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Revista Colombia Médica, Vol. 41, No. 3, 2010, pp. 224-234 Effect of interventions with ingestion of legumes and/or supervised exercise on the lipid profile of young, healthy sedentary women* Efecto de las intervenciones con ingesta de leguminosas y/o ejercicio supervisado sobre el perfil lipídico de mujeres jóvenes, sanas y sedentarias Luis F. Fajardo, MD,
MSc1, Dora G. Castellanos Fisiot, MgBiol1, Myriam
Chinchilla (qpd) Nutr, MgBiol1, * Research funded by the Office of Research
Promotion of the Academic Vice Rectory at Pontificia Universidad Javeriana,
Bogotá, DC, Colombia. Received
for publication Marach 23, 2009 Code Number: rc10033 SUMMARY Objective: To
contribute to the knowledge of some aspects of the Healthy Life Style by
studying the effects of including legumes in the diet and exercise at two
intensity
levels, along with the lipid profile of young sedentary women living at 2640
meters above sea level. Keywords: Healthy eating; Lipid profile; Exercise level; Legume intake. RESUMEN Objetivo: Contribuir
al conocimiento de algunos aspectos prácticos para llevar a cabo una
alimentación y estilo de vida saludable, mediante el estudio de los
efectos en el perfil lipídico de la inclusión de leguminosas
(fríjol, lenteja y garbanzos) en la dieta de mujeres sanas pero sedentarias,
acompañada de ejercicio con dos niveles de intensidad, moderada y
alta, efectuados a una altura de 2,640 metros sobre el nivel del mar (msnm) Palabras clave: Alimentación saludable; Dieta; Perfil lipídico; Intensidad de ejercicio; Consumo de leguminosas. The World Health Organization (WHO) holds that a healthy diet and adequate physical activity are main factors in the promotion and maintenance of good health throughout the whole life cycle1. In Colombia, this recommendation is adopted by the National Plan for Public Health, which among its central issues includes improving the health status of the population and avoiding the progress and occurrence of adverse outcomes in the population on the risk of becoming ill2. The National Policy on Food Safety, specifically announces as one of its objectives «To promote healthy habits and life styles that permit improving the population’s state of health and nutrition, and preventing the appearance of diet-associated illnesses»3. In spite of the urgency expressed by the organizations mentioned, the operational definitions that may lead to the quick adoption of a healthy diet and adequate physical exercise practiced regularly are scarce. In this sense, WHO recommendations can be classified as restrictive recommendations (those that begin by «limiting») like limiting the energy intake from fats, limiting sugar and salt intake, etc., and promotional recommendations like increasing intake of fruits and vegetables, legumes, grains, and dry fruits. With respect to physical activity, it is recommended that people keep physically active during their whole lives with at least 30 minutes of moderate intensity regular activity on an almost daily basis4. There are many combinations of dietary intervention, different from the restrictive ones, related to achieving healthy eating. The recommendation of increasing the intake of fruits and vegetables, legumes, grains, and dry fruit is very general and does not specify value of the increase, 5%, 10%, or 20%, or if all have to be increased at the same time, or if it suffices with only increasing any or some of these. The publication of the «Steps to Better Health» food pyramid in the United States offers indications on the minimum amounts, according to eating habits of North Americans, for whom legumes are recommended in portions much lower than those usually consumed in Colombia5. Likewise, aerobic exercise is one of the therapeutic focuses related to life style and it is recommended to improve lipid and lipoprotein levels in all individuals, including those with cardiovascular problems. However, except for the general recommendation of almost daily engaging in moderate intensity exercise lasting at least 30 minutes, there is no specification of what is the desirable level of intervention in public health. There is information available on the positive effect of the intake of legumes and dry whole grains on the lipid profile and glycemia levels, both in healthy and ill individuals6-10. There is also evidence of the beneficial effect of exercise, although random tests have yielded conflictive results, perhaps due to differences at the base line, characteristics of the exercise program, and duration of the intervention11,12. With the purpose