hep 491 paper v5 jc

AN EVALUATION OF A THREE-DAY DIET AND HYPERTENSION

An evaluation of a three-day diet and hypertensionJoseph A. Cruz1 & Deborah L. Feairheller, PhD1

1The HEART (Hypertension and Endothelial function with Aerobic and Resistance Training) Laboratory, Health & Exercise Physiology Department, Ursinus College, Collegeville, PA.

Funding: No external financial support.

Author Correspondence:Deborah L Feairheller, PhDThe HEART (Hypertension and Endothelial function with Aerobic and Resistance Training) Laboratory, Health & Exercise Physiology Department, Ursinus College,601 E. Main Street, Collegeville, PA 19426Tel#: 610.409.3256Email: [email protected]

Disclosure: We have no conflicts of interest to declare.

IntroductionOverview

There has always been a light of hope in the advancing research of the medical field for new approaches to diagnose, cure and prevent individuals from developing cardiovascular disease (CVD). CVD is referred to as an umbrella that covers a variety of diseases that involve the cardiovascular system and overall the entire homeostatic environment of the human body. Hypertension, or high blood pressure, is classified as one of the many manifestations within this CVD umbrella and is usually defined as abnormal elevated pressure exerted on the walls of the blood vessels. Inadequate control of blood pressure can progress to more serious cardiovascular (CV) diseases such as atherosclerosis, myocardial infarction, stroke and death.

There have been several variations to dietary guidelines suggested that may prevent CVD and promote improved health in individuals. Each of these has been researched prospectively and proven effective (Lane, 2008). Within these guidelines, vitamin D has been researched extensively and has been reported to lower blood pressure in hypertensive adults, but there has yet to be a large randomized control trials to prove the accuracy of these findings. Along with the lack of evidence of the antihypertensive effects of vitamin D, there is also little research on three-day diet and the information that can be retrieved from an analysis. There is limited research of the effects that vitamin A may have on cardiovascular risk markers. Further, dietary fiber has been researched and continues to be researched. There are proposed effects that adequate dietary fiber can lower blood pressure as well as decreasing other cardiovascular and inflammatory risk levels. Iron is also associated with the cardiovascular system and the pulmonary system in terms of its function. Inadequate levels of iron are seen in all populations and is the reason for being the most common dietary deficiency. The risk of deficiency in this daily nutrient may cause an increase risk in cardiovascular disease. The purpose of this study is to conduct a cross-sectional study and to observe self-reported three-day diets and any

Cruz, HEART Laboratory, Ursinus College1


correlations seen within the individual’s diet and the necessary macro- and micronutrients, specifically vitamin D, vitamin A, dietary fiber, and iron.

Guidelines

Dietary guidelines have been generated to give the population recommendations of healthy habits on daily nutritional consumption. Most dietary guidelines are similar in their key recommendations internationally (Hansen, 2014). The guidelines call for a diet that accounts for all macro- and micronutrients that are within appropriate calorie limits, reducing sodium, added sugar, saturated fatty acids and trans fatty acids, while increasing potassium and fiber intakes (Reidlinger, 2015). Healthy eating patterns suggested by the present 2015-2020 Dietary Guidelines include increasing whole grains, whole fruit and vegetable consumption. Low-fat, or fat free dairy products are preferred. Protein food should include high amount of seafood, lean meat, legumes, nuts, and seeds. Also the guidelines state to avoid foods that contain high amounts of trans fat, saturated fats, added sugars, and sodium by reducing intake to 10 percent of calorie limit each. If alcohol is consumed, recommendations state that it should be consumed in a timely manner as well as limiting consumption to 1 or 2 drinks for women and men, respectively (US Dept. of Heath and Human Services and US Dept. of Agriculture, 2015).

Vitamin A

Not much research has been conducted on vitamin A and it’s affects on cardiovascular risk markers. Vitamin A is a nutrient that can be either consumed through animal or plant sources or be converted from other carotenoids; such as beta-carotene and beta-cryptoxanthin. Carotenoids, such as beta-carotene and beta-cryptoxanthin, are consumed through plants and can be converted to vitamin A (Bates, 1995). Dark green, yellow, and orange fruits and vegetables are rich sources of these provitamin A carotenoids. Bates also states that there may be immunity improving effects, prevention of degenerative diseases, and decrease in overall mortality.

