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European Journal of Clinical Nutrition (2007) 61, 77–82

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ORIGINAL ARTICLE

Changes in thiamin intake and blood levels in young, overweight/obese women following hypocaloric diets based on the increased relative consumption of cereals or vegetables RM Ortega1, P Andre´s2, AM Lo´pez-Sobaler1, E Rodrı´guez-Rodrı´guez1, A Aparicio1, LM Bermejo1, L Garcıá-Gonza´lez1 and B Basabe1 1

Departamento de Nutricioń, Facultad de Farmacia, Universidad Complutense, Madrid, Spain and 2Laboratorio de Tećnicas Instrumentales, Seccioń Departamental de Quı´mica Analı´tica, Facultad de Farmacia, Universidad Complutense, Madrid, Spain

Objective: To analyse the changes in thiamin intake and blood levels of young, overweight/obese women following slightly hypocaloric diets based on the increased relative consumption of foods whose intakes were most removed from the ideal: cereals and vegetables. Design: The women were randomly assigned to one of two slightly hypocaloric diets: diet V, in which the consumption of vegetables was increased, or diet C, in which the consumption of cereals (especially breakfast cereals) was increased. Subjects: The study subjects were 67 young women with a body mass index of 24–35 kg/m2. Interventions: Dietetic, anthropometrics and biochemical data were collected at the start of the study and again at 2 and 6 weeks. Results: The reduction in energy intake was similar in both groups. However, diet C subjects lost significantly more weight. Blood thiamin concentration was higher in group C women than in group V women at 2 and 6 weeks. Compared to initial values, group C subjects showed a higher blood thiamin level at 2 weeks. The highest blood thiamin levels seen in group C women may have been due to their greater thiamin intake, their higher thiamin dietetic density, and a higher thiamin/ carbohydrates ratio at both week 2 and 6 of the intervention period. Conclusions: Increasing the relative consumption of breakfast cereals within the context of a slightly hypocaloric diet can help in weight control and improve thiamine intake and blood levels. ˜ a via the Universidad-Empresa project 362/2003. Sponsorship: This work was financed by Kellogg Espan

European Journal of Clinical Nutrition (2007) 61, 77–82. doi:10.1038/sj.ejcn.1602476; published online 12 July 2006 Keywords: thiamin; overweight; obesity; cereals; vegetables; young women

Introduction Thiamin status is important in overweight/obese persons since this vitamin is involved in energy metabolism (Food and

Correspondence: Dr RM Ortega, Departamento de Nutricioń, Facultad de Farmacia, Universidad Complutense, 28040-Madrid, Spain. E-mail: [email protected] Guarantor: RM Ortega. Contributors: RMO, PA and AMLS have been involved in the study design and data analysis. ERR, AA and LMB participated in data collection and recording. ERR, AA, LMB, LGG and BB also contributed to the analysis of the data, and revision of the paper. Received 23 August 2005; revised 21 April 2006; accepted 22 May 2006; published online 12 July 2006

Agriculture Organization of the United Nations and World Health Organization, 2001). In addition, thiamin is essential for glucose oxidation and insulin production in the pancreatic beta-cells, and it may improve glucose tolerance (Bakker et al., 2000). Glucose tolerance problems are more common among overweight/obese persons (Bakker et al., 2000). Thiamin deficiency (as well as other nutrient deficiencies) can be more common among people worried about their weight who frequently embark on sporadic and poorly controlled diets (Manore, 2000; Neumark-Sztainer et al., 2004). One reason for a poor thiamin status may be longterm low dietary intakes associated with poor dietary choices or reduced energy intake (van der Beek et al., 1994). Some studies also show that thiamin status can be impaired in

Changes in blood thiamin levels by two dietetic interventions RM Ortega et al

78 obese persons (Patrini et al., 2004), especially if they suffer deficiencies in other nutrients (Turkki et al., 1992). The aim of the present work was to evaluate the thiamin intake and blood levels of overweight/obese women who were worried about their weight, and to analyse the changes in thiamin status provoked by two, slightly hypocaloric diets based on increasing the relative consumption of cereals or vegetables, and thus approximating their intake to recommended levels.

