In Gut and Physiology Syndrome, Dr. Natasha Campbell-McBride discusses vitamin K2 separately for breastfed and bottle-fed babies. A breastfed baby receives K2 through the mother’s milk when the mother is not deficient in fat-soluble vitamins. A bottle-fed baby may be deficient, so the book names good-quality cod liver oil for vitamins A and D and butter oil for K2 as its preferred supplement combination.[1]
The word may matters: the book does not say every bottle-fed baby is deficient. It names butter oil specifically, rather than ordinary butter or ghee, and gives no infant dose, starting age or supplement schedule in this passage. For the wider pregnancy and feeding plan, begin with my GAPS preparation guide.
Why Vitamin K2 Matters for Bone Mineralization
The GAPS book describes K2 as essential for bone mineralization. Vitamin D helps calcium and other minerals settle into bone, while K2 belongs to the wider fat-soluble-vitamin pattern that helps the body use minerals properly.[1]
Supporting research helps explain that biochemical step. In a randomized trial of healthy prepubertal children, eight weeks of MK-7, a form of vitamin K2, increased circulating MK-7 and improved osteocalcin carboxylation, a chemical step that helps activate this protein. Osteocalcin is one of the vitamin-K-dependent proteins involved in bone metabolism.[2] The children’s trial examined a bone-metabolism marker; it did not test an infant dosing schedule.
The Gut Flora Source of K2
Gut and Physiology Syndrome places gut flora at the center of K2 status. It says gut microbes synthesize K2 and describes the gut flora as the main, and sometimes only, source of this vitamin for the body. Fermented foods can provide K2 while the long-term work is restoring the microbial community that produces it.[3]
This is one reason the infant question cannot be reduced to a calcium label. The book’s K2 discussion connects the vitamin with food, maternal status, milk, and the baby’s developing gut flora. My baby gut flora guide explains how pregnancy, birth, breast milk, and early feeding fit together.
Food Sources That Fit Full GAPS
The book names high-fat animal foods and fermented foods as K2 sources. It uses well-aged, traditional high-fat cheese as a Western example and natto as an Eastern example.[1]
That does not make natto a Full GAPS food. Natto is fermented soy, and the official Full GAPS avoid list excludes soy.[4] For a GAPS reader, the useful source categories are the GAPS-compatible high-fat animal foods and fermented foods the person tolerates. The 2020 book says to avoid soy in every form for the first few years of GAPS. It allows traditional soy products to be introduced slowly only after full recovery.[7]
Vitamin K2 in Breast Milk
The source says a breastfed baby receives K2 through the mother’s milk if the mother is not deficient in fat-soluble vitamins.[1] The conditional phrase matters. Breastfeeding is the route, while the mother’s own status affects what is available through that route.
A human milk study provides support for that transfer. The researchers found that MK-4, another form of vitamin K2, accumulated in breast milk and that maternal MK-4 administration increased its concentration in milk.[5] That finding helps explain how maternal K2 can reach breast milk. The food and supplement recommendations here come from Dr. Natasha’s book.
The everyday GAPS food structure for a nursing mother lives in my Full GAPS while breastfeeding guide. For the wider comparison, read Breast Milk vs. Formula on GAPS: What the Sources Describe.
What the Book Says About Bottle-Fed Babies
The exact sentence in the 2020 book says bottle-fed babies may be deficient in K2 and that steps should be taken to provide it. It then names good-quality cod liver oil for vitamins A and D and butter oil for K2 as the best policy.[1]
| The Passage Says | The Passage Does Not Specify |
|---|---|
| Bottle-fed babies may be deficient in K2. | It does not say every bottle-fed baby is deficient. |
| Cod liver oil supplies vitamins A and D in this combination. | It does not give a dose, starting age, frequency, or brand in this section. |
| Butter oil supplies K2 in this combination. | It does not say ordinary butter or ghee is interchangeable with butter oil. |
| The two oils are the book’s preferred policy for this route. | It does not provide a self-adjusting infant schedule. |
If bottle feeding is happening because breast milk is unavailable, the K2 passage is only one piece of the GAPS feeding framework. Wet Nursing and Donor Milk in GAPS: A Complete Guide explains the source’s preferred milk fallback, donor criteria, and handling distinctions. The K2 passage addresses one part of that wider feeding question.
How We Use These Oils in Our Family
Our family uses Green Pasture fermented cod liver oil and butter oil in different forms, depending on who is taking them and what they are having them with. I have nursed for almost six years straight, and our family began GAPS in July 2024.[6]
You can read about the forms we use in my Green Pasture review. That family use is separate from the bottle-fed baby’s K2 recommendation above; I do not have an infant K2 test result or an outcome from that feeding situation to share.
When Solid Food Begins
Once a baby is ready for solids, food sources can begin entering the picture through the Baby GAPS sequence. A food’s K2 content does not determine when it enters the Baby GAPS sequence. When to Start Solids on GAPS: Breastfed and Bottle-Fed Timelines establishes when the feeding transition begins, and Baby GAPS: First Foods and the Week-by-Week Weaning Plan keeps each food in its actual order.
A Full GAPS Plan for Nursing Mothers
My Nursing Mama on Full GAPS course is a practical next step for building complete meals around meat stock, animal fats, organ meats, fermented foods, and enough food for the mother. It covers the breastfeeding route in this article.
Frequently Asked Questions
Does GAPS Say Every Bottle-Fed Baby Is K2 Deficient?
No. The wording is that bottle-fed babies may be deficient. That is why the book discusses it as a possibility.
Is Breastfeeding Alone a Guarantee of Adequate K2?
The book makes the route conditional. It says the baby receives K2 from the mother’s milk if the mother is not deficient in fat-soluble vitamins.
Does the Book Give a Standalone K2 Schedule for the Mother?
Not in these passages. It names gut flora, high-fat animal foods, and fermented foods as K2 sources, then gives the cod-liver-oil-and-butter-oil combination for the bottle-fed route. The GAPS passages used for this article do not give a universal standalone K2 schedule for a breastfeeding mother.
Can I Replace Butter Oil With Butter or Ghee?
The infant passage names butter oil. It does not state that ordinary butter or ghee is an equivalent substitute in this supplement combination.
Is Natto a GAPS K2 Food?
No. The book lists natto as a general example of a K2-rich fermented food, but the official Full GAPS list excludes soy. The later-recovery distinction is explained above; it does not make natto part of the active Full GAPS food list.
References
- Campbell-McBride, N. Gut and Physiology Syndrome (2020), “Bones and Teeth,” vitamin K2, breastfeeding, bottle feeding, cod liver oil, and butter oil.
- van Summeren, M. J. H., et al. “The Effect of Menaquinone-7 (Vitamin K2) Supplementation on Osteocalcin Carboxylation in Healthy Prepubertal Children.” British Journal of Nutrition 102, no. 8 (2009): 1171–1178. PMID 19450370.
- Campbell-McBride, N. Gut and Physiology Syndrome (2020), “Production of Vitamins and Hormones,” gut flora and vitamin K2.
- GAPS Diet / International Nutrition. “Full GAPS Diet,” official allowed- and avoid-food list.
- Saga, K., and T. Terao. “Studies on Transfer of Vitamin K Into Human Breast Milk.” Nihon Sanka Fujinka Gakkai Zasshi 41, no. 11 (1989): 1713–1719. PMID 2592801.
- Garnica, Ebonie. My nursing and postpartum family account and my Green Pasture review.
- Campbell-McBride, Natasha. Gut and Physiology Syndrome (2020), “No Soya, please!”
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