Vitamin D

Vitamin D is a necessary dietary component in the body’s homeostatic environment. This nutrient has had several claims and suggestions that it plays a vital role in the prevention of many chronic diseases including cardiovascular disease, one of the top leading causes of death in the United States. Vitamin D exists in two forms; vitamin D2 is derived from plant sources where vitamin D3, or the “sunshine vitamin”, is synthesized from the ultraviolet irradiation, or from oily fish or supplements (Mozos, 2014). Recently in the United States, there has been an increase in the number of outpatients who can be classified as vitamin D deficient from 2007 to 2010 (Huang, 2015). To define vitamin D deficiency, Mozos (2015) stated that most experts define vitamin D deficiency and insufficiency as a concentration level of calcidiol, which is generated from the substrate 25-hydroxyvitamin, of <20 ng/mL and 21 – 29 ng/mL. If vitamin D is >30 ng/mL it is classified as sufficient and if concentrations are >150 ng/mL, then the patient can be classified to have vitamin D intoxication. Vitamin D can be consumed through protein sources, specifically fish, fortified cereals, and dairy products.

Dietary Fiber

Dietary fiber has been seen to have protective and preventive properties from the risk of developing hypertension. It has been reported to have an inverse relationship with Peripheral Artery Disease (PAD), a major cause of mortality which results from atherosclerosis, coronary artery disease, hypertension, and cigarette smoking (Merchant, 2003). The intake of adequate



levels of dietary fiber have proposed roles of decreasing blood pressure, cholesterol levels, and inflammation biomarker levels (Grooms, 2013). Fiber can be consumed from whole grains, especially fortified cereals, fruits, vegetables and supplementation.

Iron

Iron is a vital element within the cardiovascular and pulmonary systems of the body. It aids in the important transport of oxygen within the blood to the other organs and tissues within the body as well as cell growth and proliferation. Iron deficiency, assumed to be the most common dietary deficiency, is a prime cause of worldwide anemia (Ponikowska, 2013). Food fortification, dietary diversification and iron supplementation are strategies that aim to control adequate iron levels, however it has been seen that higher food intakes can lead to increased risk of CVD (Geissler, 2011). Rich sources of iron exist in protein sources including red meat, pork, poultry and seafood, dark leafy vegetables and iron-fortified cereals.

Diet Interventions

Most diet interventions performed in prospective studies applied either one or a combination of multiple interventions including the Dietary Approaches to Stop Hypertension (DASH) diet, Mediterranean diets, low-sodium diets, low-calorie diets, and low-fat diets (Gay, 2016). Most of these diets mimic dietary guidelines and aim to reduce the amount of proposed nutritional components that may increase risk for CVD or other chronic diseases. The DASH diet is aimed to increase fruit, vegetables, low-fat dairy, whole grains, lean meat and fish, along with nuts and oils; while avoiding red meat, added sugars, and increased sodium (Wengreen, 2013). The Mediterranean diet is more focused on increased vegetables, fruits, nuts, legumes, cereals, high intake of oils (especially olive oil), low-moderate intake of dairy and alcohol, and a preference of fish over meat and poultry (Leblanc, 2015). Low-sodium diets aim to reduce amount of sodium consumed. Similarly, low-calorie diets aim to reduce calories and low-fat diets aim to reduce mostly saturated or all fat intake. In respect, there have been reports of combinations of more than one of the diets listed.

Methods

Participants

Young participants were recruited from the Ursinus College area. Specific criteria for inclusion for all participants were: non-diabetic, non-smoking, no medications that affect cardiovascular hemodynamics, no more than one anti-hypertensive medication, and no evidence or history of CVD, hypercholesterolemia, or renal disease. Each participant gave written informed consent and completed a health and exercise history questionnaire. The protocol was approved by the Ursinus College Institutional Review Board, and all procedures were in accordance with the ethical standards of the Helsinki Declaration.

