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ORIGINAL ARTICLE
Year : 2013  |  Volume : 6  |  Issue : 1  |  Page : 60-65  

A comparative study of lipid profile and autonomic functions in vegetarian and non-vegetarian postmenopausal women


1 Department of Physiology, Padmashree Dr. D. Y. Patil Medical College, Hospital & Research Centre, Dr. D. Y. Patil Vidyapeeth, Pimpri, Pune, India
2 Department of Anaesthesiology, BMCH, Burdwan, West Bengal, India
3 Department of Gynaecology and Obstretics, BMCH, Burdwan, West Bengal, India
4 Department of Gynae and Obstretics, Swasthya Bhawan, Kolkata, West Bengal, India

Date of Web Publication14-Mar-2013

Correspondence Address:
Arunima Chaudhuri
Krishnasayar South, Borehat, Burdwan - 713102, West Bengal
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0975-2870.108645

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  Abstract 

Background: The prevalence of dyslipedaemia, autonomic dysfunction leading to cardiovascular diseases, increases with menopause and an ageing population. Autonomic dysfunction as measured by lower heart rate variability is an established risk factor for cardiac death. Diet and nutrition have been extensively investigated as risk factors for major cardiovascular diseases and are also linked to other cardiovascular risk factors. Objectives: To compare lipid profile and autonomic functions of postmenopausal women on vegetarian and non- vegetarian diet. Materials and Methods: 120 Postmenopausal women (menopausal duration and age-matched) without any gross systemic disease from an Industrial population were selected. Sixty women were on vegetarian diet and 60 on non-vegetarian diet. BMI and waist/hip ratios were calculated, lipid profile was analyzed, and autonomic function tests were carried out. A comparison was done between the two groups using Students t test. Pearson's correlation coefficient was calculated between the independent variable (lipid profile parameters) and the dependent variables (deep breath test, valsalva ratio, 30:15 ratio, OTT, IHG, CPT) to understand the effect of lipid profile on autonomic control of heart. Results : Significant increases in total cholesterol, triglyceride, LDL, cholesterol/HDL ratio were noticed in women on non-vegetarian diet. Results of autonomic function tests, i.e. valsalva ratio, deep breath test, 30: 15R-R intervals ratio, isometric hand grip test, cold pressor test, and orthostatic tolerance test were significantly worsened in postmenopausal women on non-vegetarian diet. Conclusion: Dietary factors may be an important cause of alteration of lipid metabolism. Increased cholesterol decreases heart rate variability and increased LDL cholesterol decreases baroreceptor sensitivity thereby worsening autonomic functions in postmenopausal women.

Keywords: Diet, lipid profile, menopause and autonomic functions


How to cite this article:
Chaudhuri A, Borade NG, Bandopadhyay AK, Hazra SK, Saha S, Mondol S. A comparative study of lipid profile and autonomic functions in vegetarian and non-vegetarian postmenopausal women. Med J DY Patil Univ 2013;6:60-5

How to cite this URL:
Chaudhuri A, Borade NG, Bandopadhyay AK, Hazra SK, Saha S, Mondol S. A comparative study of lipid profile and autonomic functions in vegetarian and non-vegetarian postmenopausal women. Med J DY Patil Univ [serial online] 2013 [cited 2020 Aug 4];6:60-5. Available from: http://www.mjdrdypu.org/text.asp?2013/6/1/60/108645


  Introduction Top


Cardiovascular diseases (CVD) are growing contributors to global disease burdens, with epidemics of CVD advancing across many regions of the world which are experiencing a rapid health transition. Diet and nutrition have been extensively investigated as risk factors for major CVD like coronary heart disease (CHD) and stroke and are also linked to other cardiovascular risk factors like diabetes, high blood pressure, and obesity. [1],[2],[3]

In India, 1.5 million deaths due to CVD are reported every year. Compared with all other countries, India suffers the highest loss in potentially productive years of life due to death from CVD in people aged between 35 and 64 years. [1],[2],[3]

There is a marked rise in prevalence of CHD in females after the age of 40 years.