Materials and methods Study subjects The study subjects were 67 women aged 20–35 years (mean 27. 874.6). Most were university students. The subjects were enrolled through a public offer to take part in a study on ‘The assessment of nutritional status and improvement of weight control’. The study was publicized using posters, radio announcements and via publications directed towards young, female university students. Initially, all interested parties were interviewed by telephone to ensure that they met the inclusion criteria, which were: female sex, age 20–35 years, body mass index (BMI) 24–35 kg/m2, not having quitted smoking in the two previous months, to be free of all disease that might interfere with the results, such as diabetes, hyperthyroidism, metabolic disease, hypertriglyceridaemia, lactose or gluten intolerance (celiac disease) and food allergies etc., to not be currently involved in a weight loss program, to have not lost more than 4.5 kg in the 2 months before the study, to have not lost or gained more than 3 kg between the first interview and the start of the study, to have a regular menstrual cycle, to take no more than two alcoholic drinks per day, and to be neither pregnant nor lactating. Those interested in taking part declared themselves to meet all inclusion criteria, were invited to the Department of Nutrition at the University Complutense de Madrid. Here, their weights and heights were recorded, and questionnaires were completed to collect personal, health and dietary information etc. All persons who were confirmed as meeting the inclusion requirements were informed of the aim of the study, of the clinical tests they would undergo, and of the number and type of interviews and testing to which they would be subject. According to the requirements of the Ethics Committee of the Faculty of Pharmacy, all subjects signed a witnessed form of consent to be included. The final number of aspirants was 193, but only 67 met all the inclusion criteria. In all, 57 women concluded the 6 week dietary intervention period.

Interventions The diets were designed to provide a mean of approximately 20% less than the theoretical energy requirements of the subjects. Theoretical energy expenditure was established by European Journal of Clinical Nutrition

taking into account the body weight, age and physical activity of all subjects (Ortega et al., 2003a), using equations proposed by the World Health Organization (WHO, 1985). Both diets were structured with the idea of approximating them to the theoretical ideal by increasing the relative consumption of either vegetables or cereals; earlier studies have shown that these foods are those with the greatest differences between their observed and recommended intakes (Ortega et al., 1996a, 1999b, 2000; Navia et al., 2003). Diet C. With this diet, the weight control measures were based on restricting the consumption of energy-rich foods and increasing the consumption of cereals. Breakfast cereals and cereal bars were particularly recommended (a minimum of three times/day) since, apart from carbohydrate, they also provide fibre, vitamins and minerals. However, the subjects were also advised to eat other cereals, for example, bread, rice and pasta etc. Diet V. With this diet, the weight control measures were based on restricting the consumption of energy-rich foods and increasing the intake of vegetables (minimum three times/day). The full characteristics of the diets followed and other methodological details are described elsewhere (Ortega et al., 2005).

Compliance to dietary rules Over the total intervention period (a total of 6 weeks), the subjects attended a weekly appointment to record anthropometric data and to discuss (and solve) any difficulties in following the diet assigned.

Methods The following data were collected from all subjects during the preintervention stage, and again at 2 and 6 weeks. Anthropometric information. Weight and height were determined using a Seca Alpha digital electronic balance (range 0. 1–150 kg) and a Harpenden digital stadiometer (range 70– 205 cm), respectively. For both measurements, subjects were barefoot and wore only underwear. All data were collected at the Department of Nutrition by trained personnel following norms set out by the WHO (1995). The BMI was calculated as weight (kg)/height2 (m2). Dietetic study. A ‘food and drink record’ was used to register all intakes (both at home and away) for 3 days, including a Sunday (Ortega et al., 2003b). Subjects were instructed to record the weights consumed if possible, and household measurements (spoonfuls, cups etc.) if not. The aim was to have as true a record as possible; subjects were asked to record all intakes, even though they broke the ‘rules’ of their diet.


