Broccoli has the precursor of an active compound (sulforaphane) that has shown a wide range of health promoting benefits. Sulforaphane formation depends on the conversion of glucoraphanin (precursor) by myrosinase enzyme. Thus, the bioavailability of sulforaphane is affected by myrosinase activity. Some bacteria, such as L. plantarum (probiotic), have shown they can also convert glucoraphanin to sulforaphane in vitro. This study investigates the effect of short-term L. plantarum supplementation on broccoli sulforaphane bioavailability in humans using a randomised double-blind placebo-controlled crossover trial.

Brassicas (i.e. broccoli, kale, cabbage) are a group of edible plants that contain a phytochemical called glucoraphanin that upon enzymatic hydrolysis forms the bioactive form sulforaphane. Sulforaphane has shown consistent in vitro and in vivo (animals) anti-cancer activity. The enzyme responsible for this conversion is called myrosinase; however, the enzymatic activity of myrosinase can be affected by several biological factors (e.g. plant variety, growth conditions, etc...) and food processing (e.g. cooking, drying, etc...). Broccoli is one of the richest sources of glucoraphanin, but its myrosinase activity can be easily lost during cooking: 10 minutes at 70 °C reduces the enzyme activity by 95%. This means broccoli prepared this way will contain little to no biologically active sulforaphane. Therefore, is important to find strategies to increase the bioavailability of sulforaphane in broccoli and other brassicas for human consumption.

Certain bacteria have shown myrosinase-like activity and were able to convert glucoraphanin to sulforaphane in vitro, one of these bacteria is Lactiplantibacillus plantarum. This bacterium is present in the human gut, however, there is a large biological variability in the prevalence of this bacteria between individuals. Several human studies have demonstrated that chronic (>1 week) consumption of probiotic supplements containing L. plantarum was able to increase the presence of this bacterium in human gut participants. Thus, the investigators aim to test if supplementing participants with L. plantarum will increase the bioavailability of sulforaphane, compared to placebo.

Inclusion Criteria:

• healthy adults (male and female)
• age range of 18-65 years
• BMI range of 18-30 kg/m2

Exclusion Criteria:

• have been on a course of antibiotics within the period of the past 3 months.
• have allergies or intolerance towards probiotic substances or broccoli used in the study and/or food intolerances associated with gastrointestinal upset.
• have been taking pre- or probiotics supplements regularly during the last month prior (this does not include foods containing probiotics and/or prebiotics foods)
• are following any restricting diet (e.g., vegan, FODMAP, etc.).
• have a gastrointestinal inflammatory condition (e.g., irritable bowel syndrome, inflammatory bowel diseases, coeliac diseases, constipation, etc.).
• have a medical condition or take medication for any heart, endocrine, or metabolic condition, such as high blood pressure, high cholesterol, insulin resistance, or diabetes, or autoimmune disease.
• are a pregnant and/or breastfeeding.

Participant details (name, age, sex, etc.) will be stored in a password secured as per university guidelines. Participants will be allocated a code (ID number) at enrolment, and this will be used to refer to them hereafter. Data will be collected and entered under a participant's ID number, and analysed and stored as such. Only researchers listed in this application will have access to all data. Presentations, reports and publications will only include aggregated data with no personal or individual data included. Anonymised databases will be made available upon request or deposit in open repository upon request of journal.