The prevalence of CVD is reported to be two to three times higher in the urban population as compared to the rural. CHD is expected to be the single most important cause of morbidity and mortality in India by the year 2015. [1],[2],[3]

Reduced heart rate variability (HRV), a measure of cardiac autonomic dysfunction, is a risk factor for coronary artery disease (CAD). Diet can influence HRV, but this association may be confounded by genetic and environmental factors. Autonomic dysfunction as measured by a lower HRV is an established risk factor for cardiac death. [1]

Menopause may be associated with decreased HRV and autonomic dysfunction, which is due to reduced parasympathetic or increased sympathetic outflow to the heart, and acute myocardial infarction may be accompanied by decreased HRV. [4],[5] Disorders of autonomic nervous system (ANS) may result from pathology of either the CNS or the peripheral nervous system. Signs and symptoms may result from interruption of the afferent limb, CNS processing centers, or efferent limb of the reflex arc controlling autonomic responses. [6],[7],[8]

Loss of estrogen in menopause causes dyslipidemia. Hypercholesterolemia has been proved to be associated with a decreased 24-hour HRV. Baroreceptor sensitivity is negatively correlated with low-density lipoprotein (LDL) cholesterol levels. [6],[7],[8]

Menopause may result in endothelial dysfunction and increase in body weight and type 2 diabetes, which causes an increase in sympathetic activation. [5],[6],[7],[8] Decreased baroreflex sensitivity also appears with increasing body mass.

At the time of menopause, a woman must re-adjust her life from one that has been physiologically stimulated by estrogen and progesterone production to one devoid of these hormones (6).

The altered sympathovagal activity has an additional adverse effect on health profile. As life expectancy increases, women in general experience a longer life after menopause. The association of menopause and increased risk of health hazard is well known. Failure to recognize these can increase morbidity and mortality. [8],[9],[10],[11]

As populations become more westernized, dietary composition changes to include more saturated fat and less fiber. The present study was undertaken to evaluate relation of diet on autonomic functions in postmenopausal women so that early lifestyle modification may improve the quality of life. [1],[4],[5]

It is increasingly recognized that regular consumption of fish or dietary supplementation of fish oils rich in long-chain omega-3 polyunsaturated fatty acids (n-3 PUFAs) lowers the risk of CHD and protects against sudden cardiac death. Vegetarians have lower platelet and plasma concentrations of n-23 PUFAs than do omnivores. Alpha Linolic acid (ALA) from vegetable oils (canola and linseed) has a beneficial effect on n-23 PUFA concentrations of platelet phospholipids and plasma lipids. [11],[12]

The need to prioritize selected foods and overall dietary patterns rather than only individual nutrients, the relevance of carbohydrate and fat quality as well as quantity, the effects and policy implications of sodium consumption, the importance of energy balance, and the role of dietary supplements represent several key findings of interest. [11],[12]


  Materials and Methods Top


Materials

A total of 120 postmenopausal women without any gross systemic disease were selected for the study. Sixty postmenopausal women who were on vegetarian diet (had never consumed non-vegetarian food lifelong) were taken as the study group and 60 on non-vegetarian diet as the control (they were used to non-vegetarian diet lifelong).

Inclusion Criteria

Women with history of amenorrhea for consecutive 12 months or more were considered as menopausal. The study and control group were age matched.

Exclusion Criteria

Patients with tachycardia, cardiac arrhythmias, hypertension, diabetes, ischemic heart disease, retinopathy, nephropathy, and any other chronic disease or associated factors (drugs) that may affect the autonomic reflexes were excluded from the study. Subjects on hormone replacement therapy were also excluded. None of the subjects were on any daily exercise regime or practicing yoga. Subjects whose fasting blood samples were more than normal range were excluded from the study.

Methods

Approval from the Ethical committee was taken before conduction of this cross-sectional study. On first appointment, particulars of the subject, chief complaints, personal history, family history, history of past illness, treatment history, and dietary history of the subjects were carefully recorded. General physical examinations were done and written consent taken. Pre-test instructions were given to avoid consumption of any drugs that may alter the autonomic function 48 hours prior to the test. The subjects were advised for a good restful sleep. On the day of the test, no cigarette, nicotine, coffee, or drugs were permitted. Fasting blood samples were drawn for assessment of lipid profile, and fasting sugar analyzed to exclude diabetics, followed by Anthropometric measurements. Basal heart rate and blood pressure were recorded, followed by the autonomic function tests. The tests were performed at controlled room temperature in the morning between 10 and 11 am.

Patient preparation

The patients were made to wear loose gowns, and tight under clothing, metallic objects like rings, watches, etc. were removed.

Anthropometry

Body Weight


A digital weighing scale was used to measure body weight with an accuracy of ± 100 gm. Subjects were weighed without their shoes.

