The main objective of this human trial is the demonstration that β-carotene in fortified maize has good bioavailability as a plant source of vitamin A and that when humans ingest the biofortified product retinol levels are higher than when they ingest non biofortified white maize.

Human feeding trial with fortified maize is part of the BIOFORCE project which aims to create transgenic cereal plants that will provide a near complete micronutrient complement for malnourished people. β-Carotene intake helps to balance inadequate retinol supply in significant parts of the world. In order for plants with enhanced levels of micronutrients to be useful, the micronutrients must be present in a bioavailable form that can be absorbed by the human body. To test the main hypothesis of the trial an open-label, randomized, three-way crossover trial consisting of three 7-day feeding periods has been designed. The study will compare three different feeding conditions: β-carotene fortified maize containing diet, white maize containing diet supplemented with a reference β-carotene dose and white maize diet. The study will test the hypothesis that a meal including fortified maize yields superior all-trans retinol area under the plasma concentration versus time curve (AUC) values than an isocaloric and isoprotein meal with normal maize.

After a first screen that will address physical conditions and lifestyle 18 volunteers (9 men and 9 women) who meet the eligibility criteria will be included in the study once they have read and sign the informed consent. The postprandial plasma all-trans retinol response to each test meal will be used to establish the bioavailability of provitamin A from fortified maize. The test meals will be consumed in random order separated by 1 week. Blood samples will be collected over 8 h. All-trans retinol will be analyzed in plasma by high pressure liquid chromatography (HPLC) with coulometric array electrochemical detection.

Mean AUC for all-trans retinol in plasma after ingestion of the β-carotene-fortified maize porridge, the white maize porridge with the β-carotene reference dose, and the white maize porridge will be compared.

Inclusion Criteria:

• Healthy persons
• Persons who had not taken vitamin A or β-carotene supplements within the past month

Exclusion Criteria:

• Current or recent (previous 12 mo) cigarette smoking
• Frequent consumption of alcoholic beverages (1 drink/d)
• Current or recent (previous 1 mo) use of dietary supplements
• Current or recent (previous 6 mo) use of hormonal contraceptives
• Current or recent (previous 1 mo) use of medications known to affect lipid metabolism.
• History of restrictive eating
• BMI under 20 or over 30
• Lactose intolerance
• Vegetarians.
• Severe or symptomatic cardiac disease or hypertension
• History of bleeding disorders
• Chronic history of gastric, intestinal, liver, pancreatic, or renal disease
• Any portion of the stomach or the intestine removed (other than an appendectomy)
• History of intestinal obstruction, malabsorption, or use of antacid drugs; cancer (active or use of medications for a history of cancer treatment within the past 5 y)
• History of chronic alcoholism
• History of convulsive disorder
• Evidence of active drug abuse