Healthy
Conditions
Keywords
vitamin A, beta Carotene, diet, nutrition, nutritional requirements
Brief summary
A controlled dietary intervention study will be carried out based on the stable isotope method the investigators have developed to quantify both the absorption of beta-carotene and its bioconversion to retinol in oil and in a mixed diet. For 6 weeks the participants will consume 2 capsules/day, 7 days/week with each capsule containing 50-mg \[13C10\] beta-carotene and 50-mg \[13C10\] retinyl palmitate. For three weeks they will consume a diet with high levels of beta-carotene in vegetables and fruits and for the other 3 weeks they will consume a diet with low levels of beta-carotene in vegetables and fruits supplemented with an extra amount of beta-carotene in oil. Samples of blood and faeces will be taken. The study hypothesis is that the absorption of beta-carotene in oil in comparison with the absorption of beta-carotene in a mixed diet differs by a factor of 3 to 6. The investigators want to measure the influence of the food matrix of vegetables and fruits on the absorption of beta-carotene in healthy humans on a western diet.
Interventions
Sponsors
Dutch Dairy Organization (NZO)
Radboud University Medical Center
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
PREVENTION
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
* Men and women between 18 and 50 years old * Body mass index (BMI) between 18 and 25 kg/m2 * Willing to consume the controlled diet and not consume other food items * Willing to consume the cooked meal at the research facility and the bread meals and snacks at home (distributed to the participants) * Willing to consume the capsules every day
Exclusion criteria
* Hematological diseases and chronic diseases including cancer, renal insufficiency, liver disease, diagnosed gastrointestinal disorders, or surgery of the gastrointestinal tract * Use of (oral) drugs suspected of interfering with fat-soluble-vitamin absorption * Smoking * Excessive alcohol consumption (\>30 g/d) * Consumption of vitamin or carotenoid supplements 6 weeks before and during the study * Not too low or high levels of serum beta-carotene and retinol * Normal hemoglobin, hemocytometry, creatinine, ALAT, alkaline phosphatase, and cholesterol blood values (compared with laboratory references) * Pregnancy
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| levels of retinol and carotenoids and the degree of isotopic enrichment in serum (fasting blood sample) and in faeces (72 hour collection) at the start and at the end of each of the 3-week periods | — |
Countries
Netherlands
Outcome results
None listed