of contributing to the knowledge of some practical aspects to engaging in healthy eating and life style, we present the results of the effects on the lipid profile by including legumes (beans, lentils, and chick peas) in the diet of healthy but sedentary women at the beginning of the study, accompanied by exercise at two intensity levels: moderate and high. The participants live at 2640 meters above sea level (masl). MATERIALS AND METHODS Design. The research was conducted in Bogotá (2640 masl) and it was a Clinical Intervention Study with four phases each lasting four weeks, which meant the participation of 4 groups of ~20 young sedentary women, who were subjected to exercise and food intake intervention, which consisted in including legumes for lunch three times per week. Assignment of participants to a particular group was not done randomly. The groups were the following: Group 1: Food intake and exercise intervention with a training workload equivalent to 45% of the peak oxygen consumption –maximum oxygen update –(VO2 peak) by the subject. Group 2: Food intake and exercise intervention with a training workload equivalent to 65% of (VO2 peak) by the subject. Group 3: No food intake intervention, exercise intervention with a training workload equivalent to 65% of (VO2 peak) by the subject. Group 4: Food intervention for 4 weeks, but without exercise intervention. Subjects. Through announcements on the Universidad Javeriana web page, female students were summoned to express their interest in participating in a clinical research related with food intake and physical activity. Four calls were made during four different weeks, corresponding to each phase of the research. Between 30 and 40 students expressed interest during each invitation. Assignment of the subjects to each intervention group was not random and it was done sequentially. The following inclusion criteria were considered: a) the subjects identified themselves as sedentary (without regular physical activity during the three months prior to the project, especially without physical activity lasting half an hour or more), b) during a physical activity evaluation prior to the intervention, the subjects were catalogued as sedentary by using the abbreviated version of the «International Physical Activity Questionnaire» (International Consensus Group for the Development of an International Physical Activity Questionnaire, WHO 1996), c) age 18 to 29 years, d) Body mass index <28, e) fitness to practice physical exercise and consume legumes evaluated through physical exam and history carried out by a physician. The exclusion criteria considered: Abnormal base line lipid profile, missing two or more exercise sessions or legume intakes. Of the students expressing interest, we selected the first 25 students who completed an interview with a nutritionist, a medical exam, and the international physical activity questionnaire (IPAQ). Of these, 23 were included in the study and 2 remained on standby. In total, 89 young women were included ranging from 18 to 30 years of age, university students at Pontifica Universidad Javeriana in Bogotá according to calculation of the sample: n [n =2S2/D2 F(a-b)] of 23 individuals per group to detect a difference of 2.2 mg/dl HDL, after 4 weeks of intervention, assuming a standard deviation of 2.7 mg/dl, and a 0.05% significance level one tail and power of 80%. one tail and power of. The participants were informed on the nature of the study and accepted to participate, signing an informed consent according to guidelines by the Research Committee at Pontificia Universidad Javeriana. All the subjects were in good health and presented no contraindication for exercise and ingestion of prescribed foods according to the medical exam performed on each subject. Food-Intake Intervention. For food-intake intervention, the subjects were prescribed lunch including legumes as low glycemic level food (beans, lentils, or chick peas), in amounts that would provide 13% of the daily energy intake. The lunch was calculated to account for 30% of the daily energy intake. This lunch was offered between 12 noon and 1 pm, 3 days per week during the 4 weeks of the intervention for groups 1, 2, and 4. For the dietary prescription, we kept in mind the usual values of energy ingestion and other nutrients, along with the feeding characteristics of each individual, obtained through a detailed dietary assessment. The lunch offered included the following foods: red beans, lentils, or chick peas (130-140 g), cooked white rice (70 g), fruit (80 g), raw or cooked vegetable (75 g) and an