Vitamin D is a collection of forms of a pro-hormone fat-soluble nutrient. A crucial element in many reactions and processes in the body, there is a well-reported and well-documented widespread deficiency in Vitamin D. This deficiency is due to several factors including lack of exposure to direct sunlight and an imbalanced diet that provides poor nutrients. Many are caught in a Catch-22 scenario of having a condition caused by a Vitamin D deficiency that is now blocking the body's strategies for synthesizing more. Any Vitamin D is acquired through food, exposure to sunlight and supplements but these forms are inactive until converted into its bioactive form, 25-hydroxy vitamin D, through an enzymatic process in the liver and kidneys. Almost every cell in the body has receptor sites for this converted form of Vitamin D but there are conditions limiting this conversion. People with fat malabsorption, toxicity syndrome, inflammatory condition (including obesity), or impaired liver/kidney function (often caused by painkillers like NSAIDS to relieve inflammation abetted by a lack of Vitamin D) are unable to convert Vitamin D into its bioactive form.

By assessing the specific imbalance in the body and determining the patient's actual need for D supplementation through a serum blood test, a strategy of diet, lifestyle and D supplements can be implemented. Vitamin D promotes bone mineralization and remodeling by enhancing intestinal absorption of calcium and phosphorus, boosting calcium and phosphorus reabsorption in the kidney, and regulating their levels in serum. In addition to supporting bone health, vitamin D also helps modulate inflammation, insulin sensitivity, and immune function (possibly by working in tandem with insulin and cortisol). Additional vitamin D benefits suggested by clinical research include direct anti-viral activity, improved balance and reduction of falls in the elderly, and inhibition of uncontrolled cell proliferation.

Vitamin K is a fat soluble vitamin stored in fat tissues and the liver. Research suggests vitamin K plays a strong role in supporting bone and vascular health due to its synergistic relationship with calcium and vitamin D. This relationship can be summarized as follows: Vitamin D helps boost calcium levels in the blood by enhancing its intestinal absorption and kidney reabsorption; vitamin K helps guide circulating calcium into bone tissue. Vitamin K operates as a cofactor in the carboxylation of specific glutamic acid proteins osteocalcin and matrix GLA protein and without sufficient Vitamin K these proteins never undergo the complete chemical process and calcium is deposited into soft tissues (such as blood vessel walls) instead of bone tissue, where it is most needed by the body.

Vitamin K has numerous forms although it is possibly best known as the shot given to newborns in the hospital. Vitamin K1 (phylloquinone) occurs naturally in plants and the vegetables with highest content are parsley, kale and broccoli. A two-year randomized control found that supplementing with K1 and Vitamin D3 plus calcium noted a significant increase in bone mineral density in older women. K1 is not innate in our bodies as is Vitamin K2, produced from the bacteria in our intestines; infants do not have the ability to produce it right away (thus the hospital shot.) A food product found in daily use by ancient and contemporary traditional cultures is an external source of Vitamin K2 - fermented foods such as kimchi, sauerkraut, and cheese. These dishes bestow a national or cultural identity, no one but Iceland locals would dare eat Hakarl, shark buried in the sand and fermented for months. Fermented foods are the stuff of legends; consider Japan's dish Natto, made from fermented soybeans that is believed to be created by an 11thcentury Samurai warrior. These fermented foods are a way of ensuring proper health in climates or seasons prohibitive of year round fruit and vegetable cultivation.

Moss Nutrition's Vitamin D + K 5000 contains both forms of Vitamin K (Vitamin K1 and K2).