Probiotics, vitamin K and calcification
Vitamin K is made with the help of probiotics and our 'good guy' intestinal bacteria. Adequate vitamin K may help prevent calcification of soft tissue and potentially reduce the risk for heart disease and some types of cancer. Healthy intestinal bacteria can make vitamin K in a form that is well absorbed compared to the form found in vegetables and a few other foods.Vitamin K1 is more common in the diet in many green vegetables but it is poorly absorbed. Vitamin K2 is found in foods made with active bacterial cultures like yogurt, sauerkraut, kim chee and some cheeses.
The richest food sources of vitamin K include green leafy vegetables like spinach, kale, Brussels sprouts and broccoli. It is also found in small amounts in egg yolk, some meats, flatfish and eel. Dairy products like yogurt or cottage cheese may contain vitamin K as a side product of the active cultures. Natto, miso, tempeh, kim chee and other live cultured products may also be a source of vitamin K depending on the type of bacteria used in processing. Sauerkraut and dill pickles sold from a refrigerated case may be a source of the live 'good guy' bacteria. The fermented products provide some vitamin K and provide the good guy bacteria that can keep making more vitamin K while protecting against yeast and less friendly bacteria. Spoilage does occur with live products. Food safety guidelines and 'use by dates' should be followed.  
Probiotic supplements are also available that are designed to provide some of the good guy bacteria in a capsule. Check the source for quality control standards and storage recommendations.
Vitamin K helps the body make the hormone, osteocalcin, which helps signal calcium to enter bone tissue  and is important for regulating blood sugar levels. Adequate vitamin K helps the calcium stay in the bone tissue and reduces the risk of soft tissue calcification. Hardening of the breasts may not lead to heart attacks, a risk with arteriosclerosis, or the hardening of arteries from calcium/cholesterol deposits, [9, 10] but the condition isn't likely to be comfortable either. Calcium is electrically active inside of the cell and can signal membranes to break down. Calcium deposits in soft tissue may be enclosed in fatty cholesterol deposits to help prevent the risk of inflammatory membrane break down.
Vitamin K is essential for blood to clot but it is also very important for preventing calcification of soft tissue. Calcium deposits add to hardening of the arteries or arteriosclerosis but abnormal calcification is also seen in some cases of breast cancer.  Calcification of soft tissue becomes more common in people over 50 and is frequently considered a normal part of aging. However soft tissue calcification can be a symptom of excess vitamin D intake and can be a symptom of vitamin K or magnesium deficiencies.
A study found less incidence of prostate and lung cancer in participants who reported more intake of vitamin K foods. The link with breast or colon cancer was less clear but the study was based on self reported intake of common foods and cheese was the richest food source of vitamin K reported (cheese is also a source of calcium). None of the study participants had an estimated intake of vitamin K that met the RDA. In the U.S. 120 mcg is recommended for men and 90 mcg for women. In the study 24,340 adults were followed for ten years and averaged less than 100 mcg/day.  A cup of carrots has about 15 mcg, a cup of kale has 1054 mcg (but the form is not well absorbed) and a cup of sauerkraut has 81 mcg. 
Bacteroides is a family of bacteria that are commonly found in the intestines. Some helpful bacteria are known to make vitamin K. Some of the Bacteoides family are more helpful to health than others. Having a variety of bacteria in the intestines can reduce the growth of other more deadly bacteria and helps prevent excessive yeast growth. Intestinal health is not a pleasant topic but intestinal ill health is even less pleasant.
A study about celiac disease risk tested for types of Bacteroides species in newborns. A difference in intestinal species was noted based on the genetic differences between the infants and whether they were fed with human milk or commercial infant formula. Infants without the high risk genotype and infants receiving human milk feedings had more of the healthier species of Bacteriodes.  This suggests that some infants and people may be more at risk than others for intestinal imbalance which can result in poor nutrient absorption and deficiencies. Probiotics from foods or supplements could be helpful as part of the daily diet.