79 The energy and nutrient contents of these foods were then calculated using food composition tables (Department of Nutrition, 2004a). The values obtained were compared to those recommended (Department of Nutrition, 2004b) to determine the adequacy of the diets. Special attention was paid to the intake of energy, macronutrients and thiamin. DIAL software was used to process all data (Ortega et al., 2004). Blood biochemical study. Thiamin was determined in whole blood by the HPLC fluorimetric thiochrome method with precolumn derivatization via the addition of a cyanogen bromide solution (Tallaksen et al., 1991). The column used was a Supelcosil NH2 column (250 4.6 mm LD) (Symta, Madrid, Spain). The mobile phase for the elution of thiamin consisted of acetonitrile and phosphate buffer (85 mM, pH 7.5) in the ratio 90:10 (v/v). The fluorescence detector used was a model F1050 (excitation wavelength at 375 nm; emission measured at 450 nm) with a 4290 Varian integrator (Varian Analytical Instruments, Sugar Land, TX, USA). This was attached to a L 6200 Merck Hitachi intelligent pump (Hitachi Ltd, Tokyo, Japan). The centrifuge used was a Beckman J2-21 (Beckman Instruments Inc., Palo Alto, CA, USA). The thiamin hydrochloride used was purchased from Sigma (St Louis, MO, USA); cyanogen bromide (97%) was obtained from Aldrich (Steinheim, Germany). All other reagents were from Merck (Darmstad, Germany) (CV ¼ 3.4%). Statistical analysis. Means and standard deviations (s.d.) were calculated for all variables. Repeated-measures one-way ANOVA was used to analyse the change in variables over time in each diet group (preintervention data, results at 2 weeks and results at 6 weeks), followed by the Newman– Keuls test for multiple comparisons. The comparison of

group C and group V results was performed using the Student’s t-test (or the Mann–Whitney test if the distribution of results was not homogeneous). Linear correlation coefficients were calculated using the Pearson test. Comparisons between proportions were performed using the w2-test. All calculations were made using RSIGMA BABEL Software (Horus Hardward, Madrid). Significance was set at Po0.05.

Results During the dietetic intervention, group C subjects showed an increased intake of cereals and group V subjects showed an increased intake of vegetables, both at 2 and 6 weeks. The intake of fruits increased while that of pastries decreased in both groups; this was seen at both analysis times. The consumption of meat, fish and eggs also fell at two weeks with the C diet, and was lower at 6 weeks with both diets (Figure 1). Energy intake was also lower with both diets at weeks 2 and 6 (Table 1) – a consequence of the reduction in protein and fat intake (in both phases of the intervention) and a reduction in the consumption of carbohydrates with diet V at week 2 (Table 1). Even though the reduction in energy intake was similar in both groups, group C subjects lost significantly more weight (Table 1). Thiamin intake, the contribution of this intake towards the coverage of recommended levels, and the thiamin/100 g carbohydrates ratio increased with diet C at week 2 and 6. The thiamin dietary density and index of nutritional quality (INQ) for this vitamin (thiamin density/density recommended) improved with both diets at both analysis points (Table 2). Blood thiamin concentrations were higher among group C subjects at 2 weeks, and the percentage of women with blood

Figure 1 Consumption of different food groups. Diet V and C: hypocaloric diets in which the consumption of vegetables (V) or cereals (especially breakfast cereals) (C) was increased. Significative differences (Po0.05): (a) difference between preintervention and 2 week data, (b) difference between preintervention and 6 week data, (c) difference between 2 and 6 week data, (ANOVA and Newmal–Keuls post-test). (d) Difference between diets C and V (2 weeks), (e) difference between diets C and V (6 weeks) (t-test or Mann–Whitney test).

European Journal of Clinical Nutrition


80 Table 1 Mean changes in anthropometric and dietetic variables over the dietary intervention period (X7s.d.) Preintervention data Diet C

Diet V

Diet C

Diet V

Diet C

36

31

32

30

28

29

73.377.7 161.875.0 28.072.8

77.8710.9 164.875.9 d* 28.673.6

Weight loss since start (kg) Dietary data Energy (kJ/day) Proteins (g/day) Lipids (g/day) Carbohydrates (g/day)

Results at 6 weeks

Diet V Number (n) Anthropometrics data Weight (kg) Height (cm) BMI (kg/m2)

Results at 2 weeks

72.378.1 161.875.0 27.672.8

75.6710.6 164.976.0 d* 27.473.5

0.970.6

879072226 80.5721.3 104.5733.7 196.0752.3

991572113 d* 94.2723.9 d* 119.9737.5 212.0750.4

1.570.9 d**

65457959 a** 68.3712.8 a** 65.1714.1 a** 159.9731.1 a**

660471185 a** 69.7713.8 a** 48.0716.8 a**d*** 201.6736.4 d***

70.177.3 161.775.3 26.872.6 2.071.3 c***

663971144 b** 64.8712.3 b** 58.3719.8 b** 183.2734.9 c*

74.0710.9 164.675.8 27.373.6 2.871.4 c***d*

672871174 b** 69.9711.4 b** 51.0716.2 b** 202.8738.3 d*

Abbreviations: ANOVA, analysis of variance; BMI, body mass index. Diet V and C: hypocaloric diets in which the consumption of vegetables (V) or cereals (especially breakfast cereals) (C) was increased, *Po0.05; **Po0.01; ***Po0.001. a: difference between preintervention and 2 week data, b: difference between preintervention and 6 week data, c: difference between 2 and 6 week data, (ANOVA and Newmal–Keuls post-test) d: difference between diets C and V (t-test or Mann–Whitney test).

