15 Best Multivitamins for Adults — Ranked by Ingredients and Value

11. Vitamin D and K2 - The Bone Health Power Couple

The synergistic relationship between vitamin D and vitamin K2 represents one of the most important yet frequently overlooked aspects of multivitamin formulation, as these nutrients work together to optimize calcium metabolism and support both bone health and cardiovascular function in ways that neither can achieve alone. Vitamin D enhances calcium absorption from the digestive tract, potentially increasing blood calcium levels, while vitamin K2 activates proteins that direct this calcium to bones and teeth rather than allowing it to accumulate in soft tissues like arteries and kidneys where it can cause significant health problems. This partnership becomes particularly crucial as adults age and face increased risks of both osteoporosis and cardiovascular disease, conditions that can be exacerbated by calcium supplementation without adequate K2 to ensure proper calcium utilization. The highest-quality multivitamins recognize this relationship by including both nutrients in appropriate ratios, typically providing vitamin D3 (cholecalciferol) rather than the less effective D2 form, alongside vitamin K2 in the MK-7 form which has superior bioavailability and longer half-life compared to MK-4. Many adults have suboptimal vitamin D status due to limited sun exposure and dietary sources, while vitamin K2 deficiency is even more common since this nutrient is found primarily in fermented foods and organ meats that are rarely consumed in modern Western diets. The dosage considerations