Are Blueberries Keto?

Although blueberries are low in carbs, they are in the middle of the spectrum. You can find lower carb berries such as raspberries and blackberries which have around half the amount of net carbs as blueberries.

A single serving of blueberries is 50 berries weighing around 68 grams. Approximately 84% is water and this serving has 35 kcal of calories.

A serving of blueberries (68g) contains approximately 6 grams net carbs. Total carbohydrates are 8 grams with 4 grams of fructose and 2 grams of fiber.

Blueberries are a good source of Vitamin C, Vitamin K and Manganese. Also blueberries contain anthocyanins, which is the pigment that makes blueberries blue and are found in other vegetables as well. Anthocyanins are an antioxidant which have been studies to have a potential for a wide variety of health benefits, although they have been difficult to study with regards to human health and most of these benefits have been found with in vitro (outside of the human body) experiments and mouse studies.

If your goals are weight loss using the ketogenic diet, blueberries will be a good tool especially in the beginning to help improve energy levels while transitioning to a fat based metabolism. The best way to have them would be to have them after your meals which will slow down the absorption minimizing the insulin effect and keep the amount to a single serving.

Fructose found in all fruits is used as a signal in the liver to store fat. However, according to studies on mice and humans, under 5 grams of fructose in a single meal will all be metabolized in the small intestine into glucose and won’t reach the liver, therefore does not trigger this effect (r). A single serving of blueberries with only 4 grams of fructose won’t trigger this effect.

When you eat blueberries for your workouts will change the insulinogenic effect of the food on your body. To minimize the release of insulin while eating carbs on a ketogenic diet, ideally you would eat them post workout since your body will be the most insulin sensitive allowing your muscles to quickly uptake sugars to refill your glycogen stores with the minimal amount of insulin.

If you want the energy for the workout, then eating them an hour before your workout will allow the carbohydrates to be available during the exercise.

In a randomized control trial done on humans in 2018 found that participants with mild cognitive impairment had improved neural activation when supplemented with blueberries compared to placebo group (r). In this trial, they used whole fruit freeze dried blueberry powder so it was whole food form that was tested and not isolated compounds.

A mouse study found that anthocyanins found in blueberries protected the retinas of the mice from oxidative stress caused by diabetes (r). This is a study on animals so it may not be the same in humans, but provide a hypothesis of possibility for further research.

Blueberries are a good and healthy choice to eat on a keto diet which can help supplement some additional energy from carbohydrates when needed or for a treat.

You can minimize the effect it has on blood sugar and insulin by eating them after a meal, having them before or after exercise and keeping the serving size low.