Table 2 Changes in thiamine intake and blood levels over the dietary intervention period (X7s.d.) Preintervention data

Dietary data (n) Thiamin intake (mg/day) Thiamin density (mg/MJ) Coverage of RI (%) Thiamin intakesoRI (%) INQ INQo1 (%) Thiamin/carbohydrates (mg/100 g) Blood data (n) Thiamin (nmol/l) o150 nmol/l (%)

Results at 2 weeks

Results at 6 weeks

Diet V

Diet C

Diet V

Diet C

Diet V

Diet C

36 1.9170.72 0.2270.07 171.6762.1 11.1 2.0270.73 2.78 1.0370.48 34 183.8736.2 22.2

31 2.1770.58 0.2370.07 192.4750.5 0 d* 2.0870.73 6.45 1.0670.33 31 184.1736.9 19.4

32 1.7270.34 0.2670.04 a* 156.8730.5 0 a* 2.3470.38 a* 0 1.1070.21 30 190.2738.8 10

29 2.9970.60 a**d*** 0.4670.08 a**d*** 272.9755.6 a**d*** 0 4.0770.86 a**d*** 0 1.4970.23 a**d*** 30 217.5740.0 a**d** 3.23 a*

28 1.9570.63 0.3070.08 b** 182.7758.3 0 b* 2.5470.66 b** 0 1.0970.34 27 169.9740.0 29.6

29 3.0170.59 b**d*** 0.4570.07 b**d*** 275.0754.4 b**d*** 0 4.0470.81 b**d*** 0 1.5070.25 b**d*** 27 200.9743.5 d** 3.70 b*d**

Abbreviations: ANOVA, analysis of variance; BMI, body mass index; INQ, index of nutritional quality. Diet V and C: hypocaloric diets in which the consumption of vegetables (V) or cereals (especially breakfast cereals) (C) was increased, RI: recommended intake, Thiamin density: intake/energy, INQ: Index of nutritional quality (Thiamin density/density recommended). *Po0.05; **Po0.01; ***Po0.001. a: difference between preintervention and 2 week data, b: difference between preintervention and 6 week data, (ANOVA and Newmal–Keuls post-test), d: Difference between diets C and V (t-test or Mann–Whitney test).

thiamin levels o150 nmol/l was reduced significantly in this group both at weeks 2 and 6 (Table 2). The percentage of women who experienced a blood thiamin increase of X2.22 nmol/l (P50) was greater among those in group C (70.4% compared to 28% among V subjects) (Po0.001).

Discussion The initial intake of meat þ fish þ eggs was higher than that recommended in both groups (Ortega et al., 1999b, 2000, 2005; FIAB, 2004), while that of cereals, vegetables and fruits European Journal of Clinical Nutrition

was lower (Figure 1). Similar results have been reported in other studies (Ortega et al., 2000, 2005; Navia et al., 2003). This justifies the designs of the two slightly hypocaloric intervention diets, which were based on approximating the intakes of cereals or vegetables to the theoretical ideal. In addition, some authors (Stamler and Dolecek, 1997) report the achievement of weight loss through the relatively increased consumption of low-fat dairy products, breads and cereals, fruit and vegetables. These informations led us to planning both dietetic interventions (diet C and diet V). The results obtained in the present study show that the goals set out were attained and that the consumption of cereals or vegetables did come closer to the theoretical ideal (Figure 1).


