Pilot Haskap Metabolite Timing Project

Haskap berries (Lonicera caerulea L.), also known as Blue Honeysuckle or Honeyberry, are a polyphenol rich berry that has a greater polyphenolic content than other commonly consumed berries, like strawberries or blueberries. Haskap berries are unique, having a greater content of polyphenols compared to other foods, specifically cyanidin-3-glucoside. Cyanidin-3-glucoside is an anthocyanin shown to reduce inflammation and cardioprotective effects. There is a growing body of literature describing the impact of berry consumption on metabolic health; however, Haskap berry specific investigations in human participants are limited. Currently, Haskap berry consumption shows promising findings in research related to glycemic control, oxidative stress, and inflammation in in-vitro and mice models. The benefits of Haskap berries as a functional food are highly encouraging in animal models, but translational research to demonstrate beneficial health impacts in humans is needed.

A crucial aspect of polyphenol metabolism is the role of the gut microbiome, which influences both metabolic responses to polyphenol consumption and the bioavailability of polyphenolic metabolites. Polyphenol digestion differs based on the structure of the polyphenol and what area of digestive tract is being considered. In the mouth, mastication and salivary enzymes begin the digestion process. However, polyphenols bind with salivary proteins, like tannin-binding salivary proteins, that inhibit their breakdown and subsequent absorption. In the stomach, a limited amount of polyphenols are broken down and/or absorbed and other are conjugated with glucuronic acid. In the small intestine, polyphenols are hydrolyzed into smaller subunits to be absorbed by both passive and active transport. Lastly, the large intestine is the most important segment of digestion to consider.

One of the challenges of polyphenolic research is the intricate relationship between the gut microbiota and the absorption of polyphenolic compounds. Bacteria in the gut are responsible for the majority of polyphenol digestion. Bacteria in the gut interact with polyphenols in a variety of biotransformation reactions including esterification, dehydroxylation, reduction, and decarboxylation. Certain bacteria in the gut have the ability to perform these reactions with polyphenols, including but not limited to Flavonifractor plautii and Bifidobacterium spp. Polyphenol consumption has been shown to modulate microbial composition; however, this project aims to understand how the microbiome impacts metabolite abundance.

This project aims to bridge an important gap that is how the gut microbiome impacts dietary polyphenol absorption and metabolism and how this impacts the health-promoting compounds in Haskap berries. The purpose of this research proposal is to investigate how the microbiome impacts metabolism of polyphenols from Haskap berries. Overarching hypothesis: The composition of bacteria in the gut of participants will impact the Haskap-related metabolites produced

Inclusion criteria

• 18-45 years old
• Body mass index (BMI) between 18-30 kg/m^2

Exclusion criteria

• allergy to Haskap berries
• have taken antibiotics in the last 90 days
• take dietary supplements
• have adverse events from blood draws
• take medication to lower cholesterol, inflammation, lipids
• smoke cigarettes
• pregnant and/or lactating
• have diabetes
• are unwilling to follow a no-polyphenolic diet for 10 days