Effect of Different Oil in High Protein Salad Cream
CHAPTER ONE
Objectives Of Study
The overall objective of this study was to identify effect of Different oil in high protein salad cream. The specific goals of this study were therefore to:
1) obtain the dose-response relation in terms of the influence of the amount of added fat (oil) on the intestinal absorption of carotenoids, phylloquinone and tocopherols in salad cream;
2) investigate whether low levels of oils, i.e. 2 g and 4 g, can result in a statistically significant increase in the absorption of the salad bioactives compared with 0 g of oil.
CHAPTER TWO
LITERATURE REVIEW
Association between vegetable intake and micronutrient status
The 2005 Dietary Guidelines for Americans (USDA, 2005) recommend 3 or more servings of vegetables per day. That dietary guideline has not been met by the majority of the population. Kimmons et al. reported less than 1 in 10 Americans consume the recommended servings of fruits or vegetables (Kimmons et al., 2009). Concurrently, inadequate intakes of various micronutrients have been reported in the U.S. population. Data from the 1994 to 1996 Continuing Survey of Food Intakes by Individuals (CSFII) with added values for α-tocopherol (vitamin E) from the US Department of Agriculture National Nutrient Database for Standard Reference Release 15 showed that only a small percentage of the U.S. population (8.0 % of men and 2.4 % of women) met the estimated average requirements (EARs) for vitamin E intake from foods alone (Maras et al., 2004). Daily vitamin A and vitamin K intakes were lower than the recommended amounts as reported in the National Health and Nutrition Examination Survey (NHANES) IV (Center for Disease Control, 2004). These findings support the recommendation to increase vegetable consumption in order to provide adequate intakes of these nutrients. Vegetables are among the primary contributors of fat-soluble nutrients, such as carotenoids, tocopherols (vitamin E) and phylloquinone (vitamin K1). Some vegetable groups serve as the major source of micronutrients due to their micronutrient contents and the frequency of consumption in many populations (Maras et al., 2004). According to 1990 Food and Drug Administration (FDA) Total Diet Study, the top five sources of phylloquinone in American diets are salad cream, such as spinach, collards, broccoli, iceberg lettuce, and coleslaw with dressing (Booth et al., 1996). Green leafy vegetables consumption significantly contributes to carotenoid (Takyi, 1999), tocopherol (Murphy et al., 1990) and phylloquinone (Booth et al., 1996) intakes. Salad cream are among the major sources of vitamin E in the U.S. diet (Maras et al., 2004, Murphy et al., 1990).
The association between vegetable consumption and fat-soluble nutrient intakes prompts the question as to whether vegetable intake affects plasma levels of these nutrients. Total plasma carotenoid concentrations were shown to be proportional to total intakes of fruits and vegetables (Campbell et al., 1994). Salad consumption was associated with higher serum concentrations of micronutrients, including vitamins A and E, as well as provitamin A carotenoids (α and β carotene) (Su & Arab, 2006). Plasma α-carotene, β-cryptoxanthin and lutein concentrations, were found to be indicative of fruit and vegetable intakes (Campbell et al., 1994). Serum β-carotene concentration was reported to be a useful biomarker for fruit and vegetable consumption in French adults (Drenowski & Popkin, 1997). Increased plasma lycopene was observed after supplementation with tomato-based products in both smokers and non-smokers (Chopra et al., 2000). In breastfeeding Indonesian women, significant improvements in vitamin A status were observed after supplementation with pure β-carotene in a simpler matrix, but not after consumption of an additional daily serving of dark green leafy vegetables (de Pee et al., 1995).
Benefits of vegetable intake related to micronutrient status
Dietary patterns characterized by a variety of plant foods, including vegetables, have been linked to a wide range of health benefits. These health benefits include protection against various chronic diseases and increased longevity. Reduction in the risk of chronic diseases has been found in populations with high vegetable intakes. For example, a prospective study in Chinese women (Villegas et al., 2007) showed inverse correlations between the amount of vegetable consumption and the risk of type 2 diabetes. A review of 22 case-control studies and four prospective cohort studies in the 1999 World Cancer Research Fund report showed that vegetable but not fruit consumption, was associated with reduced risk of colorectal cancer (Park et al., 2007). Moreover, vegetable intake was also reported to have implications on bone health due primarily to the nutrient content in vegetables. New et al. (New et al., 2000) found that high intakes of nutrients in plant foods such as zinc, magnesium, potassium, fiber and vitamin C were associated with higher bone mass in premenopausal women. Further study by the same group reported dietary effects on bone mass and bone metabolism that may link plant foods, including vegetable consumption, to higher bone mass and decreased bone resorption (New et al., 2000). Moreover, a diet consisting of olive oil and raw vegetables was shown to improve longevity in Italian elders (Masala et al., 2007).
