Association of potato and other starchy vegetable consumption with cardiovascular diseases risk factors in Iranian elderly men

Given the limited research on potato and other starchy vegetable consumption with cardiovascular diseases (CVD), we examined the association of potato and other starchy vegetable intakes in association with cardiovascular risk factors and inammatory biomarkers among elderly men. In this study, 357 elderly men were participated. Dietary intake was assessed using food a valid and reliable frequency questionnaires. Two separated groups were considered. 1. Potato, 2. Other Starchy vegetables including corn, squash, green pea, and green lima beans. CVD risk factors including HDL, LDL, FBS, TG, TC, Alkaline phosphatase, Fibrinogen, Insulin, IL-6, TNF-α, SGOT and SGPT were measured. and Chi-square tests were used for compression of quantitative and qualitative variables, respectively. Analysis of covariance (ANCOVA) was used to assess the distribution of nutrients and food groups among tertiles of potato and other starchy vegetable group which was adjusted for energy intake. ANCOVA was used to check the association between potato consumption and CVDs. Different models were used to show any signicant association including model 1 which was adjusted for age, sex, SES, BMI, and energy intake. Model 2 as a further adjusted model (model 1 plus smoking, and total dietary ber intake). Also, model 3 which was adjusted for model 2 plus supplements consumption and medication. odds SES, ber Model SPSS for statistical

Introduction green pea, and green lima beans can regulate postprandial glucose, insulin responses and therefore can be linked to metabolic diseases like diabetes and CVDs. Also, the long term high consumption of potato has been considered as one of the important risk factors for the development of CVDs. In contrast, foods with low glycemic index foods such as whole-grain-rich diet can reduce and even prevent the risk of metabolic diseases (21).
To the best of our knowledge, there is no study about the association of potato and cardiovascular diseases among elderly subjects. Therefore, this study designed and implemented to determine the association of potato and other starchy vegetable consumption with cardiovascular diseases (CVD) risk factors in Iranian elderly.

Methods
In this cross-sectional study, the sample was collected from ten health center from south of Tehran, Iran. We selected men by cluster random sampling from these health centers (March to August 2017). We included men more than 60 years old, which were not restricted to any particular diet. Men with a malignant disease like a tumor and those who had over or under-reported total energy intake were excluded from this study (>4200 or < 800 kcal/day) (22). For estimating sample size we considered high sensitive C-reactive protein as a main dependent variable, we set α = 0.05, β = 4% and effect size = 1.5. Based on high sensitive C-reactive protein, the sample size was estimated to be 313. Keeping in the view of over or under-reported total energy intake, we selected 365 individual. After evaluation 8 people were excluded due to over or under-reported total energy intake and the nal sample size was 357. Ethical approval for this protocol was given by the National Institute for Medical Research Development (Grant and Ethics Number: 965430).

Anthropometric assessment
All participants were assessed for anthropometric indices including weight, height, waist circumference (WC), and body mass index (BMI). We used calibrated digital scales (SECA 831, Germany) for body weight, we asked the participants that remove their heavy clothing and shoes before recording the body weight. Height was measured while participants stood against the wall in an upright position without shoes. WC was measured over light clothing from the narrowest part of the waist with no pressure on breathing. We measured the BMI from the following formula:

Dietary assessment
Skilled nutritionist interviewed people face to face in order to obtain the usual dietary intake from 168-items semi-quantitative food frequency questionnaire (FFQ). The reliability and validity of this questionnaire have been previously tested (23). On a daily, weekly or monthly basis the participants were directed to record food consumption, the reported quantities of food consumption were converted into gram. We used the latest version of NUTRITIONIST IV for Iranian foods to calculate the average of nutrition and energy intake (24).
Starchy vegetables including corn, squash, green pea, and green lima beans.

Biochemical assessment
To measure the blood biomarkers, a blood sample was taken from each subject after 12 hours of fasting. An ultrasensitive latexenhanced immunoturbidimetric assay (Randox Laboratory Ltd., Belfast, UK) was used to measure high-sensitive C-reactive protein (hs-CRP) concentration. Triglycerides (TG), lipid pro les including total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and serum concentrations for fasting blood sugar (FBS).
Enzyme-linked immunosorbent assay (ELISA) method (Boster Biological Technology, China) was used for determining the serum level of in ammatory biomarkers (IL-6 and TNF-a). Clauss clothing method was used to determine the rate of brinogen conversion into brin. Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) (25) and Quantitative Insulin-sensitivity Check Index (QUICKI) (26) were used to assess insulin resistance and insulin sensitivity, respectively.

