Journal of the American College of Nutrition

ISSN: 0731-5724 (Print) 1541-1087 (Online) Journal homepage: http://www.tandfonline.com/loi/uacn20

Effect of dietary fiber on the vitamin B6 status among vegetarian and nonvegetarian elderly (Dutch nutrition surveillance system). M R Löwik, J Schrijver, H van den Berg, K F Hulshof, M Wedel & T Ockhuizen To cite this article: M R Löwik, J Schrijver, H van den Berg, K F Hulshof, M Wedel & T Ockhuizen (1990) Effect of dietary fiber on the vitamin B6 status among vegetarian and nonvegetarian elderly (Dutch nutrition surveillance system)., Journal of the American College of Nutrition, 9:3, 241-249, DOI: 10.1080/07315724.1990.10720375 To link to this article: http://dx.doi.org/10.1080/07315724.1990.10720375

Published online: 02 Sep 2013.

Submit your article to this journal

Article views: 5

View related articles

Citing articles: 1 View citing articles

Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=uacn20 Download by: [Temple University Libraries]

Date: 13 June 2016, At: 08:56

Effect of Dietary Fiber on the Vitamin B 6 Status Among Vegetarian and Nonvegetarian Elderly (Dutch Nutrition Surveillance System) Michiel R. H. Löwik, MSc, MBA, Jaap Schrijver, PhD, Henk van den Berg, PhD, Karin F. A. M. Hulshof, RD, Michel Wedel, MSc, and Theo Ockhuizen, PhD TNO-CIVO Toxicology and Nutrition Institute, Departments of Human Nutrition and Clinical Biochemistry, Zeist, The Netherlands

Downloaded by [Temple University Libraries] at 08:56 13 June 2016

Key words: dietary fiber, protein, vitamin B6, bioavailability, elderly people, vegetarianism, dietary interrelationships To obtain more insight into the effect of dietary fiber on vitamin B6 status among elderly people, we studied dietary interrelationships as well as associations between dietary intake and plasma pyridoxal-5'-phosphate (PLP) and cofactor stimulation of aspartate aminotransferase in erythrocytes (EAST-AC) among 441 nonvegetarian (aged 65-79) and 32 vegetarian elderly (aged 65-94). EAST-AC was found to be inversely related with intake of vitamin B6 and dietary fiber in bivariateregressionanalyses. After adjustment for age, intake of energy, protein, and fiber, the intake of vitamin B6 was still inversely related with EAST-AC. The association between EAST-AC and dietary fiber disap­ peared in the multivariate analysis, whereas total protein intake proved to be positively related with EAST-AC in the multivariate analysis only. The differences between bi- and multivariate analyses are most likely due to the observed interrelationships between intake of vitamin B6,fiber,and protein. It is concluded that dietary fiber does not have a significant impact on the vitamin B6 status among Dutch elderly people, since only protein (positively) and vitamin B6 (inversely) intake appeared to be related with EAST-AC in the multivariate analysis.

INTRODUCTION A marginal intake and status of vitamin B 6 is fairly common among the elderly in affluent societies [1-4]. Kant et al [5] found lower plasma pyridoxal-5'-phosphate (PLP) levels among elderly people than among younger adults, but no significant differences in vitamin B 6 intake among the age groups were observed (neither in absolute amount nor expressed per gram protein). Since the vitamin B 6 requirement depends on the protein content of the diet [6-8], a higher consumption of fruits, vegetables, and potatoes results in a higher vitamin B6:protein ratio of the diet and hence is considered to be preventive against a marginal vitamin B6 status [4]. However, most of these products are rich in dietary fiber, and little is known about the possible inhibitory effect of dietary fiber on the utilization of vitamin B 6 [9-13]. Several studies indicate a lower bioavailability of vitamin B 6 of vegetable origin as compared to animal products [11-13]. Since the customary vegetarian diet is relatively high in fiber [14], insufficient amounts of nutrients may be available from that diet. Schultz and

Leklem [15], studying the bioavailability of vitamin B 6 among middle-aged and elderly vegetarian and non­ vegetarian women by just comparing the vitamin B 6 status of these groups, did not find an adverse effect of crude fiber on vitamin B 6 status. However, a food con­ sumption pattern consists of a complex set of interrelated nutrients [16]. Any evaluation of the bioavailability of vitamin B6 should at least take into account the intake of vitamin B 6 as well as of protein and dietary fiber. To assess the effect of dietary fiber on vitamin B 6 status among Dutch elderly on their habitual diets, we used data on vitamin B6 status as well as relevant infor­ mation on the dietary intake of apparently healthy Dutch elderly and included vegetarian elderly to obtain more data in the upper range of the intake of dietary fiber.

SUBJECTS AND METHODS In 1984-85, a nationwide survey among 539 elderly people and in 1986 a similar survey among 44 vegetarian elderly were carried out within the framework of the

Address reprint requests to Michiel R. H. Löwik, Depanment of Human Nutrition, TNO-CIVO Toxicology and Nutrition Institute, P.O. Box 360,3700 AJ Zeist, The Netherlands.

Journal of the American College of Nutrition, Vol. 9, No. 3, 241-249 (1990) © 1990 John Wiley & Sons, Inc.

