A postprandial intervention study is conducted on healthy male subjects to evaluate whether the addition of proteins (why protein isolate, soy protein) can help to increase the bioavailability of carotenoids from a tomato/carrot beverage.
Participants who agree to sign the Informed Consent Form and are considered eligible for participation will be scheduled for a first and brief screening visit enrolment visit) to collect a spot urine and blood sample (20 ml) that are meant to check the subjects anemic status and analyze the sugar levels as well as plasma lipids such as triglycerides, in order to screen for any abnormal health condition (e.g. onset of diabetes) that they might not be aware of at the date of the information session and that might not make them eligible for this study. If at this stage they are still considered eligible for the study, participants will commence the 4 week trial phase which includes 3 washout periods, 1 short screening visit and 3 full day (i.e. 10.5 hours) clinical visits. The screening visit, called preliminary visit, will take place at the beginning of the trial phase. A blood sample will be collected to determine the baseline levels of triglycerides and plasma carotenoids at the beginning of the trial, prior to the first washout phase. The first washout week starts on day 1 after the preliminary visit and will have a duration of 14 days during which the participants will be asked to stay on a low carotenoid diet (i.e. to avoid the intake of colored fruits and vegetables), to reduce the basal levels of blood circulating carotenoids. During the 1-day appointments at the Clinical and Epidemiological Investigation Centre (CIEC), one of the three test meals will be given to the participants in 6 different orders, making 6 treatment patterns. Assuming that all 24 participants are successfully recruited, we will have 4 randomly allocated participants per pattern. On clinical visit days, participants will be asked to report at the CIEC's facilities, starting from 7:30 am, and a baseline blood sample (20 ml) will be drawn at 0h time point. A trained nurse will insert a cannula in the forearm of the participant that will be left in place during the whole staying for the commodity of the participant. Immediately after the baseline blood draw, a test meal composed of a mixture of carrot and tomato juice (350 mL in total), to which 5 mL of peanut oil will be added, 40 g of toasted bread (white wheat, with 10 g margarine plus 20 g cream-cheese) and a glass of water (approx. 300 mL) which may or may not contain 30 g of proteins (either a plant based protein or a dairy-based proteins) will be served. The entire test meal must be eaten within 30 min, under supervision. Post-prandial blood samples (20 ml each) will be collected at timed intervals (before, 2h, 3h, 4h, 5h. 6h, 8h and 10h after test meal intake). Participants will receive a standardized lunch 4 hours after test meal intake (c.a. 12:00 pm), consisting of a toasted sandwich (white wheat bread, ca 60 g), with ca. 60 g turkey with some margarine to spread on the bread (ca 10 g), a Greek yogurt (140 g) and a small apple. A courtesy meal 10 hours after test meal intake for dinner and at the end of the visit. No other foods or beverages except water (ad libitum) will be allowed during the day (including during breakfast and lunch if desired). This first clinical appointment will be followed by a 1 week washout period, during which he/she will continue on a low carotenoid diet (3rd week of washout diet). At the end of the 3rd week of washout, the second appointment at the LIH clinical center will take place. The procedure for this day is the same as mentioned above. The second appointment is followed by the 4th and last washout week and at the end the participant will have the 3rd and last appointment at the Luxembourg Institute of Health (LIH) clinical center, which will be identical to the other visits. For all washout periods the participants will be asked to fill a provided food journal, on a daily basis, where they will write down what they have eaten during the day. This will be used to check compliance with the washout period and better interpret personal data. Stool collection: For a limited number of subjects (n=6), the samples will be collected following intake of all 3 test meals. For this purpose, Containers for collection and plastic clip-bags and bags will be handed to participants. Boxes with cooling elements for stool collection will likewise be given. Also, six fecal color markers will be provided to the participants. For each clinical visit, two fecal marker are needed. Collections will start from the excretion of the first fecal color marker (brilliant blue) which will be taken at the beginning of the fasting period, i.e. the day before each clinical day. The collection will continue to the excretion of the second fecal marker which should be taken on the morning of the day following each clinical visit (before breakfast). Samples will be returned after the clinical test day as soon as the last fecal marker has been excreted (normally resulting in 2-3 day complete fecal samples), and could be collected once in between by staff from the LIH if needed.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
24
Test meals will be served to the subjects, containing soy protein isolate: 350 mL carrot/tomato juice (50:50, v/v), with 30 g added soy protein, plus 5 ml peanut oil as morning test meal, served together with 40 g toasted bread and 20 g of cream-cheese plus 10 g margarine.
Test meals will be served to the subjects, containing soy protein isolate: 350 mL carrot/tomato juice (50:50, v/v), with 30 g added whey protein isolate, plus 5 ml peanut oil as morning test meal, served together with 40 g toasted bread and 20 g of cream-cheese plus 10 g margarine.
Luxembourg Institute of Health
Strassen, Luxembourg
Concentration of carotenoids in plasma triacyl-rich-lipoprotein (TRL) fraction
Carotenoid concentration (lycopene, beta-carotene) studied over 10 hours postprandial (area-under curve of concentration vs. time)
Time frame: 10 hours postprandial, measured on 3 test clinical test days after test meal intake, interspersed by 1 week each
Time of maximum concentration of lycopene and beta-carotene and triglycerides in plasma-TRL fraction
Studying the timely appearance of carotenoids in the plasma TRL fraction, i.e. the time when concentration with reach a maximum
Time frame: 10 hours postprandial, measured on 3 clinical test days after test meal intake, interspersed by 1 week
Maximum concentration of lycopene and beta-carotene and triglycerides in plasma-TRL fraction
Studying the maximum concentration of lycopene and beta-carotene in the plasma-TRL fraction, i.e. the maximum concentration reached during the 10 h monitoring
Time frame: 10 hours postprandial, measured on 3 test clinical days after test meal intake, interspersed by 1 week
Fecal degradation products of carotenoids
Studying native carotenoids and degradation products in pooled stool excreted following test meal intake (fecal balance method), i.e. the stool collected following test meal intake
Time frame: Collection covering the test meal intake period, starting from the excretion of a brilliant blue capsule taken the 12 hours before test meal intake, until complete excretion of a second brilliant blue capsule taken 24 hours after test meal intake
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Test meals will be served to the subjects, containing soy protein isolate: 350 mL carrot/tomato juice (50:50, v/v), plus 5 ml peanut oil as morning test meal, served together with 40 g toasted bread and 20 g of cream-cheese plus 10 g margarine.