Other variables assessments
In this study, blood pleasure (BP) was measured when participants were sitting comfortably for at least 10 minutes. The BP was recorded twice with at least 30-second gap between them, an average of both secondaries was considered as the nal BP. To assess socioeconomic status (SES), a reliable and validated questionnaire was used which was developed previously for determining the association between health outcomes and SES in Iran. The SES questionnaire included the number of family members, occupation, level of education, ownership of personal car and home, modern home appliances and the number of local and international trips throughout the last year. The SES score was calculated based on the total score for each participant.
Moreover, the participants were asked about using smoking, supplements, and medication.

Statistical analysis
Kolmogorov-Smirnov test was used to determine the normal distribution of all variables. Analysis of variance (One-way ANOVA) and Chi-square tests were used for compression of quantitative and qualitative variables, respectively. Analysis of covariance (ANCOVA) was used to assess the distribution of nutrients and food groups among tertiles of potato and other starchy vegetable group which was adjusted for energy intake. ANCOVA was used to check the association between potato consumption and CVDs. Different models were used to show any signi cant association including model 1 which was adjusted for age, sex, SES, BMI, and energy intake. Model 2 as a further adjusted model (model 1 plus smoking, and total dietary ber intake). Also, model 3 which was adjusted for model 2 plus supplements consumption and medication.
Binary logistic was used to determine the odds ratio and con dence interval of CVD risk factors. Model 1 was adjusted for age, sex, SES, BMI, and energy intake while Model 2 is a further adjusted model (model 1 plus fat intake, smoking, and total dietary ber intake). Model 3 was adjusted for model 2 plus supplements consumption and medication. SPSS version 16 used for statistical analysis and P < 0.05 considered as a signi cant value. Table 1 depicts that there was a signi cant association between age (P = 0.002), weight (P = 0.010) and WC (P < 0.0001) of participants with a medium and high level of potato consumption. The SES score was higher in low and high potato consumption groups (P = 0.002). In addition, age was greater in people who consumed lower other starchy vegetables (P < 0.0001). There was a signi cant association between SES score and consumption of other starchy vegetables (P < 0.0001). Table 2. Participants' energy intake was more in medium and high potato consumption groups (P < 0.0001). Furthermore, energy intake (P < 0.0001) and fat intake (P < 0.0001) were higher in people who consumed more other starchy vegetables. Protein intake (P = 0.004) and calcium level (P = 0.002) were greater in medium and high potato consumption groups. Further, ber intake was greater in participants who consumed more other starchy vegetables (P = 0.001). Moreover, participants in the higher tertile of potato consumption consumed higher amounts of vitamin B12 (P < 0.0001), vitamin A (P = 0.001), calcium intake (P = 0.002). Additionally, Vitamin B1 (P < 0.0001), vitamin B6 (P < 0.0001), vitamin B12 (P = 0.001), vitamin A (P < 0.0001), vitamin C (P < 0.0001), Iron (P < 0.0001), vegetables (P < 0.0001), grain (P < 0.0001) intake were higher among participants who consumed more other starchy vegetables.

Dietary intake of participants has shown in
Biochemical markers among different levels of potato and other starchy vegetable consumption are demonstrated in Table 3. FBS level was signi cantly higher among those participants who consumed more other starchy vegetable as compared to participants who consumed more potato. Furthermore, TC (P < 0.0001) and SGOT (P < 0.0001) level were signi cantly greater in participants who consumed more potato.
Odd ratio and 95% con dence intervals of cardiovascular risk factors among participants based on the different amount of the potato and other starchy vegetable consumption illustrated in Table 4

