Biomarkers of Meats and Potatoes Intake.

The discovery of biomarkers for the intake of meats and potatoes is needed for an accurate assessment of the intake of these foods. Twelve healthy subjects were enrolled in a controlled, cross-over meal study, randomized by a Latin square design. The test meals contained 1) beef, pork, chicken and a control meal for the meats and 2) french fries, boiled potatoes, chips and a control for the potato meals. A standardized diet was provided during sample collection. Blood and urine samples were collected up to 48h primarily for untargeted metabolomic profiling. Blood was further collected to study the effect of the meals on insulin and glycemic responses. Effects on satiety were measured by VAS and an ad libitum lunch following the test meals.

Protein-rich diets improve body weight regulations and are thus believed to play a key role in combating the global obesity epidemic. Protein-rich diets are generally high in meats, some of which have become controverted enough to be considered disease-promoting foods despite their nutritional richness. The degree at which associations with disease differs from causality is however not entirely known.

Assessment of food intake currently relies on food frequency questionnaires (FFQ), 24h recall and dietary records, all of which are self-reporting methods known to be subject to bias and inaccuracy. Biomarkers of food intake emerged thus within the past years to complement the conventional tools as objective measurements of food intake, drawn from biological samples. Several biomarkers of meat consumption have been proposed, however none is currently accepted and used as biomarker(s) of meat intake and none is able to differentiate between the different types of meat.

In the modern diet, meats are very often served with potatoes. To our knowledge, biomarkers of potato intake have not been thoroughly reported in the literature. Different cooking methods were shown to potentially influence the content of bioactive constituents of vegetables, their glycemic index, as well as subsequent energy intake. High heat cooking additionally yields the formation of potentially toxic compounds such as advanced glycation endproducts (AGEs) that were shown to contribute to insulin resistance and type 2 diabetes. In this line, biomarkers of potatoes as such as well as biomarkers to differentiate between different cooking methods would be of great importance in advancing the understanding of nutritional science.

Primary objectives:

1. To identify acute biomarkers of general meat intake by untargeted metabolomics
2. To explore the changes in the metabolome as a result of acute exposure to three types of meat and identify meat-specific biomarkers of intake
3. To identify biomarkers of acute potato intake by untargeted metabolomics
4. To identify biomarkers that can differentiate between three types of cooking methods
5. To investigate the effect of the interaction between meat on potatoes on satiety, assessed by registration of intake from an ad libitum meal

Secondary objectives:

1. To validate already known biomarkers of meat intake by targeted metabolomics
2. To investigate the effect of the interaction between meat and potatoes on satiety, assessed by visual analogue scales
3. To investigate the effect of the interaction between meat and potatoes on glucose and insulin responses

Eligibility Criteria:
Inclusion Criteria:

* BMI \< 30 kg/m2
* Eating and tolerating meat, egg, pea, rice, and potatoes
* No current chronic or infectious disease
* No medication (oral contraceptive pill and mild antidepressants is allowed)
* No dietary supplements
* Did not use antibiotics in the 6 previous months

Exclusion Criteria:

* Any condition that makes the project responsible researcher to doubt the feasibility of the volunteer's participation
* Pregnant or lactating women
* Smoking (12 months of non-smoking is allowed)
* Vegan or vegetarian
* Have or have had a drug addiction
* Blood donations within three months before participating in the current trial or participation in other scientific experiments
* Alcohol consumption higher than the Danish Health Authority recommendation of 7 or 14 drinks/week for women and men, respectively.