Blood Pressure Measurements

Clinic BP measurements were obtained in accordance with JNC-7 guidelines on three separate visits in a quiet (5min rest), temperature controlled room, using an aneroid sphygmomanometer (Medline Industries, Mundelein, IL) (Chobanian, Mozaffarian, Roger, et al., 2003). BP measurements were performed in triplicate with the average of the three values used as the representative BP



Body Composition Measurements

Body composition was measured by whole-body bioelectrical impedance (BIA) using the single frequency impedance instrument (ImpediMed DF50, San Diego, CA) following an overnight fast in a quiet, temperature controlled room. Participants were asked to refrain from salty foods, exercise, medication, alcohol, and caffeine for at least 10 hours prior to the test. Height and weight were measured using a calibrated electronic scale without shoes. BIA was measured in accordance with the manufacturer’s instructions at 50 kHz on the right side of the body. Two electrodes were placed on the dorsal right hand and foot while the athletes were lying in a supine position. Three measurements were taken, and the mean values of impedance, phase, resistance, and reactance were used for calculations of total fat and fat free mass.

Diet Analysis

Self-report three-day diet logs were collected. We requested that they include two weekdays (and one weekend day. Diet logs were assessed by the Diet Analysis Pus software (Cengage Learning, Stamford, Connecticut) for calculation of daily kilocalorie, nutrient, and mineral content. An average was then calculated for the three-day period.

Statistics Analysis

Data are expressed as mean ± the standard deviation (SD). Distribution of all variables was examined using the Shapiro-Wilk test of normality. Pearson correlation was used to determine if there were relationships between the variables and was further examined by linear regression analysis. Statistical significance was set at P < 0.05. All statistical analyses were performed using SPSS version 19.0 (SPSS Inc., Chicago, IL, USA).

Results

Participant Characteristics

There was a total of 92 relatively young participants that had three-day diet included into the statistical analysis. The mean age of all participants was 23.61 9.3 years old, and were predominated by males (65.2%, n = 60) and of the Caucasian ethnicity (87%, n = 80). The participants seemed to be healthy since mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) were recorded as 120.91 9 mmHg and 73 6.8 mmHg, respectively. Mean body fat% was 27.10 8.68 and the mean Body Mass Index (BMI) was 26.36 3.58. The participant characteristics can be seen in Table 1.

Diet Characteristics

In Table 2, mean diet characteristics of the self-reported three-diet of all the participants is presented. Mean average of all patient’s kilocalorie (kCal) was 2470.13 758.66. Out of the averaged patient consumption, intake carbohydrates consisted of 47.32%, protein was 18.86% and fat 33.79% of averaged kCal. Average Cholesterol (mg) intake was observed at 520.07 527.26; average dietary fiber (g) was 23.40 8.62; and average sodium intake (mg) was measured at 4298.88 2064.96. Sugar (g) consumption was measured at 104.41 41.44



Relationship with Cardiovascular Markers

There were only three significant relationships seen through all correlations. There was a direct relationship with sodium intake and BMI (p = 0.218), presented in Figure 1. In contrast, there were two inverse relationships with fiber (p = -.247) and iron (p = -.227) correlating with SBP. Graphs presenting both the fiber and iron relationships with SBP can be seen in Figure 2 and Figure 3, respectively.

Discussion

The present study was performed to observe any correlations or significant relationships between diet characteristic components and health among young participants. There were more specific target nutrients that we hoped to see correlations including vitamin D and A; however we only found three significant findings which were associated with sodium, dietary fiber, and iron intakes.

The mean values of the diet characteristics show that the participants within the study consumed well over in kilocalories (kCal), protein, carbohydrates, fat, saturated fat, cholesterol, and sodium; whereas the rest of the variables seem to be under or near the recommendations. Most of the participants within the study are college aged (18-22) with few outside those years. These years can be considered a transitioning year where adolescents turn to adults and are required to make challenging lifestyle choices that may affect their health habits. Schweitzer et al. (2016) explains the “freshman 15” phrase which describes weight gain associated with the initial years of college. This weight gain can be associated with poor dietary choices and in the end result in skipping meals, increased frequency of snacks and alcohol, and overall, increased fat, added sugars, and increased sodium intake. As well as unhealthy eating habits, environmental factors such as stress can be an indication for the reason for some of the choices taken by young adults in college years (Nastaskin, 2015). This seems to be typical of most young adults and we see similar outcomes within our study as well.