Discussion
In the current cross-sectional study, we observed a positive association between potato consumption and serum level of TG and HDL among elderly men. Furthermore, other starchy vegetable consumption was inversely associated with serum level of SGPT among elderly men.
To the best of our knowledge, this is the rst study designed to determine the association between CVD risk factors and potato and other starchy vegetable consumption in elderly men. We observed no evidence that potato consumption was associated with the risk of major CVD events or mortality from CVD.
Our ndings illustrated positive association with potato consumption and serum level of TG. Animal studies on rats reported reduced cholesterol and TG levels with potato diet for 3weeks (27,28). Similarly, epidemiological studies demonstrated decline in serum TG level with potato consumption (29). In the same way, our study showed the positive association of potato consumption with serum TG level.
A cross-sectional study among 4774 men and women subjects has been found a positive signi cant association between potato intake and insulin resistance (IR), diabetes type 2 and FBS serum level. Additionally, after adjustment to age, sex, physical activity, and dietary intake the association between FBS and diabetes type 2 with potato intake remained signi cant while between IR and potato intake disappeared (21). In this study, we failed to identify the relationship between potato consumption and diabetes type 2 and FBS, because the subjects we studied were only elderly men while their subjects were in both gender and the sample size for our study is smaller. Moreover comparatively our study has more adjusted viable such as age, sex, SES, BMI, fat intake, smoking, total dietary ber intake, supplements consumption, and medication. Another cross-sectional study among 357 elderly men found a positive association between DIL (Dietary Insulin Load) and serum level of FBS. The positive signi cant association observed between high DIL with FBS serum levels after adjustment to energy intake, marital status, socioeconomic status, smoking, disease status, anti-diabetic drugs, thyroid drugs, and heart disease drugs (30). Mentioned studies observed a positive association between DIL and FBS. It means that the long-term consumption of high insulin index foods caused β cell dysfunction and this situation subsequently caused IR and increased serum level of glucose (31).
This study showed a positive association of potato consumption with decrease serum level of HDL and increase serum level of TG, but we could not nd an association with other lipid pro les.
We observed noticeable increase in the mean of total cholesterol in highest versus lowest tertile of potato consumption. But based on our result there was high TC in participants who had a higher consumption of potato rather than low consumption of potato. Although this increase in cholesterol has no clinical signi cance.
However, we observed lower LDL-C serum level in participants who consumed more other starchy vegetable while higher LDL-C serum level observed in subjects who consumed higher potato. In our study, there were few subjects with TC more than 200 and a Page 6/12 high level of LDL-C for that's why we weren't able to consider the odds ratio of TC and LDL-C related to potato consumption. We found this association according to mean. The high plasma of HDL-C play a protective role for myocardial infarction and reduce coronary heart disease (32)(33)(34). The result of a cross-sectional study with 2045 among different race in both gender depicts the consumption of fried potatoes was over 75% across groups and was associated with higher odds dyslipidemia (high non-HDL cholesterol). All unhealthy foods measured were consumed more often by males as compared to females (35). Another crosssectional study (n = 12514) among men and women observed a positive association between potato consumption and low HDL-C level (36). Phosphorus content of other starchy vegetables has other favorable properties, as it slows digestion and absorption and thus lowers blood lipid level. Its ber content also lowers blood cholesterol level (37, 38). Our result observed a high level of alkaline phosphatase (ALP) enzyme in subjects who had higher potato consumption than those participants who consumed lesser potato it seems that higher potato consumption can cause to leads higher ALP enzyme level. While lower ALP enzyme level observed among subjects who had higher other starchy vegetable consumption.
We found an inverse association between other starchy vegetable consumption and serum level of SGPT.
Moreover, a case-control study among 229 Japanese adults (men and women) with T2DM, who were not taking anti-diabetic medication showed positive correlation of total carbohydrate intake with HbA1c. However, our study with healthy individuals has demonstrated the positive association between other starchy vegetable consumption and higher serum insulin level (39). This is the rst study which examined the association between other starchy vegetables and potato consumption and CVD risk factors among elderly individuals. Limited research is available on the association between other starchy vegetable and potatoes consumption and cardiovascular risk factors. Moreover, not all published studies have comprehensively taken into account different cardiovascular risk factors. However, in the present study, glycemic parameters, lipid pro le and also in ammatory biomarkers were investigated in order to provide better insight into the association with CVD risk factors. Additionally, elderly individuals are at higher risk of cardiovascular disease and a little information is available about dietary patterns and indices in the elderly, therefore examining the association between other starchy vegetables, carbohydrate and cardiovascular risk factors is important.
The current study has several limitations that should be addressed in the interpretation of the ndings. First, this study was designed as a cross-sectional study which it prevents to say causation of outcome and exposure and it is nuclear that maybe participants consumed potato for reducing CVD outcomes. Therefore, it is necessary to study the probable relationship in future prospective studies. It should be noted that the remaining effects of the unknown confounders should be considered in future studies. Another limitation of the study was that the study was conducted on elderly men, although women and men may have different dietary patterns.

Conclusion
In this cross-sectional study, potato may be related to developing CVD risk factors such as TG. However, more research is needed to illustrate the association between other starchy vegetable consumption and CVD risk factors and to understand potential differences by gender and race. Perspective studies may be needed to con rm our ndings.

Declarations Ethical Approval and Consent to participate
Ethical approval for this protocol was given by the National Institute for Medical Research Development (Grant and Ethics Number: 965430). Moreover, all included participants signed the written consent.

Consent for publication
Not Applicable.
Availability of supporting data Not Applicable.

Competing interests
The authors declare that they have no con ict of interest.  as odds ratio and confidence intervals; **P trends are resulted from binary logistic regression.
ted for sex, age, SES, BMI, and energy intake ted for model 1 + smoking, and total dietary fiber intake; Model 3 is adjusted for model 2 + supplement consumption and medication.