Bone & Heart Support

Both vitamins D3 and K2 are essential to the body's function and overall health. Vitamin D3 aids in absorbing calcium and phosphorus, which are essential for bone formation and maintenance.

Stress fractures are the most common serious injury in distance runners, and bone density is built or lost incrementally with every training block -- vitamin D3 + K2 for runners supplies two of the core micronutrients that determine whether bone remodeling keeps pace with training load.

In addition to supporting the development of strong bones, Vitamin K2 may also benefit the cardiovascular system since it may promote healthy blood clotting.*

Ingredients: Calcium (as Calcium Carbonate), Vitamin D3 (Cholecalciferol), Vitamin K2 (mk-7)(as Menaquinone), BioPerine® (Black Pepper Fruit Extract), Microcrystalline Cellulose, Hypromellose (vegetable capsule).

Manufacturer Country: USA

Product Amount: 60 caps

Gross Weight: 0.16lb (73g)

Suggested Use: Take one (1) capsule twice a day as a dietary supplement. For best results, take 20-30 min before a meal or as directed by your healthcare professional.

Caution: Do not exceed recommended dose. Pregnant or nursing mothers, children under the age of 18, and individuals with a known medical condition should consult a physician before using this or any dietary supplement.

Warning: Keep out of reach of children. Do not use if the safety seal is damaged or missing. Store in a cool, dry place.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

FAQ

Q: Do runners need vitamin D3 supplementation if they already train outdoors?

A: Outdoor training does not guarantee adequate D3 status. Endogenous D3 synthesis requires UVB at sufficient intensity, which drops sharply in winter months above 35 degrees latitude, during early morning runs, and when training in full-length clothing. Studies in endurance athletes show D3 insufficiency (serum 25(OH)D below 30 ng/mL) in 30--56% of those tested, including year-round outdoor athletes. Supplementation provides reliable, measurable intake regardless of season or training schedule.

Q: Why does vitamin K2 matter if D3 is already increasing calcium absorption?

A: D3 increases calcium absorption but does not control where that calcium goes. Without K2, absorbed calcium has no reliable routing mechanism to bone. K2 (MK-7 form) activates osteocalcin, which incorporates calcium into bone matrix, and activates MGP, which prevents calcium from accumulating in soft tissue. D3 and K2 work together: D3 drives uptake; K2 determines the destination. Taking D3 without K2 addresses only half of the bone-density equation.

Q: Is this product relevant for female runners specifically?

A: Female runners are at disproportionate risk of stress fractures, particularly those with low energy availability, irregular menstrual cycles, or a history of RED-S (Relative Energy Deficiency in Sport). Adequate D3 and K2 status supports bone remodeling during high training loads and helps maintain bone mineral density during hormonal fluctuations. For perimenopausal and menopausal runners, where estrogen-driven bone protection declines, D3 + K2 is especially relevant to a daily supplement protocol.

Q: What is the difference between K2 MK-4 and K2 MK-7, and why does it matter for runners?

A: MK-7 (the form in this product) has a half-life of approximately 72 hours in the bloodstream versus 1--2 hours for MK-4. This means MK-7 maintains active K2 levels throughout the day from a once- or twice-daily dose, while MK-4 requires more frequent dosing to sustain osteocalcin and MGP carboxylation. For runners who take supplements around training and meals rather than at fixed clinical intervals, MK-7 provides more consistent coverage without multiple daily doses.