Vitamin K1, D3 & Calcium for Stronger Bones?

randomized-controlled-trial PMID: 17243866

Quick Summary: A study found that older women who took vitamin K1, vitamin D3, and calcium together saw a small but positive boost in bone health, specifically in their wrists. This suggests a possible benefit for bone strength.

Does Vitamin K1 Help Bone Health?

This research looked at how vitamin K1 (also called phylloquinone) affects bone health in older women. The study found that taking vitamin K1 along with vitamin D3 and calcium could improve bone mineral content (BMC) and bone mineral density (BMD) in the wrist.

What The Research Found

Combined Benefit: Women taking vitamin K1, vitamin D3, and calcium together showed improved bone health in their wrists.

Vitamin K1 Alone: Vitamin K1 alone seemed to help the body use calcium better, which is important for bone health.

Other Findings: The study also showed that vitamin D3 and calcium levels increased in the blood of those taking the supplements.

Study Details

Who was studied: 244 healthy women over 60 years old.

How long: The study lasted for 2 years.

What they took:

Some women took a placebo (a "dummy" pill).
Some took 200 mcg of vitamin K1 daily.
Some took vitamin D3 (400 IU) and 1000 mg of calcium daily.
Some took vitamin K1, vitamin D3, and calcium together.

What This Means For You

Consider Your Diet: Eating foods rich in vitamin K1 (like leafy green vegetables) may support bone health.

Talk to Your Doctor: If you're concerned about bone health, discuss vitamin K1, vitamin D3, and calcium supplementation with your doctor. They can help you decide if it's right for you.

Focus on a Balanced Approach: This study suggests a combination of nutrients may be beneficial. A healthy diet, exercise, and other lifestyle choices are also important for strong bones.

Study Limitations

Specific Group: The study only looked at older women in Scotland, so the results might not apply to everyone.

Limited Scope: The study focused on the wrist, not other important bones like the hip.

Dosage: The amount of vitamin D3 used was lower than what is often recommended.

More Research Needed: More studies are needed to confirm these findings and see if they apply to a wider group of people.

Key Findings

This 2-year randomized controlled trial found that combined supplementation with vitamin K1 (200 µg/day), vitamin D3 (10 µg/day), and calcium (1000 mg/day) modestly increased bone mineral content (BMC) and bone mineral density (BMD) at the ultradistal radius (trabecular bone site) in healthy, nonosteoporotic women aged ≥60 years. No significant effects were observed at the hip or mid-distal radius. Vitamin K1 supplementation alone improved gamma-carboxylation of osteocalcin (a marker of bone health), reducing undercarboxylated osteocalcin (%GluOC) by 51% (p < 0.001). The combination group also saw a 157% increase in serum vitamin K1 (p < 0.001) and a 17% rise in 25-hydroxyvitamin D [25(OH)D] (p < 0.001), alongside a 11% decrease in parathyroid hormone (PTH) (p = 0.049).

Study Design

A double-blind, placebo-controlled RCT with 244 healthy Scottish women aged ≥60 years. Participants were randomized into four groups: (1) placebo, (2) vitamin K1 alone, (3) vitamin D3 + calcium, and (4) combined K1 + D3 + calcium. Bone health was assessed via DXA scans (hip, wrist) and blood biomarkers at baseline and 6-month intervals. Analysis adjusted for baseline variables and confounders.

Dosage & Administration

Vitamin K1: 200 µg/day (phylloquinone).
Vitamin D3: 10 µg/day (400 IU) + calcium: 1000 mg/day.
Supplements were administered daily, though specific formulation (e.g., capsules, tablets) and timing (e.g., with meals) were not detailed.

Results & Efficacy

BMC/BMD: Only the ultradistal radius showed significant improvements in the combination group (p < 0.05 vs. placebo). No effects at hip or mid-distal radius.
Bone turnover markers:
%GluOC decreased by 51% with K1 (p < 0.001), indicating enhanced osteocalcin carboxylation.
PTH reduced by 11% in the combination group (p = 0.049).
Serum levels:
Vitamin K1 increased by 157% (p < 0.001).
25(OH)D rose by 17% in the D3 + calcium groups (p < 0.001).

Limitations

Population specificity: Only healthy, nonosteoporotic older women in Scotland were studied; results may not generalize to men, younger individuals, or populations with vitamin deficiencies.
Vitamin D dosage: 400 IU/day of D3 is below current recommended levels (600–800 IU/day), potentially limiting synergy detection.
Site-specific effects: Benefits were confined to the ultradistal radius, leaving other critical sites (e.g., hip) unaffected.
Short duration: 2 years may be insufficient to evaluate long-term fracture risk or cortical bone outcomes.
Dietary vs. supplemental K1: Authors speculated that dietary K1 could achieve similar gamma-carboxylation benefits, but this was not directly tested.

Clinical Relevance

For older women, combining vitamin K1 with moderate D3 and calcium may support trabecular bone health at the wrist, though effects are modest. The reduction in %GluOC suggests vitamin K1 improves osteocalcin function, which could theoretically enhance bone quality over time. However, the lack of hip or spine benefits and the low D3 dose limit broader recommendations. Clinicians might prioritize dietary sources of K1 (e.g., leafy greens) over supplementation, given the study’s suggestion that nutritional intake could suffice for gamma-carboxylation. Further research is needed to confirm synergy with higher D3 doses and diverse populations.

Vitamin K1, D3 & Calcium for Stronger Bones?