The study presented that there was a positive correlation with dietary sodium intake and BMI. This seems to be a plausible indication due to increased sodium content in foods is linked to unhealthier foods which overall leads to increased body composition and BMI. However, there has not been may studies that looked at the effects of sodium on body composition. Sodium intake has been considered one of the major causes for hypertension among adults, but Shim et al. (2013) found that, within his study on the association of dietary sodium intake with meal and snack frequency, dietary sodium was positively correlated with systolic blood pressure for both males and females and an additional correlation with BMI seen for only males. The participants were young adults between the ages of 20-26 years old and both males and females had daily sodium intake percentages well over recommended values, 310% and 245%, respectively. In contrast, Vaidya and associates (2011), studied associations between adiponectin and 25-hydroxyvitamin D (25[OH]D) after controlling the influence of the renin-angiotensin-aldosterone system (RAAS) with dietary sodium equilibration. After all subject performed one week of a high sodium diet to suppress RAAS and one week of a low sodium diet to stimulate RAAS, they saw that the sodium intake equilibrium was not associated with BMI.

It was seen in the present study that there was an inverse relationship with dietary fiber intake and systolic blood pressure. This negative correlation has been reported before in existing



research. In a meta-analysis conducted by Whelton et al. (2005), the authors included 25 randomized controlled trials and assessed the effects of dietary fiber on blood pressure and found that overall, there was no significant reduction in SBP of -1.15 mmHg, but a significant reduction in DBP of -1.65 mmHg. Furthermore, Whelton recorded that both SBP and DBP (SBP -5.95 mmHg; DBP -4.20 mmHg) were significantly reduced in hypertensive patients. It has also been seen that cereal fiber intake reduced the risk of peripheral artery disease (PAD) in men (Merchant, 2003). However, there has been research that has recorded no significant effect on blood pressure with dietary fiber. In a study conducted by He et al. (2004), with 110 patients, found that there were no significant reductions in both SBP and DPB after after a six-week fiber intervention. The effects of dietary fiber still seem to be questionable since there have been recordings of both significant and non-significant effects towards blood pressure. It has been seen to reduce blood pressure within hypertensive adults but not for young healthy individuals.

A negative correlation was seen with iron intake and SBP. There is a lack of research performed on the potential effects that dietary iron has on protecting and controlling blood pressure levels. It has been recorded by Tzoulaki (2008), within a large sample size of 4,680 adults, that both dietary total iron and non-haem, iron found only in plant sources, were inversely related with blood pressure.

Limitations

Some limitations that could be considered is the lack of variety in population sample. Most of the participants included in this study were athletes within their in-season period of sport. This could be a reason why some data seemed to be skewed and showed undesirable data. Along with sports dominating the sample, a self-reported three-day diet analysis can only show limited accurate values in an individual’s diet.

Conclusion

In conclusion, examining more population based diets especially younger adults can provide substantial information in the dietary habits and trends that may lead to causes increased risk of specific cardiovascular markers. Unfortunately, no significant findings were recorded for vitamin D and A; however, there was significant correlations that were recorded with a direct relationship with sodium and body composition along with an inverse relationship of dietary fiber and iron with SBP. This calls for further research in diet analysis and/or prospective randomized controlled trials of larger sample size. With this need for further investigation, it can provide evidence to the proposed allocations.



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Table 1. Study Participant Characteristics

Data are represented as mean of ± SD. *SBP, systolic

blood pressure; DBP, diastolic blood pressure;

BMI, body mass index.



Table 2. Participant Diet Characteristics

Data are represented as mean of ± SD. *kCal,



kilocalories; Sat.Fat, saturated fats; Mono.Fat,

monounsaturated fat; Poly.Fat, polyunsaturated fat;

Trans.Fat, trans fatty acids.

Figure 1.

Correlation of sodium intake and Body Mass Index (BMI)

Figure 2.

Correlation of dietary fiber and systolic blood pressure.



Figure 3.

Correlation of iron and systolic blood pressure.


hep 491 paper v5 jc

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