Probiotic supplements can not supply all types of healthy bacteria in a shelf stable form. Freshly prepared fermented foods may be a better source of some types of the healthy bacteria.  Kefir is a type of active culture beverage that is made from milk similar to the way that yogurt is made. Infant formula possibly could be prepared with the healthy Bacteroides species to help establish healthy digestion and vitamin K. Kefir and other active culture products spoil more rapidly so food safety risks would need to be tested with any new products. Infants typically are given supplemental vitamin K at birth because there is little found in the breast milk. The healthy bacteria that are promoted by the human milk feeding could be providing the vitamin K infants need once the good guy bacteria are established in the intestines of the infant. (unpleasant to think about but healthy for digestion and strong bones).
Digestive issues may be helped by vitamin K and probiotic foods or supplements. And having adequate vitamin K can help prevent calcification of the soft tissue and osteoporosis of the bones. While calcification itself is not proven to be a cause of cancer or heart disease, calcium deposits are found in tumors and in arteriosclerotic plaque which suggests that excess calcium is involved.
Disclaimer: Opinions are my own and the information is provided for educational purposes within the guidelines of fair use. While I am a Registered Dietitian this information is not intended to provide individual health guidance. Please see a health professional for individual health care purposes.
Sanchez E., et.al., "Inﬂuence of Environmental and Genetic Factors Linked to Celiac Disease Risk on Infant Gut Colonization by Bacteroides Species" Applied and Environmental Microbiology, Aug. 2011, p. 5316–5323 pdf: [ncbi.nlm.nih.gov] *an increased prevalence of B. vulgatis was found in infants with the HLA-DQ genotype that is associated with increased risk for developing celiac disease. An increased prevalence of B. uniformis was associated with infants without the high risk genotype and with infants who received breast milk feedings.
Itzhak Brook, "Bacteroides Infection," Medscape.com: [emedicine.medscape.com]
Johnson K., "Breast Calcifications." (last reviewed Oct. 28, 2012) webmd: [women.webmd.com]
Vermeer C., "Vitamin K: the effect on health beyond coagulation an overview." Food & Nutrition Research 2012. 56: 5329 - DOI: 10.3402/fnr.v56i0.5329 pdf, full article: [ncbi.nlm.nih.gov]
Lev M., "Sphingolipid biosynthesis and vitamin K metabolism in Bacteroides melaninogenicus." Am J Clin Nutr. 1979 Jan;32(1):179-86. Full article [ajcn.nutrition.org/content/32/1/179.long] * This link is really about a different topic. Vitamin K may be important for assembling phospholipids that are used in membranes.
King-Nosseir A., "Eating Well: Bones need more than just calcium," (5/16/2012) abqjournal.com: [abqjournal.com]
"Higher vitamin K intake tied to lower cancer risks." (March 31, 2010) Reuters: [reuters.com] *This discusses the results of a large study but the vitamin K intake was based on self reported food intake and cheese was the primary source they mention tracking.
"Vitamin K Content of Common Foods." University Healthcare Thrombosis Service, My Warfarin Therapy, healthcare.utah.edu [healthcare.utah.edu]
"Hardening of the Arteries." (June 3, 2012) pubMed: [ncbi.nlm.nih.gov]
Howenstine J., "Arteriosclerosis Can Be Reversed, Part 1." (7/24/2008) [newswithviews.com]
Cuomo M.I., "A World Without Cancer, The making of a new cure and the real promise of prevention." (2012, Rodale Press, New York) [Amazon] *breast cancer tumors are described as a chalky white that stands out from the surrounding tissue. Diagnostic screening was described that differentiates between abnormal and normal calcification of the breast. ** My position is that calcification of the breast or arteries is abnormal and is related to long term nutrient deficiencies or sometimes parathyroid cancer or other unusual disease rather than being a normal part of aging.
Myhill S., "Probiotics - we should all be taking these all the time and double the dose following antibiotics and gastroenteritis." [drmyhill.co.uk]
"Osteocalcin hormone can regulate glucose levels: Research" (July 23, 2010) [news-medical.net]