81 The initial dietetic and anthropometric results were similar to those obtained for other groups of overweight women (Ortega et al., 1996b, 2000, 2005; Navia et al., 2003) (Figure 1, Table 1). Despite the decrease in energy intake being similar for both diets, groups C subjects lost significantly more weight (Table 1). This is probably due to the differences between diet C and V: diet C has more carbohydrates and less fat (Table 1) (Stamler and Dolecek, 1997; Ortega and Andre´s, 1998; Ortega et al., 1999a). Alternatively, this may be due to the initial difference between the observed and recommended intakes which was greater for cereals than for vegetables (Ortega et al., 1999b, 2000, 2005; FIAB, 2004). Other authors (Albertson et al., 2003) have reported that being overweight/ obese is significantly less common among subjects with a higher intake of breakfast cereals (upper tertile of cereal consumption). The blood thiamin concentrations detected were similar to those reported in other studies (Botticher and Botticher, 1987; Tallaksen et al., 1991) (Table 2). By week 2 they had increased significantly among group C subjects. In addition, blood thiamin was higher in C subjects than in V subjects at weeks 2 and 6. This modification might be due to the greater thiamin intake of group C women, their greater thiamin density, the improved coverage of its recommended intake, and better INQ and thiamin/100 g carbohydrates ratio (Table 2). At 6 weeks, when thiamin intake was increased by 1.2 mg/day or more, the blood thiamin concentration was significantly higher (29.6759.8 nmol/l) than the observed when the increase in thiamin was o1.2 mg/day (4.66741.69 nmol/l). In addition, the increase in the thiamin/100 g carbohydrates ratio to over 1.3 mg/100 g was associated with a significant increase in blood thiamin levels (17.6749.2 nmol/l compared to 10.2744.0 nmol/l when this ratio was o1.3 mg/100 g). Correlations were also found between the increase in blood thiamin levels at week 6 (compared to the initial levels) and an increase in the dietary thiamin density (r ¼ 0.308) and the INQ (r ¼ 0.336). It would appear that breakfast cereals contribute significantly to the mean daily intakes of several micronutrients (particularly thiamin) because of their addition to these foods (Subar et al., 1998; Preziosi et al., 1999; Galvin et al., 2003; Gibson, 2003). Several authors report a correlation between thiamin status and cereal consumption (Preziosi et al., 1999; Galvin et al., 2003). This might explain the better thiamin status of group C subjects (Table 2). Indeed, as cereal consumption increased over the intervention period, so did thiamin intake (r ¼ 0.286), as well as the contribution of this intake to the coverage of recommended thiamin levels (r ¼ 0.264). Several studies report breakfast cereals to be one of the major sources of thiamin for some people (Subar et al., 1998; Preziosi et al., 1999; Galvin et al., 2003; Gibson, 2003). In the present study, a correlation was found between initial thiamin intake and the intake of cereals at the start of the

study (r ¼ 0.260), at week 2 (r ¼ 0.706) and at week 6 (r ¼ 0.509). Special attention should be paid to the micronutrient status of those who embark on a weight control intervention since the danger exists that their intake may suffer (Manore, 2000; Pachocka and Klosiewicz-Latoszek, 2002; NeumarkSztainer et al., 2004). Pachocka and Klosiewicz-Latoszek (2002) indicate that following a low-energy diet (about 1000 kcal/day) hinders the correct intake of a number of vitamins. They also report that among the women of their study, the lowest intakes were those of thiamin (82.8% of recommended dietary allowance). As thiamin takes part in energy metabolism (Food and Agriculture Organization of the United Nations and World Health Organization, 2001) it might be important that a satisfactory thiamin status be maintained in people who are trying to lose weight. Muroyama et al. (2003) indicate that a mixture of thiamin, arginine, caffeine and citric acid is effective in reducing adipose tissue mass as well as improving disorders in lipid metabolism. Although more research is needed in this area, it would seem clear that people who wish to lose weight would do well to avoid thiamin deficiencies. Effective weight loss measures are vital in the fight against obesity, but imbalanced diets that could lead to micronutrient deficiencies should be avoided. Neumark-Sztainer et al. (2004) report that adolescent girls who engage in unhealthy weight-control behaviour are at increased risk of dietary inadequacy. In their work, such subjects had significantly lower intakes of fruits, vegetables and grains than did girls who followed healthy weight-control patterns. The present work suggests that diet C is associated with greater weight loss than diet V (Table 1), and that it leads to a greater increase in thiamin intake and blood thiamin levels (Table 2). Increasing the relative intake of breakfast cereals in the context of a slightly hypocaloric diet may therefore help control weight while improving thiamin status. The status with respect to other micronutrients might also be improved.

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