Effect of the Type and Emulsification of Dietary Fat on the Carotenoids Absorption

Effect of the Type and Emulsification of Dietary Fat on the Bioavailability of Fat-soluble Nutrients in Human

This study is designed to assess the effects of 1) the emulsification 2) the type of dietary fat on carotenoid (CAT) absorption employing an in-vitro digestion system (Proof of Concept) and well-designed randomized controlled trial.

In all, twenty-five healthy men and women (aged =19 and =45 y, approximately half men and half women, with the expectation that = 20 subjects will complete the study (= 20 % dropout rate)) will be recruited and each subject will participate in 4 trials (randomized and crossover). Anthropometric measurements, including height, weight, waist circumference, blood pressure as well as skin scan carotenoids status will be measured on the screening day as subject baseline information. Prior to each trial, subjects are required a compliance test (CT) visit. On that day, fasting blood will be drawn to analysis the CAT concentration and compare the analyzed CAT concentration to those of testing day baseline to assess the compliance of the washout diet period. Skin CAT scan status will also be conducted. After the CT day, subjects will undergo a 7-day washout period and follow low-CAT diet to reduce circulating, endogenous levels of CAT and minimize the contribution of CAT in the plasma. During the first 5 days, subjects will consume a low-CAT diet (CAT<750µg), and during the 6-7days, subjects will consume an even low-CAT diet (CAT<500µg). The low-CAT diet menu sheet will be provided and dietary instruction to achieve the low CAT diet will be given. Compliance with the low CAT diet will be promoted by daily menu check-off lists and in-person contact on visit day.Subject will be randomly assigned to consume a carefully portioned mix-vegetable salad (including tomatoes, shredded carrots, spinach, lettuce, and Chinese wolfberry) with 4 different oil-water combinations on the 4 meal testing (MT) day. The 4 different oil-water combinations are as follows:1) Olive oil-water mixture (non-emulsified, rich in unsaturated fat);2) Olive oil-water emulsification (rich in unsaturated fat);3) Coconut oil-water mixture (non-emulsified, rich in saturated fat);4) Coconut oil-water emulsification (emulsified, rich in unsaturated fat).On every MT day, fasting blood will be collected for analyzing the CAT levels every 60 minutes for 10 hours and CAT concentration, triglycerides will be analyzed from the collected blood samples. Appetite VAS questionnaire will be conducted every half hour in the first two hours after consuming test meal and hourly conducted till the 5th hour when lunch ( low-CAT (< 2000 µg), low-fat (<2 g)) provided. After consuming the lunch, Appetite VAS questionnaire will be conducted every half hour in the first two hours and hourly till the 10th hour. Thus, the timepoint for appetite VAS measurement will be at 0, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 5.5, 6, 6.5, 7, 8, 9, 10 hour.There are no incidental findings in the current research as we will only collect subject's biological sample (blood) for testing the carotenoids level and blood triglycerides level which are the aim of this study. The rest measurements, including blood pressure, weight, height and waist circumference, they are the baseline information we collect for this study.

Inclusion Criteria:

1. Ability to give an informed consent
2. Age 19 to 45 years
3. Willing to follow the study procedures

Exclusion Criteria:

1. Significant weight change > 3 kg in the past 3 months;
2. Exercising vigorously over the past 3 months (*Defined as having > 6 metabolic equivalents of exercise daily; approximately 20 mins of moderate intensity exercise (e.g. slow jogging);
3. Intestinal disorders including lipid malabsorption;
4. Diabetes or prediabetes (fasting blood glucose > 100 mg/dL);
5. Smoking;
6. Drinking more than 2 alcoholic drinks per day;
7. Taking lipid-lowering medications or dietary supplements affecting plasma lipid-lipoprotein concentration.
8. Menopausal women, those using hormone based contraceptives, those having abnormal menstrual cycles, and those who are pregnant, lactating or planning to become pregnant.
9. Following any restricted diet (e.g. vegetarian)
10. Taking dietary supplements which may impact the outcome of interests (e.g. carotenoids supp.)
11. Insufficient venous access to allow the blood collection