unsweetened beverage or natural lemonade (250 ml). The subjects were instructed to always consume the amount of legumes offered and the other foods making up the lunch ad libitum. During each of the days of intervention (three days per week for 4 weeks) each subject recorded the weight of the food portions consumed during the day. To comply with this activity, they were furnished a weighing scale and a measuring cup. Exercise intervention. The exercise prescription for the intervention was done by first determining the VO2 peak for each individual through ergospirometry with a Metapeak III® ergospirometer and an exercise protocol with increasing load on an Ergoline® cycloergometer, according to parameters established by Astrand and Wasserman13. Rest for 3 minutes on the bike to stabilize the parameters measured before starting the ergospirometry; Warm up by pedaling for 3 minutes at minimum power (15 watts); during this stage, each subject had to pedal at a constant rhythm between 60 and 70 revolutions per minute (rpm); the test included power increases of 15 watts every 3 minutes until reaching a respiratory coefficient of 1.15 or more, or • VO2 Plateau, in spite of the increased exercise load or •not being able to keep pedaling at the same rate of frequency. Group 1 was prescribed 30 minutes of exercise, 3 days per week with cardiac frequency equivalent to 45% of VO2 peak. Groups 2 and 3 were prescribed 30 minutes of exercise 3 days per week with cardiac frequency equivalent to 65% of VO2 peak. The participants in the study were instructed to do the exercise on the athletic field at Universidad Javeriana or at the same university’s Sports Center. In both situations, the participants were accompanied by a trained physical therapist. The subjects were free to do the exercise at their convenience between 9 am and 3 pm. During each programmed exercise session, each participant wore a cardiac frequency monitor (Timex Iron Man® or Polar S810®) capable of storing the time at which the subject reached and maintained the target cardiac frequency; this time was denominated time in zone. The study also stored the average cardiac frequency obtained over the time each exercise session was developed. Ideally, the time in zone and the average cardiac frequency during the activity should coincide with the time prescribed and the target cardiac frequency prescribed. During the programmed exercise sessions, the subjects were also asked for their perception of effort by using the Borg scale. Determination of lipoproteins. Blood samples were taken from the antecubital vein during the early morning hours after 12-hour fasting. Total cholesterol and triglyceride concentrations were analyzed via colorimetric enzyme assays (Serapak-Bayer). HDL cholesterol (HDL) was determine don the supernatant by centrifugation, post precipitation (chylomicrons, VLDL cholesterol (VLDL) and LDL cholesterol) with phosphotungstic acid and magnesium ions (Serapak-Bayer). LDL cholesterol and VLDL cholesterol levels were calculated by using the Friedwald formula when the samples did not have triglycerides greater than 400 mg/dl14. The assessments were made on an RA 50 (Bayer) instrument at the Clinical Biochemistry Specialization Laboratory at Pontificia Universidad Javeriana in Bogotá DC, and to control instrument efficiency, we used known-concentration calibrators (SERA CHEK from BAYER Labs SA). Statistical analysis. The statistical analysis was aimed at determining the differences in serum biochemical parameter measurements prior to intervention and after two and four weeks of intervention for the 4 groups intervened. One-way and contrast variance analysis tests were run via the Bonferroni method to study the differences in biochemical parameter changes among the four intervention groups, and Student t tests were run and confidence interval at 95% (CI 95%) to determine the significance of the differences in the biochemical parameters measured at the base line and after four weeks of intervention. The Stata IC version 10 statistical package was used. RESULTS The study included 81 women (Table 1), ranging in age between 18 and 29 years; with an average age of 20.89 years (CI 95% 20.45-21.33) average weight of 54.52 kg. (CI 95% 53.19-55.84), average height of 1.58 m (CI 95% 1.56-1.59) and average Body Mass Index (BMI) of 21.78 (95% CI 21.33-22.23). The subjects programmed for the dietary intervention, groups 1, 2, and 4, during the days programmed had an intake of 14%, 16%, and 16% of the total daily energy as legumes, respectively, and energy intake was reduced by 15% in group 1 and