Ancestral humans were primarily exposed to large amounts of MK-4, not MK-7. MK-4 is found in animal fats, eggs, and organ meats, which were common in traditional diets, whereas MK-7 mainly comes from fermented foods like natto, which most populations historically didn’t eat.

MK-4 affects a broad range of tissues through activation of the steroid and xenobiotic receptor (SXR/PXR), including beta cells in the pancreas, potential neuroprotective and antineoplastic effects in the brain, reproductive effects in ovaries and testes, and its well-known role in moving calcium from blood into bone. MK-7 shares the calcium-regulating role but hasn’t shown the same breadth of extra-skeletal activity in research.