Is San francisco sourdough style starter culture Keto?

The Ingredient Breakdown

As a food scientist, I look at the biological composition of ingredients rather than just the marketing claims. The verdict here is straightforward because the ingredient list is transparent. The primary component of this starter is White flour and Wheat flour.

Regardless of the fermentation process, which may lower the glycemic index slightly, the flour itself is composed almost entirely of starch (glucose chains). When you feed a starter culture, you are essentially keeping a colony of yeast and bacteria alive on this starch. Even a small amount of residue or a tablespoon of the starter itself contains enough carbohydrates to spike insulin and knock you out of ketosis. Additionally, the product is manufactured in a facility that processes products containing gluten, posing a risk for those with Celiac disease or severe gluten sensitivity.

Nutritional Value

From a nutritional standpoint, this starter culture is a high-carbohydrate source. While the live active cultures (probiotics) are beneficial for gut health, they do not negate the macronutrient profile of the flour substrate. A single serving of flour contains roughly 20 to 25 grams of net carbohydrates, which is often the entire daily allowance for a strict Keto diet. There is negligible fat or protein in the starter culture itself to balance out the glucose load. Therefore, it does not fit within the dietary limits of a ketogenic lifestyle, which typically restricts net carbs to under 20-50 grams per day.