by 22.6% in group 2 (in group 4 this parameter was not evaluated). Note that the food intake was not stimulated by the researchers, but was rather spontaneously given (Table 2). Exercise intervention was carried out with 61 participants in the following manner: Group 1 had 12 exercise sessions (sessions 3 days per week for 4 weeks), prescribed at an intensity of 45% of VO2 peak, and done at an average intensity of 47% of VO2 peak. Group 2 had 12 programmed sessions with intensity at 65% and effectively done at an average intensity of 63.3% of VO2 peak, and group 3 also had 12 programmed exercise sessions with an intensity at 65% of VO2 peak that were done at an average intensity of 60.2% of VO2 peak (Table 3). Lipid profile measurements were done prior to starting the intervention, at two weeks of intervention and after four weeks of intervention. Base line measurements were taken from 88 subjects, at two weeks in 87 individuals and after 4 weeks in 82 individuals. The result of the interventions on the lipid profile was evaluated through TC, LDL, HDL, and TAG serum measurements. For the 4 groups intervened, we calculated, in the four components of the lipid profile, the average of differences (δ) among the base line values and after four weeks of intervention (delta (δ) = base line value –value after four weeks of intervention). In Table 4 we show the ä changes occurring in the levels of the lipid profile parameters after 4 weeks of intervention (note that the positive values indicate diminishing of the serum level profile and the negative values indicate increased serum level). The statistical significance of the differences (δ) among the intervention groups was evaluated through one-way variance analysis of the δ for the 4 groups and following contrasts via the Bonferroni test (Table 5). We also studied the difference of the serum values at the base line and after four weeks of intervention and were compared through a Student t test. These data are presented in Table 6. Total cholesterol. It was observed that in the intervention group of «Exercise at 65% VO2 peak + legumes» the maximum reduction was obtained (greater size δ) for the TC value, and that this d was significantly different to that observed in the groups «Only exercise at 65% VO2 peak» (Bonferroni p=0.002) and «Only included legumes» (Bonferroni p = 0.001), (Tables 4 and 5). In the group of «Exercise at 65% VO2 peak + legumes» a decrease of serum TC was observed after four weeks of intervention, which was statistically significant for the t test (p=0.0048) (Table 6). To evaluate the possibility of a dosage response effect an ANOVA was run of the TC including the terms group and week, revealing a significant effect for the term Group (F=5.04, p=0.0021), but not for the term Week (F=0.29, p=0.7496), thus discarding a dosage response effect of the time of intervention. Upon analyzing group averages of the TC presented in Table 6, it can be observed that the base line values for the four intervention groups are within the normal limits; however, the base line of the intervention group of «Only exercise at 65% VO2 peak», revealed significantly lower figures than groups of «Exercise at 45% VO2 peak + legumes» and «Exercise at 65% VO2 peak + legumes» (one-way ANOVA F 4.74, p= 0.0042; Bonferroni contrast p=0.016 and 0.005). We have no definite explanation for these differences and they could be attributed to bias in the selection of the participants in this group, which should be kept in mind in the discussion and conclusions because reductions are more difficult when starting with low TC values. LDL cholesterol. The greatest value of δ LDL was observed for the group «Exercise at 65% VO2 peak + legumes», followed by the value obtained by the group «Exercise at 45% VO2 peak+ legumes» (Tables 4 and 5). These data reveal that the maximum reduction in LDL (greatest value of δ LDL) was obtained in the group «Exercise at 65% VO2 peak + legumes», this reduction merely being significantly greater than that observed in the group «Only inclusion of legumes». Likewise, the group «Exercise at 65% VO2 peak + legumes» also showed a significant reduction in average LDL, going from 101.1 mg/dl to 81.1 mg/dl (p=0.0001). The possibility of a dosage response effect was analyzed via an ANOVA of the LDL including the terms Group and Week. The ANOVA (LDL-Group-Week) was significant (F=5.23, p=0.0001), with the term Group also being significant (p<0.0001), but not so for the term week. HDL cholesterol. The most negative values for δ HDL in Table 4 (greater increases of HDL) were seen in the intervention