Protein-Prebiotic Wellbeing Study

Healthy participants with self-reported GI complaints will consume the protein supplement that they normally use for recovery purposes after exercise during a 3-week baseline period, followed by a 3-week intervention period in which they maintain usage of their product, but replace a part of this product with a fermented dairy protein with prebiotic fiber. In addition, a group of healthy participants without self-reported GI complaints will serve as a reference group by consuming the protein supplement that they normally use for recovery purposes after exercise during a 3-week period.

A substantial number of athletes suffer from gastro-intestinal problems, which may impair performance and/or subsequent recovery. Also, gut barrier integrity is impaired with high-intensity training. Emerging studies are showing a positive correlation between the gut microbiome and muscle function, athletic performance, body composition, and natural energy levels. This study will perform an exploratory analysis of the well-being and digestive health of well-trained athletes, and assess the potential effect of fermented dairy protein with prebiotic fiber on these parameters.

Question 1: Does the 3-week supplementation of a fermented dairy protein with prebiotic fiber affect the self-reported digestive comfort compared to a 3-week baseline period? And additionally, will the quality of life (self-reported general well-being and states of mood) change with the use of this type of product?

Question 2: Does the 3-week supplementation of a fermented dairy protein with prebiotic fiber show an alteration in gut microbiota in comparison to a 3-week baseline period, while dietary intake remains unaffected?

Question 3: How is the 3-week supplementation of a fermented dairy protein with prebiotic fiber experienced by the participants (taste and concept liking)?

Question 4: Is there a difference in baseline gut microbiota between athletes with and athletes without self-reported GI complaints.

Eligibility Criteria:
Inclusion Criteria:

* Healthy subjects living in Arizona in the USA
* Women/Men aged between 18-35 years
* Serious athletes (exercise at least 3 x per week)
* With or without GI tract issues due to sport or protein/diet intake
* 18.5 ≤ BMI ≤ 40 kg/m2
* No physical limitations (i.e. able to perform all activities associated with daily living in an independent manner).
* Use of a protein supplement or sports food after at least one training per day 3 x per week
* Willing to slightly increase their protein supplement intake during the intervention phase for 21 consecutive days
* Stable weight during the last 4 weeks, without a focus on body weight reduction through limiting caloric intake
* Written informed consent

Exclusion Criteria:

* Daily use of (sport) supplements containing probiotics and/or prebiotics
* Smoking
* Self-reported cow's milk protein allergy
* Clinical lactose intolerance
* Clinical milk protein allergy
* House dust mite allergy
* Diagnosed GI tract disorders or diseases
* Musculoskeletal disorders
* Metabolic disorders (such as diabetes)
* Use of any medications known to affect protein metabolism (i.e. corticosteroids, non-steroidal anti-inflammatories, or prescribed acne medications).
* Chronic use of gastric acid-suppressing medication or anti-coagulants
* Use of antibiotics or anti-inflammatory medication the past 2 weeks
* Blood donation in the past 2 months
* Pregnant/lactating women
* Athletes should not aim to lose body weight by reducing energy intake during the study