Height

Standing body height was measured without shoes to the nearest 0.5 cm with the use of height stand with shoulders in relaxed position and arms hanging freely.

Body Mass Index

BMI was calculated as body weight in kilograms divided by square of body height in meters.

Waist/Hip Ratio

WHR of the subjects were measured. Waist circumference was measured at the level of umbilicus and hip circumference at the fullest point around buttocks. Waist circumference was divided by hip circumference in order to calculate the WHR.

Lipid Profile

Early morning venous samples were collected in plain bulbs from the subjects for analysis of lipid profile following a

12 hour overnight fasting. Samples were collected, centrifuged, and analyzed on the same day.

Determination of Resting Heart Rate (RHR)

Polyrite is an electrical device with multi-channel physiograph recording. It has a built in electrocardiograph (ECG) channel for recording electrocardiogram.

Recording: Lead II of the ECG was selected for recording heart rate. The ECG tracings were screened for any suspected pathological waveform configuration. [13]

Autonomic function Tests [13]

Tests Reflecting Cardiac Parasympathetic Damage


Heart rate response to postural change (30:15 ratio) (normal ≥ 1.04), heart rate variation during deep breathing (normal ≥ 15), heart rate response to valsalva maneuver (VR) (normal ≥ 1.21).

Tests Reflecting Sympathetic Damage

Blood pressure response to postural change (the fall in systolic pressure was used as the result of orthostatic tolerance test, OTT; abnormal: 30 mmHg or more), to sustained (isometric) hand-grip (the rise in diastolic blood pressure was calculated and taken as the result of IHG test. abnormal: 10 mmHg or less), and cold pressor test (the response of 15-20 mmHg minimum increase in systolic blood pressure and 10 mmHg minimum rise in diastolic blood pressure is considered as normal response to cold pressor test, CPT [14] ).

The resting time given to subjects in between two tests was 5 to 10 minutes.

Statistical Analysis

Mean and SD values of all parameters of both groups were arranged in tabular form and analyzed using unpaired Students t test. For all analysis probability values (P value) < 0.05* were considered as statistically significant and P values < 0.01** were considered as statistically highly significant. Pearson's correlation coefficient was calculated between the independent variable (lipid profile parameters) and the dependent variables (deep breath test, valsalva ratio, 30:15 ratio, OTT, IHG, CPT) to understand the effect of lipid profile on autonomic control of heart.


  Results Top


Significant increases in BMI, waist/hip ratio, resting pulse rate, systolic blood pressure, total cholesterol, triglyceride, LDL, cholesterol/HDL ratio were noticed in women on non-vegetarian diet. Results of autonomic function tests, i.e. valsalva ratio, deep breath test, 30: 15R-R intervals ratio, isometric hand grip test, cold pressor test, and orthostatic tolerance test were significantly worsened in postmenopausal women on non-vegetarian diet [shown in [Table 1] and [Table 2]. No significant difference was observed in menopausal duration between the two groups (Mean: Subjects on Vegetarian diet: 6.9 and Subjects on Non-Vegetarian diet: 6.7; P value: 0.512). [Table 3] shows that total cholesterol, triglyceride, LDL are negatively correlated with autonomic function tests except OTT, while HDL is positively correlated with autonomic function tests except OTT.
Table 1: The average values of pulse rate, blood pressure, bmi, waist/hip ratio, total cholesterol, TGL, HDL and LDL and cholesterol/HDL ratio of postmenopausal women on vegetarian & non-vegetarian autonomic functions

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Table 2: The average values of valsalva ratio, deep breath test, 30:15 R-R interval ratios, isometric hand grip test, OTT and cold pressure test of postmenopausal women on vegetarian & nonvegetarian autonomic functions

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Table 3: Total cholesterol, triglyceride, LDL are negatively correlated with autonomic function tests except OTT results, while HDL is positively correlated with autonomic function tests except OTT results

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  Discussion Top


The present study demonstrated that body weights were elevated with non-vegetarian diet in postmenopausal women. The increases of cardiac vagal activity and baroreflex sensitivity by vegetarian diets in postmenopausal women are inversely related to LDL-cholesterol levels. [4],[5],[6],[7] Hypercholesterolemia is known to cause a decrease in HRV. [4],[5],[6],[7]

