Bioavailability (BA) of vitamin B6 (B-6) from foods may be
limited. The knowledge of the BA of B6 from food is important in
that this would help to understand if the B6 present in the diet of
individuals will meet the requirements for this vitamin.
The purpose of this study was a) to develop a method to measure
the level of glycosylated vitamin B6 (GB6) in the foods; b) to
investigate the relative vitamin B6 bioavailability from tuna (T),
whole wheat bread (WW), and peanut butter (PB) in humans; c)
to follow the excretion pattern of GB6 and relate this to the occurrence
of the GB6 in foods.
To measure the level of GB6 in foods, the B6 content was determined
microbiologically before and after treatment of the foods with β-glycosidase as well as after acid hydrolysis. Animal products
contained no measurable amount of GB6, but grain and legumes had
6-75% of total B6 present as GB6. Of the fruits and vegetables
analyzed, orange juice (47%) and raw carrots (51%) had the highest
GB6 levels.
Relative BA of B6 from T, WW, and PB was investigated in eight
healthy men in a 52-day study (10-day adjustment and three 14-day
experimental periods). B5 intake was set at 1.6 mg/day, with 50%
coming from one experimental food and 50% from a basal diet. Urine
was analyzed for 4-pyridoxic acid (4PA) and B6; feces for B6; and
plasma for pyridoxal-5'-phosphate (PLP). Of these four indices
used to assess B6 bioavailability, 4PA and urinary B6 were significantly
(p < 0.01) higher in T than in either WW or PB periods. When
T was fed, fecal B6 excretion was significantly (p < 0.01) lower than
when PB was fed. The B6 in WW and PB was 75% and 63% as available
as that from T, respectively.
The urine from the last day of each period for five subjects and
the last fecal composite for each period was analyzed for the nonconjugated
B6 and GB6. The majority of B6 in the feces was in the
non-conjugated form. No GB6 was detected in the feces during either
the T or PB periods. Only 4% of total B6 in the feces was in the
GB6 form when WW was fed. GB6 was found in the urine in all periods.
The level of GB6 in the food was inversely related to
B6 bioavailability in foods fed to humans in our study and in
three other human studies. It appears that the level of
GB6 in foods could be used as an index of B6 bioavailability in
foods. / Graduation date: 1984
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27163 |
| Date | 06 July 1983 |
| Creators | Kabir, Gholamhossein |
| Contributors | Leklem, James E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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