) were not readily available for these products. Food folate was estimated by means of the NDBS formulation program for a variety of high-consumption cereals. Mean folate values were calculated for categories of RTE cereals based on grain content. Added folic acid was then calculated by subtracting estimated food folate from the total folate content. Generally, food folate values represent a small proportion of the total folate in the fortified products.

Vitamin A
Beginning with SR15 (2002), in addition to the international units (IUs) that have been reported in the past, we reported values for vitamin A in µg of retinol activity equivalents (RAEs) and µg of retinol. Values in µg of retinol equivalents (REs) were dropped from the database. This change responds to new reference values for vitamin A issued by the Institute of Medicine of the National Academies (IOM, 2001). Along with the new DRIs, the panel recommended changing the factors used for calculating vitamin A activity from the individual provitamin A carotenoids and introduced RAE as a new unit for expressing vitamin A activity. One µg RAE is equivalent to 1 µg of all-trans-retinol, 12 µg of all-trans-ß-carotene, or 24 µg of other provitamin A carotenoids. The RAE conversion factors are based on recent studies that show that the conversion of provitamin A carotenoids to retinol is only half as great as previously thought.

Vitamin A in IU will continue to be reported because it is still the unit used for nutrition labeling. One IU is equivalent to 0.3 µg retinol, 0.6 µg ß-carotene, or 1.2 µg other provitamin-A carotenoids (NAS/NRC, 1989).

Individual carotenoids, ß-carotene, a-carotene, ß-cryptoxanthin, lycopene, and lutein+zeaxanthin are reported. The analytical data are from NFNAP, generated using HPLC methodology (AOAC 941.15) and from the scientific literature. Most analytical systems do not separate lutein and zeaxanthin, so these carotenoids are shown combined. These values supersede those in Holden et al., 1999. Vitamin A values in IU and RAE were calculated from the individual carotenoids (ß- carotene, a-carotene, and ß-cryptoxanthin) using the appropriate factors. For food items used in the FNDDS, carotenoid values were imputed if analytical data were not available. For many of these items data were only available for vitamin A in IU. However, the variability in carotenoid levels due to cultivar, season, growing area, etc., as well as rounding within the NDBS, increases the difficulty in matching the calculated vitamin A values from imputed individual carotenoids to the existing IU values. As a result, the vitamin A IU value should agree within ±15 IU of the value calculated from individual carotenoids.

When individual carotenoids are not reported for plant foods (such as fruits, vegetables, legumes, nuts, cereal grains, and spices and herbs), µg RAE were calculated by dividing the IU value by 20.

In foods of animal origin, such as eggs, beef, pork, poultry, lamb, veal, game, and fish (except for some organ meats and dairy), all of the vitamin A activity is contributed by retinol. For these foods, when analytical data were not available, µg RAE and µg of retinol were calculated by dividing the IU value by 3.33.

In foods that contain both retinol and provitamin A carotenoids, the amount of each of these components must be known to calculate RAE. Most of the vitamin A data in the database were received as IU. Therefore, the amounts of the provitamin A carotenoids and retinol had to be estimated based on the amount of retinol and provitamin A carotenoids in the ingredients. Once the components had been estimated, µg RAE were calculated as (IU from carotenoids/20) + (IU from retinol/3.33). µg of retinol were calculated as IU from retinol/3.33.

Vitamin D - Much of the data for vitamin D were published earlier in the Provisional Table (PT-108) (Weihrauch and Tamaki, 1991). Values for breakfast cereals were updated based on data received from the food industry; values for other food items were updated using data generated under NFNAP using liquid chromatography (AOAC 995.05 or 982.29). These new values supersede those in PT-108.

Vitamin E
Vitamin E activity for the RDA as defined by the DRI report (IOM, 2000) is now limited to the naturally occurring form and three synthetic forms of a-tocopherol. For this reason, a-tocopherol equivalents, which included vitamin E activity from a-, ß-, g-, and d-tocopherols and a-, ß-, and g-tocotrienols, were dropped from the database in SR16. Tocopherols were determined by gas-liquid chromatography (GLC) or high-performance liquid chromatography (HPLC) (Lee et al., 1999). For those items in FNDDS, values are presented for a-tocopherol. If analytical data were unavailable, values for a-tocopherol were imputed. When available, values are also presented for the other tocopherols.

In the DRI report for Vitamin E, different factors were used to calculate the milligram amount of a-tocopherol from IU of vitamin E (IOM, 2000). The factors vary depending upon the chemical form of a-tocopherol used to fortify the food where mg of a-tocopherol in food, fortified food, or multivitamin

= IU of the RRR-a-tocopherol compound × 0.67 and
= IU of the all rac-a-tocopherol compound × 0.45.

Before SR16-1, the conversion factor for RRR-a-tocopherol was used for all vitamin E fortified foods. New a-tocopherol values have been calculated for breakfast cereals, most infant formulas and a few other foods that are fortified with vitamin E, where we have confirmed that all rac-a-tocopherol was the form added. For more information about vitamin E in breakfast cereals, see the article in the January 2004 issue of the American Journal of Clinical Nutrition by Leonard et al. (2004).

The basis of the vitamin E tolerable upper intake level (UL), another reference value in the DRI report, was established using all forms of supplemental a-tocopherol (IOM, 2000)." A new nutrient number (#573) has been added to identify quantities of "added vitamin E." In this release, there are 100 food items that have values for added vitamin E greater than 0. For the majority of these food items the form added is synthetic vitamin E (all rac-a-tocopherol). To relate intakes of supplemental a-tocopherol to the UL, values for "added vitamin E" should be multiplied by 2 when the added form is synthetic vitamin E. Although the 2S-stereoisomers do not contribute to vitamin E activity for the RDA (IOM, 2000), they do contribute to the UL. Items that are fortified with RRR-a-tocopherol (natural vitamin E) are identified by a footnote and the added vitamin E can be used directly for contribution to the UL. The majority of foods that are fortified with vitamin E are infant formulas and breakfast cereals. For these foods, the value for total vitamin E was used for "added vitamin E"; the small amount of intrinsic vitamin E was not considered. In fortified peanut butter, the intrinsic vitamin E was calculated since it is a substantial amount.

Vitamin K - Much of the data for vitamin K were generated under NFNAP and supersede the values in the Provisional Table (PT-104) (Weihrauch and Chatra, 1994). Vitamin K is extracted with hexane, purified with solid phase extraction using silica columns, and quantitated using HPLC with chemical reduction and fluorescence detection. Losses are corrected using vitamin K1 as internal standard (Booth et al. 1994).

Related topics include Proximates, Minerals, Amino Acids, Fatty Acids.