Numerous studies show important and quantifiable benefits of the different components of vegetarian diets, namely the reduction of risk for many chronic diseases and the increase in longevity. An abundant consumption of vegetables, fruits, cereals, nuts, and legumes all have been independently related to a lower risk for several chronic degenerative diseases, such as ischemic heart disease, diabetes, and some cancers. [15]

Many studies have shown that a vegetarian diet can affect risk factors for CVD, which remains the number one cause of death in America. In a study comparing healthy postmenopausal vegetarian women with omnivores, the vegetarians had statistically lower systolic and diastolic blood pressure (BP), along with lower total cholesterol, LDL cholesterol, triglycerides, fasting blood sugar, and hemoglobin levels. Other research has found that people eating a low-calorie, low-protein vegan diet had lower systolic and diastolic BP than two other groups studied: endurance runners eating a Western diet and sedentary people eating a Western diet. Both the vegans and the endurance runners had lower levels of lipids, lipoproteins, glucose, insulin, C-reactive protein, and BP than did the sedentary Western diet group. A study of vegetarians aged 35 to 64 in Brazil also found that they had lower BP, total cholesterol, LDL, triglycerides, and glucose than did meat-eaters. [1],[15],[16],[17]

A long-term vegetarian diet is associated with markedly higher fasting plasma AA (ascorbic acid) concentrations and lower concentrations of TAG (total and lipid standardized), uric acid, and high-sensitivity C-reactive protein. Long-term vegetarians have a better antioxidant status and CHD risk profile than do apparently healthy omnivores. Plasma AA may act a useful marker of overall health status. [15],[16],[17]

Other research suggests that a Western dietary pattern substantially increases the risk of type 2 diabetes in men and may increase the risk in women. [18],[19] In addition, a 21-year study and follow-up found that "the rate of diabetes as an underlying cause of death in Adventists was only 45% of the rate for all U.S. whites." [20]

The ability of a vegetarian diet to reduce blood pressure has been documented numerous times. In fact, one study notes that scientific interest in this effect of a meat-free diet dates to the early decades of the 20th century. [21],[22]

A study of Seventh-day Adventists, a religious group that encourages abstinence from meat, alcohol, caffeine, and tobacco, found that they had lower systolic blood pressure in early adulthood, and that systolic BP increased less with age. The same was true of diastolic blood pressure. [22]

The increases of cardiac vagal activity and baroreflex sensitivity by vegetarian diets in postmenopausal women are inversely related to LDL-cholesterol levels. Hypercholesterolemia has been proved to be associated with a decreased 24-h HRV in men. [23],[24],[25],[26] Decreased HRV is a strong predictor of coronary mortality, [27] so the fact that raised serum LDL cholesterol concentrations increase the mortality from CAD might partially be due to an impaired autonomic balance. [25] Also, treatment with the lipid-lowering agent atorvastatin has been shown to increase in HRV level in hypercholesterolemic patients with or without CAD. [28],[29],[30] In addition, serum LDL cholesterol is oxidized by macrophages to become oxidized LDL, which has important atherogenic properties by increasing inflammatory response. [23] An increased inflammatory activity may also lead to poor prognosis in CAD by declining HRV levels. [28] In the Cholesterol and Recurrent (CARE) study, [26] the magnitude of the endothelium-dependent vasodilatation was significantly correlated with the percentage change in LDL cholesterol concentration after administration of pravastatin. Therefore, the impaired endothelium-dependent arterial dilatation in the vessel walls caused by higher lipid levels might also change the baroreflex capacity. [24],[25]


  Conclusion Top


Dietary factors may be an important cause of alteration of lipid metabolism. Increased cholesterol decreases heart rate variability and increased LDL cholesterol decreases baroreceptor sensitivity thereby worsening autonomic functions in postmenopausal women.

 
  References Top

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29.Kimura T, Matsumoto T, Akiyoshi M, Owa Y, Miyasaka N, Aso T, et al. Body fat and blood lipids in postmenopausal women are related to resting autonomic nervous system activity. Eur J Appl Physiol 2006;97:542-7.  Back to cited text no. 29
    
30.Pehlivanidis AN, Athyros VG, Demitriadis DS, Papageorgiou AA, Bouloukos VJ, Kontopoulos AG. Heart rate variability after long-term treatment with atorvastatin in hypercholesterolemic patients with or without coronary artery disease. Atherosclerosis 2001;157:463-9.  Back to cited text no. 30
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3]


This article has been cited by
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[Pubmed] | [DOI]



 

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