The Gut Reset Smoothie
with kefir, ground flaxseed and berries
By Superfoods Advisor Editors·July 4, 2026
Allergens Milk
Ingredients
¾ cupPlain whole-milk kefir
1 tbspGround flaxseedGround absorbs far better than whole
1 wholeRipe banana, frozen
¼ cupFrozen raspberries
¼ cupFrozen strawberries, slicedBlackberries work equally well here
¼ cupPlain Greek yogurtNonfat; whole-milk yogurt adds about 3 g fat and 25 kcal- ½ cupCold water
From your pantry
- 1 pinchGround cinnamon
Utensils Blender
Instructions
Peel and freeze the banana the night before. Frozen fruit gives the smoothie its body without watering it down.
Pour the kefir and cold water into the blender, liquid first.
Add the Greek yogurt, then the frozen banana and berries. Scatter the ground flaxseed and cinnamon over the top so they meet liquid rather than caking on the blade.
Blend for 30 to 45 seconds. Do not over-blend: friction heat can reduce the number of viable cultures.
Drink it fresh, straight after blending.
Shopping list
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Tools
Why it works
Using ground rather than whole flaxseed matters. The hull of a whole flaxseed is largely indigestible, and grinding it makes both the omega-3 ALA and the lignans more available: milled flaxseed raised plasma ALA while whole seed did not (Austria et al., Journal of the American College of Nutrition, 2008, PubMed:18689552), and ground seed gave higher blood enterolignan levels than whole seed (Kuijsten et al., The Journal of Nutrition, 2005, PubMed:16317125). Flaxseed lignans are converted by gut bacteria into enterolignans, which were associated with higher levels of sex hormone binding globulin in a small observational study of 30 postmenopausal women, alongside supporting cell-culture work (Adlercreutz et al., The Journal of Steroid Biochemistry and Molecular Biology, 1992, PubMed:1314077). Kefir contributes live cultures, which heat-treated fermented products no longer contain.
A 2019 review of 45 trials in healthy adults (Khalesi et al., European Journal of Clinical Nutrition, PubMed:29581563) found that probiotics produced transient increases in the supplemented bacteria and some improvements in stool consistency and bowel movements, but no persistent change in gut microbiota. Those trials mostly tested probiotic supplements rather than kefir itself. Pairing kefir with the gel-forming fibre from flaxseed is meant to cover both the bacterial and the bulk-forming side of gut function, though no trial has tested the combination.
Macro detail: the 28 g of sugar is almost entirely lactose from the kefir and yogurt plus fruit sugars; nothing is added.
This recipe is part of 5 Superfood Smoothie Recipes Backed by Nutritional Science, which covers the underlying nutrition science and the shared base method.
