Vitamin D3 (also known as cholecalciferol) and vitamin K2 (also known as menaquinone) are two important nutrients that work synergistically to support bone and heart health. Determining the optimal dosage of vitamin D3 and K2 to take on a daily basis involves considering several factors such as age, health status, sun exposure, and more. Research suggests that vitamin D3 intake should be in the range of 1000-4000 IU per day for most adults, while the recommended intake of vitamin K2 is generally around 100-200 mcg per day.
Benefits of Vitamin D3 and K2
Vitamin D3 is essential for promoting calcium absorption and maintaining adequate serum calcium and phosphate levels to support bone health and prevent conditions like osteoporosis and osteomalacia. Vitamin K2 works synergistically with vitamin D3 by activating proteins that incorporate calcium into bones and teeth. Vitamin K2 also prevents calcium from depositing into soft tissues like blood vessels, reducing risk of arterial calcification and cardiovascular disease. Together, vitamins D3 and K2 provide a host of benefits:
- Build strong, dense bones and teeth
- Prevent fractures and brittle bones
- Reduce risk of osteoporosis
- Support immune function
- Reduce inflammation
- Support heart health by preventing arterial calcification
- Reduce risk of cardiovascular disease
- Potentially protect against cancer, diabetes, cognitive decline, autoimmune disease, and more
Factors that Determine Dosage Needs
There are several important factors that impact an individual’s dosage needs for vitamins D3 and K2:
1. Age
Older adults tend to require higher intakes of vitamin D3 to maintain optimal blood levels compared to younger people due to less efficient synthesis of vitamin D in the skin and reduced intestinal absorption. Infants require 400-1000 IU vitamin D3 per day while adults over 50 may need around 5000 IU per day or more. Vitamin K2 needs also tend to increase with age.
2. Sun Exposure
Vitamin D3 is synthesized in the skin when exposed to UVB sunlight. People who get regular sun exposure may have less need for supplemental vitamin D3 compared to those who spend a lot of time indoors. However, it’s important not to get excessive sun exposure due to skin cancer risk.
3. Skin Tone
Individuals with darker skin tones have more melanin in their skin, which reduces vitamin D3 production from sunlight. Those with darker complexions may therefore need more supplemental vitamin D3.
4. Geographic Location
People living farther from the equator synthesize less vitamin D3 year-round due to the sun’s rays hitting the earth at an oblique angle during the winter months. Some public health authorities even recommend everyone living above latitudes of around 35 degrees north or south take vitamin D supplements.
5. Overweight/Obesity
Excess body fat binds and sequesters vitamin D3 so overweight and obese individuals may need 2-3 times more vitamin D3 intake to maintain sufficient blood levels compared to those with leaner body compositions.
6. Malabsorption Disorders
Gastrointestinal disorders that impair fat absorption like celiac disease, Crohn’s disease, cystic fibrosis, and post-bariatric surgery status can increase vitamin D3 requirements. Strict vegetarian and vegan diets may also interfere with vitamin D3 absorption.
7. Liver/Kidney Disease
Individuals with compromised liver and kidney function are less able to convert vitamin D3 into its active form. They may need higher intakes to account for this reduced conversion efficiency.
8. Certain Medications
Some medications like anticonvulsants, glucocorticoids, antifungals, and HIV/AIDS medications can affect vitamin D3 metabolism and increase supplementation needs.
9. Laboratory Testing
Measuring 25-hydroxy vitamin D blood levels provides a precise way to evaluate your individual vitamin D3 status and tailor your dosage needs accordingly. Optimal 25(OH)D levels are generally considered to be between 30-80 ng/mL.
General Vitamin D3 Recommendations
While vitamin D3 needs can vary significantly based on the factors described above, the table below provides general intake recommendations from major health authorities:
| Age | Recommended Vitamin D3 Intake |
|---|---|
| 0 – 12 months (infants) | 400 – 1000 IU per day |
| 1 – 18 years (children/adolescents) | 600 – 1000 IU per day |
| 18+ years (adults) | 600 – 8000 IU per day |
| Pregnant/lactating women | 600 – 2000 IU per day |
| Adults 50+ years | 800 – 2000 IU per day |
As shown above, the Endocrine Society recommends adults take 1500-2000 IU of vitamin D per day to maintain optimal serum 25(OH)D levels above 30 ng/mL. Other expert groups like the Vitamin D Council recommend higher intakes in the range of 5000 IU/day for adults.
General Vitamin K2 Recommendations
The adequate intake (AI) level for vitamin K2 set by the Food and Nutrition Board is around 120 mcg daily for adult women and 90 mcg daily for adult men. However, many functional medicine practitioners recommend higher daily vitamin K2 intakes between 150-180 mcg. For therapeutic use in conditions like osteoporosis, dosages up to 200 mcg per day may be appropriate under medical supervision.
The best food sources of vitamin K2 include:
- Natto: 133 mcg per 100 grams
- Goose liver pate: 100 mcg per 100 grams
- Hard cheeses like gouda: 76 mcg per 100 grams
- Soft cheeses like brie: 57 mcg per 100 grams
- Egg yolk: 32 mcg per yolk
- Butter: 15 mcg per tablespoon
- Chicken liver: 14 mcg per 100 grams
- Salmon: 11 mcg per 100 grams
However, consistently meeting the body’s vitamin K2 needs from foods alone can be challenging for many people. Supplementing with a bioavailable form like menaquinone-7 may be highly beneficial.
Finding the Optimal Vitamin D3 and K2 Balance
Evidence suggests an optimal ratio for vitamins D3 and K2 is around 100:1 to 150:1 (measured in micrograms). This means for every 1000-5000 IU of supplemental vitamin D3 you take per day, adding 100-150 mcg of vitamin K2 can help balance these two nutrients.
Combining D3 and K2 together in one capsule/tablet is an efficient way to ensure proper ratios are maintained. Many supplements provide 1000-2000 IU of D3 with 80-100 mcg of K2 for instance. Measuring blood levels of vitamin D and consulting with a knowledgeable healthcare practitioner can help determine the ideal ratio and dosages of vitamin D3 and K2 for your individual needs.
Safety and Tolerability
Both vitamin D3 and K2 supplements are extremely well tolerated by most people, even at higher dosages. However, some key safety precautions include:
- Vitamin D toxicity is possible but very rare if intake climbs above 50,000 IU daily for prolonged periods. Mild hypercalcemia can occur above 10,000 IU per day in sensitive individuals.
- Vitamin K2 has very low toxicity potential, but those on blood thinners should consult their doctor before supplementing.
- Seek medical advice before supplementing if you have a history of kidney stones, high blood calcium, sarcoidosis, tuberculosis, or other health conditions.
- Divide dosages into morning and evening to enhance absorption and minimize spikes in blood levels.
- Purchase high quality supplements standardized for maximum purity and potency.
The Bottom Line
Most healthy adults should aim to get 1000-4000 IU of supplemental vitamin D3 per day from a combination of sun, food, and supplements. Adding 100-200 mcg of vitamin K2 helps direct calcium into bones and prevents vascular calcification.
Monitoring blood levels of vitamin D and adjusting intake accordingly is the most precise way to meet individual needs. Those with identified deficiencies may require short-term loading doses of 5000-10,000 IU vitamin D3 under medical guidance to restore optimal status.
Supplementing with bioavailable forms of vitamins D3 and K2 together provides synergistic benefits for bone and cardiovascular health. When taken as directed, these fat-soluble vitamins have very low toxicity potential yet offer a multitude of benefits for people of all ages.