Not all kosher foods are gluten-free, but there is no shortage of notable gluten-free companies with kosher certification. Gluten is a protein found in flour and products made from wheat, barley, rye, spelt, and some varieties of oats.
This was once a niche claim aimed at people with celiac disease or gluten allergies, who had to shop at specialist stores to get products and ingredients suitable for their needs. Over the years, spikes in interest for gluten-free has coincided with consumers aligning themselves with healthy eating, clean eating, and the rising popularity of grain-free/low carb diets like paleo and keto.
Kosher certified foods are foods that contain only kosher ingredients. The two certifications are not connected, but both belong to an ever-growing specialty food trend especially in the health food industry.
The popular trend in gluten-free has a similar hue to the thriving demand for kosher certification. Only 1% of the world population is diagnosed with Celiac Disease (the disorder which causes gluten related autoimmune symptoms) but gluten-free labels are mentioned on 10% of new food and drink launches in the US.