Bioavailability of Carotenoids Added Into Processed Foods

Carotenoids are a family of pigments found abundantly in fruits and vegetables. They are responsible for the colour of many fruits and vegetables such as tomatoes, melon, peppers and orange coloured fruits and vegetables. Carotenoids such as beta-carotene are important for the human body as precursors of vitamin A. They are also thought to be important as anti-oxidants and may help protect against cancer and heart disease. Although many foods are rich sources of carotenoids poor bioavailability often limits the amounts that are absorbed and available for metabolism in humans.

Devising practical ways and means of increasing carotenoid bioavailability could lead to better health outcomes. Processed foods are now widely eaten by many, both for their taste and convenience. No studies have thus far looked at the bioavailability of carotenoids that have been added into processed foods. Thus the purpose of this study is to investigate the bioavailability of carotenoids that have been incorporated into processed food products (bread and mayonnaise).

Carotenoids are a diverse group of natural-occurring fat-soluble pigments. Whilst over 600 different types have been characterised around 20 have been found in human tissue in the postprandial state, however, over 90% of these absorbed carotenoids are made up of 6 specific types (alpha-Carotene, beta-carotene, Lycopene, Lutein, Zeaxanthin and Cryptoxanthin)

There is good evidence to suggest that carotenoids play a notable role in human health both through their pro-vitamin activity and as biological antioxidants. Carotenoids are believed to be responsible for the beneficial effects of fruits and vegetables in preventing human chronic diseases such as cancer and cardiovascular disease. Increasing fruit and vegetables intakes in individuals can sometimes be difficult and unsustainable, therefore, increasing bioavailability may be an effective alternative approach to maximise health outcomes.

A notable number of vegetables are rich sources of carotenoids, however, the amounts available to the human body for metabolism are often small due to poor bioavailability. For instance, studies have shown that bioavailability of carotenoids from carrots and tomatoes can be as low as 1-3%. The bioavailability of carotenoids has been shown to depend on factors such as their source, degree of cooking, processing, mechanical breakdown, presence of fat and interactions between carotenoids. Whilst the presence of fat significantly increases carotenoid absorption, the oil type, quantity and form it is in all affect bioavailability.

Recent work suggests that carotenoid bioavailability improves when fat is present in the form of mayonnaise rather than as plain oil. This may be due to the emulsion properties of mayonnaise which allows better solubilisation of amphiphilic compounds such as carotenoids. Mayonnaise has also been shown to be more miscible in gastric juices (compared to plain oil) and this too may be contributing to the greater absorption of carotenoids.

The present study builds upon this previous work and studies carotenoid bioavailability in processed food systems. Using a bread-mayonnaise meal the study compares carotenoid bioavailability when it is incorporated either into the bread or the mayonnaise. Furthermore, the study investigates the impact of mayonnaise on the bioavailability of carotenoids incorporated into a processed food (bread). The study will focus on the bioavailability of three principle carotenoids found in foods, alpha-carotene, beta-carotene and lycopene. Carrot and tomato are used as the sources of carotenoids.

HYPOTHESIS Carotenoid bioavailability is influenced by the food matrix in which they are contained.

OBJECTIVES

1. To compare the acute-phase bioavailability (systemic and gut absorption) of targeted carotenoids (alpha-carotene, beta-carotene and lycopene) when they are incorporated into the different processed food matrices (bread and mayonnaise)
2. Study how mayonnaise affects the acute bioavailability of carotenoids incorporated into a processed food.

Eligibility Criteria:
Inclusion Criteria:

* Healthy males and females Aged between 18 and 75 years. Body mass index between 18.5 - 40 kg/m2. Blood pressure equal to or less than 139/89 mmHG. HbA1C less than or equal to 6.5%. Total blood cholesterol less than 6.0mmol/l

Exclusion Criteria:

* Suffering from Diabetes, kidney disease, hepatic disease, gout, gastrointestinal disorder, thromboembolic or coagulation disease, hypertension, thyroid disorder or hypercholesterolaemia On prescription medications Orlistat, Digoxin, Anti-arrhythmics, tricyclic anti-depressants, neuroleptics, oral anti-diabetic medication, insulin, anti-inflammatories, anti-pyretics and Statins Allergic/Intolerant to any of the foods in the study Vegetarian or Vegan Restricted eating and/or eating disorders Alcohol and/or substance abuse Regularly take nutritional supplements (once a day) Smoking Poor venous access and veins difficult to cannulate