groups «Exercise at 65% VO2 peak + legumes» and «Only exercise at 65% VO2 peak». In the group «Only inclusion of legumes» favorable HDL level changes were not observed. And in the group «Exercise at 45% VO2 peak+ legumes» HDL increase was lower than in the groups with greater intensity exercise. The comparison of HDL values at the base line and after 4 weeks of intervention demonstrated a significant increase for the groups «Exercise at 65% VO2 peak + legumes» (51.2 mg/dl to 57.6 mg/dl) and «Only exercise at 65% VO2 peak» (49.8 mg/dl to 55.9 mg/dl) (Table 6). The ANOVA (HDL-Group-Week) was not significant (F=1.12, p=0.3511). Triacylglycerols. As in the case of the other lipid profile components, the differences in TAG serum values on the base line and after intervention (δ TAG) in the intervention groups are shown in (Tables 4 and 5). The three intervention groups including exercise, revealed the greatest reduction of serum TAG levels (δ TAG), greatest in the groups of exercise with intensity greater than (65% VO2 peak). In the group of «Only inclusion of legumes» we observed a δ TAG = -8.4 (negative value), which indicates increased TAG levels post intervention. The TAG averages for the group «Exercise at 65% VO2 peak + legumes» (Table 6) show significant diminishing of serum level going from 86.2 mg/dl to 64.9 mg/dl, p=0.0001. The ANOVA analysis (TAG –Group –Week) showed the existence of an effect on TAG levels attributable to the Intervention Group (ANOVA F=2.60, p=0.05), but not an effect attributable to time of intervention in weeks. DISCUSSION The study considered young, sedentary women with life styles concordant with their condition as university students, living in Bogotá DC, at an altitude of 2,640 masl. The change in lipid profile was evaluated as an indication of the beneficial effect of four weeks of intervention with actions that could become part of a healthy life style. The four intervention groups in this work were thus: Exercise at 45% of VO2 peak (~ 4 METs –moderate-intensity exercise) plus inclusion of legumes in diet, Exercise at 65% of VO2 peak (~ 6 METs high-intensity exercise) plus inclusion of legumes in diet, Exercise at 65% of VO2 peak (~6 METs high-intensity exercise) without dietary intervention (time of exercise: 30 minutes three days per week), and finally, diet intake intervention including legumes without changes physical activity levels; may be seen as different implementation stadiums to accomplishing healthy feeding and life styles. The results shown in Tables 4 and 5 refer to the differences in the magnitude of change obtained through the interventions. In the group «Exercise at 65% of VO2 peak + inclusion of legumes in diet» significant statistical and physiological results were obtained. We obtained an average reduction in TC of 19.8 mg/dl, in LDL of 21.8 mg/dl, an increase in HDL of 6.2 mg/dl, and reduction in TAG of 20.7 mg/dl. In the group of exercise at 45% of VO2 peak (moderate intensity) plus inclusion of legumes changes obtained were in the expected direction, but at a lower magnitude and not statistically significant. The values were: a reduction of 7.3 mg/dl in TC, a reduction of 6.8 mg/dl in LDL, and an increase of 0.9 mg/dl in HDL. Strategies by the WHO to prevent chronic illnesses1 contemplate efforts to have people consume healthy diets and perform moderate physical activity; however, other authors15 alert on the difficulties of carrying out these interventions. Our results indicate that the combination legume intake (healthy diet) and high-intensity exercise is better than any of the other interventions; furthermore, there is a relationship between exercise intensity and the resulting changes in lipid profile. The current study was conducted at an altitude of 2,640 masl, and the effect of altitude on the physiology of exercise16 has been well established. Although with the information available, we cannot confirm or deny the influence of this parameter on the results, we do want to wish to direct attention on this fact given the important number of people living in the Andean high plains. Several studies have shown the relationship between exercise intensity and the effects on lipid profile11,17; however, few studies report altitude over the sea level where the exercise is done. It is possible that at the altitude in Bogotá, longer-lasting interventions may be warranted (months instead of weeks). Other studies examining the effect of exercise on TC or on LDL report diminishing of 4 and 5% with respect to the initial value and indicate that reductions greater than 2% already have positive