CHAPTER THREE
RESEARCH METHODOLOGY
Subjects and Methods
Subject recruitment
The screening of subjects consisted of two steps including an interview and a blood screening. The initial screening procedures consisted of a standardized interview addressing health and lifestyle factors and a written SCOFF questionnaire (Morgan et al., 1999). The interview was followed by measurements of height and weight. Subjects that passed the initial screening were invited to complete blood screening consisting of a cell blood count, blood biochemistry profile, and plasma lipid panel. The exclusion criteria were designed to eliminate factors known to interfere with lipid metabolism, as well as the absorption and metabolism of target analytes. The inclusion criteria included females 18-39 years of age and excellent health as indicated by health history, complete blood count, and blood biochemistry profile, and normolipidemia as indicated by the plasma lipid panel. The exclusion criteria included cigarette smoking (previous 12 months), frequent alcoholic beverages consumption (> 1 drink/day), current or recent (previous 1 mo) use of dietary supplements, plant sterols and/or medications known to affect lipid metabolism, use of hormonal contraceptive (previous 6 months), pregnant or planning a pregnancy, history of eating disorder, BMI ≥ 30, food allergies and modified diet (e.g., vegetarian). Also excluded were those with a history of restrictive eating – which was assessed by the SCOFF questionnaire (Morgan et al., 1999). Subjects with 2 or more “yes” responses were excluded. All documents and procedures involving human subjects were approved by the Iowa State University Institutional Review Board.
Experimental diets
Subjects were given a list of foods and beverages that are high in carotenoids, vitamins A, E, and K (Appendix A) and were asked to avoid the listed foods and beverages for days 1-3 of each of the five study periods. On day 4, subjects consumed a weighed, standardized diet low in carotenoids, and vitamins A, E, and K (Appendix B). The nutrient contents of the diet were analyzed by Nutritionist Pro™ nutrient analysis software, version 4.4 (Axxya Systems, Stafford, TX). The daily diet provided an estimated 9.49 MJ, 73.9 g protein (12.8% of energy), 52.5 g fat (20.4% of energy), and 386.4 g carbohydrate (66.8% of energy). The calculated carotenoid, tocopherol, vitamin A, and vitamin K1 contents of the experimental diet were 0.0 µg α-carotene, 10.8 µg β-carotene, 4.3 µg β-cryptoxanthin, 97.6 µg lutein (plus zeaxanthin), 0.0 µg lycopene, 0.7 mg α-tocopherol, 54.7 µg RAE vitamin A, and 20.0 µg vitamin K1. On day 5, subjects consumed a reduced fat (2 g fat) snack and a low fat (3 g fat) lunch following the consumption of the test salad. These foods contained low amounts of carotenoids, tocopherols, vitamin A and vitamin K. All foods were consumed under supervision at the Iowa State University Nutrition and Wellness and Research Center (NWRC) except for the lunch and afternoon snack, which were carried out.
CHAPTER FOUR
RESULTS
Subject characteristics
The average age of the twelve female subjects was 24.0 ± 5.9 y; the mean (± SD) body mass index (BMI) was 23.60 ± 3.43 kg/m2. Non-compliances with the study protocolwere reported by two subjects; the use of a single-dose of 3 mg drospirenone/ethinyl estradiol during the third intervention period and the daily use of Orthocyclin for two weeks preceding the test salad consumption during the fifth intervention period. Both hormone treatments may have influenced plasma chylomicron clearance (Berr et al., 1986). Results were excluded for the PP statistical analyses and included in the ITT analyses.
Carotenoid, phylloquinone and tocopherol composition of the test salad
The total amounts of carotenoids, phylloquinone and tocopherols in the test salad were 29.44 mg, 0.23 mg, and 4.138 mg respectively (Table 7 & 8). The carotenoid, phylloquinone and tocopherol contents in the individual salad cream were comparable to the amounts reported in the USDA National Nutrient Database for Standard Reference (USDA, 2009). The variation in nutrient contents of the test salads across study periods was minimized by obtaining prepackaged vegetables from the same brands. In addition, spinach and romaine lettuce were sorted according to leaf coloration to maintain uniformity in carotenoid content. As reported in our previous salad study (Brown et al., 2004), zeaxanthin had the most variable content among the measured carotenoids. α– and γ– Tocopherol varied the most among all analyzed nutrients in the test salad, which may be due to the duration of the study that included weeks from June to September. The tocopherol content in vegetables is substantially affected by the growing conditions (weather, growing season, intensity of sunlight, and soil state) (Bauernfeind, 1980). Analysis of the stripped soybean oil used in the firt, third and fifth study periods showed consistent concentrations of α-tocopherol and γ– tocopherol.
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