CCC 0731-5724/90/030241-09$04.00

Downloaded by [Temple University Libraries] at 08:56 13 June 2016

Diet and Vitamin Be Status in the Elderly Dutch Nutrition Surveillance System [17]. The study design of the national survey and procedures have been described in detail [4,18,19]. Verbal consent was ob­ tained after the nature of the study was explained by a letter. The study was approved by the TNO-CIVO Toxicology and Nutrition Institute's external Medical Ethics Committee. The response rate in the random sample from a vegetarian elderly community in The Netherlands was 67%; 44 persons were included in the study who met the following criteria: aged 65 or over, apparently healthy, Caucasian, and vegetarian (not using meat, fish, or poultry). For the purpose of the present study 57 elderly using drugs known to potentially affect vitamin B 6 require­ ment, metabolism, and/or status were excluded from the analysis [20,21]. Furthermore, 10 subjects with frank anemia (hemoglobin < 7.5 mmol/L) and 43 elderly using vitamin B 6 supplements were excluded. Data on 441 nonvegetarians (aged 65-79 years) and 32 vegetarians (aged 65-94 years) remained for the analyses. Three of these vegetarians were lacto-vegetarians; the remaining were lacto-ovo-vegetarians. Food consumption data were obtained by a dietitian with a modified version of the dietary history method with crosscheck [22]. Conversion of the dietary informa­ tion to the intake of energy and nutrients was established with a computerized version (edition of 1984) of the Dutch Food Composition Table [23]. Vitamin B 6 losses due to normal preparation practices are accounted for in this table. Dietary fiber refers to plant polysaccharides and lignin that are resistant to hydrolysis in the human digestive tract. The main components of dietary fiber are cellulose, hemicelluloses, pectic substances, and lignin. In the Dutch Food Composition Table [23] dietary fiber is the sum of the above-mentioned components. Infor­ mation on demographic variables, lifestyle, clinical con­ dition (including current drug use), and usage of nutri­ tional supplements was collected. A venous blood sample (nonfasted) was obtained for hématologie, biochemical, and routine clinical analyses [19]. Evaluation of the vitamin B 6 status was based on the biochemical measurement of the plasma concentration of pyridoxal-5'-phosphate (PLP) (measured by a radioenzymatic assay with tyrosine decarboxylase apoenzyme; singular extraction, assay in duplicate) and erythrocyte aspartate aminotransferase (EAST; EC 2.6.1.1) activity before and after in vitro stimulation by PLP (at the cel­ lular level). The EAST activity with and without added PLP was measured in duplicate with a kinetic assay on a Hitachi 705 automatic analyzer and expressed as an ac­ tivation coefficient (EAST-AC) [van den Berg, personal communication]. The EAST activity was measured in all available blood samples. Plasma PLP concentrations

242

were determined in all blood samples from vegetarians, but in a random subsample (n = 108) of the national sur­ vey stratified as in the original group of 539 persons. The data analyzed by analysis of variance with gender and dietary style as factors and by (multiple) linear regression. The interrelationships between intake of protein (total, vegetable, and animal), dietary fiber, and vitamin B 6 were assessed through the calculation of correlations. Data were analyzed with the BMDP statisti­ cal computer package [24]. All statistical tests were twotailed. Effects with a p value lower than 0.05 were con­ sidered significant.

RESULTS In Table 1 information is presented on general and some dietary characteristics classified according to (non)vegetarianism and gender. On the average, men had a higher body weight and a higher intake of energy, protein, fat, total carbohydrates, dietary fiber, and vitamin B6. In relative terms, only the lower percentage of energy from protein for men appeared to differ sig­ nificantly from that of women. Among nonvegetarians the intake of alcohol (both in grams and in energy%) was higher for men than for women. Compared to non­ vegetarians, the mean body weight, body mass index, and energy intake of vegetarians was lower; in the vegetarian diet, less energy was derived from protein and alcohol, and more from carbohydrates. Vegetarians had a higher intake of dietary fiber (absolute and per MJ) and vitamin B 6 (per MJ and per gram of protein). Vegetarians had a vegetable-animal protein ratio of 1.01, whereas this ratio was 0.45 among nonvegetarians. In the vegetarian diet virtually all (91%) animal protein originated from milk and milk products, whereas only 14% of the vitamin B6 was derived from these products in the vegetarian diet. Table 2 presents the vitamin B 6 status classified ac­ cording to gender and (non)vegetarianism. Except for a somewhat higher mean plasma PLP level among vegetarians, no significant differences were observed in the vitamin B 6 status between genders and between dietary styles. In Table 3 the interrelationships between the vitamin B 6 status indicators are presented. PLP was significantly correlated with basal EAST activity and EAST-AC, whereas EAST-AC was correlated with all other in­ dicators, especially basal EAST activity. The highest cor­ relation was found for the association of basal EAST activity with total EAST activity. In the bivariate analyses, no significant association was found between EAST activity (basal and total),

VOL. 9, NO. 3

o z

H-I

Z

TI

O

O m

2 o > z o o rr

>

Ü

TI

o

z

1390 140 17

1100 160 21

28 3.9

27 2.7

33 3.9 1320 160 22

0.1 0.1

1140 150 16

23 3.0

6 2.1

< 0.001 ns ns

< 0.001 ns

8 0.8 350 30 4

ns ns

13 4.1

< 0.001 ns

65 6.7 200 42.6

202 48.5

14 4.2

< 0.001 ns

Effect of dietary fiber on the vitamin B6 status among vegetarian and nonvegetarian elderly (Dutch nutrition surveillance system).

To obtain more insight into the effect of dietary fiber on vitamin B6 status among elderly people, we studied dietary interrelationships as well as as...
733KB Sizes 0 Downloads 0 Views