effects with respect to reduction of cardiovascular risk11. The group with moderate-intensity exercise and diet intervention showed a tendency for diminished TC, LDL, and TAG; rather, the group with only exercise at 65% of VO2 peak did not reveal significant reduction of TC or LDL, instead the tendency during the four weeks of intervention was to increase-although not significantly. According to the results of this study, it would seem that to achieve changes in TC, LDL, and TAG parameters, some combination form of legume intake and exercise is needed. In the group of only dietary intervention, we did not observe the changes associated to the consumption of legumes as reported by other authors6-10. An explanation of this result may be the type of legumes used, given that in our case we used canned beans, lentils, and chick peas and in several of the articles cited only beans are consumed; however, the WHO recommends legumes in general. Similarly, it must be kept in mind that the current study was of short duration and the consumption of whole grains and legumes associated to fruits and vegetables for longer periods may be beneficial, as noted with the Mediterranean diet18. With respect to increased HDL (Table 6) with the type of intervention, significant increases were obtained in the three intervention groups that included exercise; with the greatest increase registered in the groups with exercise intensity at 65% of VO2 peak. These results agree with the literature, both in the level of increase as in the association between magnitude of change and exercise intensity11. As reported by other studies, TAG levels diminish with exercise and in our study we obtained a reduction of 20.7 and 19.6 mg/dl in the groups with exercise intensity at 65% of VO2 peak, without the existence of significant differences attributable to the inclusion of legumes in the dietary intake (Table 6). Bearing in mind the limitations of a non-random study with only four weeks of observation, the results suggest that greater benefit is obtained with a combination of high-intensity exercise (~6 METS) carried out for 30 minutes three times per week and the inclusion of legumes (beans, lentils, chick peas) in amounts representing 15% of the daily energy intake, judging such benefit as desirable changes in the lipid profile (Diminishing of TC, LDL, TAG and increase of HDL). Hence, it would be the most desirable combination among those studied. Conversely, by merely including legumes in the dietary intake at the level used and monitoring the lipid profile for 4 weeks, it was not possible to evidence any change in lipid profile, suggesting that the recommendation of «increasing legume consumption» should be carried out for more prolonged periods with intake of greater amounts, i.e., it should be more qualified. The intervention of only high-intensity exercise (~6 METS) had the effect of increasing HDL, as shown in other studies and diminished TAG (p = 0.06) was marginally observed. This study highlights the importance of the dietary intervention, which as with the group of «Exercise at 65% VO2 peak + legumes» in the current study could be measured by the dietary fiber provided by the legumes and the low-glycemic index of the carbohydrates supplied by these legumes. The intervention with moderate-intensity exercise (~4 METS) and legumes revealed changes in the expected direction, but these were not statistically significant. Although the effects of moderate- or low-intensity exercise upon lipid profile is still a motive for discussion19, the effects of the altitude where the study was conducted are still an issue of study. In conclusion, different interventions compatible with healthy dietary intake and life style behave differently as far as their effect on the change in the levels of the fractions of the lipid profile studied, and, consequently, the manner of implementing the recommendation to adopt a healthy diet and life style can bear implications on the final outcome. For the altitude in Bogotá and the age group studied, an intervention with healthy eating and high-intensity exercise for 30 minutes, three days per week produces effects on the lipid profile consistent with diminished risk of cardiovascular disease. Conflict of interest. None of the authors has conflicts of interest related to this study. REFERENCES
Copyright 2010 - Colombia Médica The following images related to this document are available:Photo images[rc10033t6.jpg] [rc10033t3.jpg] [rc10033t2.jpg] [rc10033t1.jpg] [rc10033t5.jpg] [rc10033t4.jpg] |
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