Title The use of a commercial vegetable juice as a practical means to increase vegetable intake : a randomized controlled trial Permalink

Background: Recommendations for daily dietary vegetable intake were increased in the 2005 USDA Dietary Guidelines as consumption of a diet rich in vegetables has been associated with lower risk of certain chronic health disorders including cardiovascular disease. However, vegetable consumption in the United States has declined over the past decade; consequently, the gap between dietary recommendations and vegetable intake is widening. The primary aim of this study is to determine if drinking vegetable juice is a practical way to help meet daily dietary recommendations for vegetable intake consistent with the 2005 Dietary Guidelines and the Dietary Approaches to Stop Hypertension (DASH) diet. The secondary aim is to assess the effect of a vegetable juice on measures of cardiovascular health. Methods: We conducted a 12-week, randomized, controlled, parallel-arm study consisting of 3 groups of freeliving, healthy volunteers who participated in study visits at the Ragle Human Nutrition Research Center at the University of California, Davis. All subjects received education on the DASH diet and 0, 8 or 16 fluid ounces of vegetable juice daily. Assessments were completed of daily vegetable servings before and after incorporation of vegetable juice and cardiovascular health parameters including blood pressure. Results: Without the juice, vegetable intake in all groups was lower than the 2005 Dietary Guidelines and DASH diet recommendations. The consumption of the vegetable juice helped participants reach recommended intake. In general, parameters associated with cardiovascular health did not change over time. However, in the vegetable juice intervention groups, subjects who were pre-hypertensive at the start of the study showed a significant decrease in blood pressure during the 12-week intervention period. Conclusion: Including 1-2 cups of vegetable juice daily was an effective and acceptable way for healthy adults to close the dietary vegetable gap. Increase in daily vegetable intake was associated with a reduction in blood pressure in subjects who were pre-hypertensive at the start of the trial. Trial Registration: Clinicaltrials.gov NCT01161706 Background For almost two decades, the United States Department of Agriculture (USDA) has recommended that Americans consume a minimum of 5 servings of vegetables and fruits a day [1]. These recommendations are based on numerous studies showing that meeting the recommended daily intake of fruit and vegetables is associated with a reduced risk for a number of chronic diseases, with the evidence for cardiovascular disease and stroke being particularly strong [2-5]. In 2005 the Department of Health and Human Services updated the Dietary Guidelines which recommended an increase in fruit and vegetable intake and changed the recommendations from servings to cups [6]. The new goal was 26.5 cups (equivalent to 4 13 servings) according to an individual’s sex, physical activity and age [6]. For this * Correspondence: clkeen@ucdavis.edu Department of Nutrition, University of California Davis, One Shields Ave, Davis, California 95616, USA Full list of author information is available at the end of the article Shenoy et al. Nutrition Journal 2010, 9:38 http://www.nutritionj. com/content/9/1/38 © 2010 Shenoy et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. study, which focuses on vegetable consumption, the Dietary Guidelines suggest that 21⁄2 cups of vegetables per day are recommended for a reference 2,000-calorie intake [6]. Despite numerous intensive public educational campaigns, surveys examining trends in vegetable consumption from 1988 to 2002 show that 7 out of 10 Americans consume less than the USDA recommended servings of vegetables each day and suggests that 25 percent of respondents had no daily vegetable intake at all [7]. There are multiple reasons for low vegetable intake in the United States, including perceived high costs [8], lack of awareness of the benefits of vegetable consumption [9-11], low availability of fresh products in certain areas [12], taste concerns [13], and limited food preparation time and skills [14]. A consequence of low vegetable consumption can be a low intake of essential nutrients that are key factors for vascular health such as potassium and vitamin C, as well as decreased sources of phytochemicals, such as flavonoids and carotenoids, which have a number of putative positive vascular health benefits [15,16]. Given these factors, there is a need to develop new strategies that can close the gap between what is recommended for vegetable intake, versus what is actually occurring in the general population. Logically the solutions that are advanced for closing the gap between intake and recommendations should be convenient, calorie appropriate, cost effective, and supported by sound science [17]. The Dietary Approach to Stop Hypertension (DASH) diet was originally designed for those with cardiovascular risk factors, such as hypertension [18,19], but it was subsequently recommended as one of two healthy eating patterns for the general U.S. population in the 2005 Dietary Guidelines [6]. Adherence to the DASH diet has been shown to be associated with improved vascular health in a number of trials [9,20,21]. The primary objective of the current study was to determine if the incorporation of a vegetable juice is a practical way for individuals to help meet dietary recommendations for daily vegetable intake as described by the 2005 Dietary Guidelines and the DASH diet. Other goals were to obtain preliminary evidence about the impact of vegetable juice consumption on cardiovascular health by measuring blood pressure, lipid profiles and other related parameters.