It’s common knowledge vitamin D is known as the sunshine vitamin because it's produced in the skin upon exposure to sunlight. Yet, vitamin D deficiency is common. Eighty percent of vitamin D is obtained through your skin from the sun (UVB exposure), but many individuals protect their skin from the sun. This can contribute to Vitamin D deficiency and related deficiency diseases. Aside from low skin-to-sun exposure, other factors of vitamin D deficiency include a poor diet low in oily fish and vitamin D-related gene polymorphisms. 

Aside from during the summer months, the skin makes little (if any) vitamin D from the sun at latitudes above 37 degrees North or below 37 degrees South of the equator. People living in these areas are at greater risk for vitamin D deficiency. 

Recent research suggests we need much more vitamin D than previously thought for optimal immune function and long-term health. 

What Does Vitamin D Do?

Cholecalciferol, also known as vitamin D3, is more biologically active in the body than vitamin D2.

• Vitamin D increases calcium absorption from the intestinal tract (bone health).
• Vitamin D reduces calcium losses in urine (bone health).
• Vitamin D mobilizes calcium from bone to maintain normal blood calcium levels (bone health).
• Vitamin D helps to moderate the inflammatory response and tissue damage during an immune response.
• Vitamin D deficiency is associated with immune function, cardiovascular health, mood and brain health, inflammatory bowel disease, bone health, and hormone balance.
• Along with vitamin A and thyroid hormone, vitamin D regulates the DNA of some cells to favor maturation into specific cell types. This is important in orchestrating tissue development in the fetus and growing child.

What Does Vitamin K Do?

• Vitamin K supports healthy blood flow and blood vessel health.
• Vitamin K works with Vitamin D when it comes to cardiovascular health and bone health (calcium regulation).
• Vitamin K supports a healthy immune response.
• Vitamin K helps to alleviate any potential increase in long-term side effects such as calcification in arteries and weak bones, by helping certain proteins bind to calcium.
• Vitamin K activates matrix GLa protein (MGP) which promotes lung and blood vessels health.  

How Does Vitamin K Benefit Vitamin D?

Studies now show Vitamin K greatly enhances the benefits of vitamin D, in terms of bone strength, lung health, and cardiovascular health. Vitamin D supports bone health by helping with calcium absorption. However, it is vitamin K that directs calcium to your skeleton, to prevent it from being deposited in the wrong areas.

Several different forms of vitamin K exist, with the primary form being vitamin K1, or phylloquinone, found primarily in green vegetables. Another form of vitamin K, known as vitamin K2 or menaquinone, is found primarily in animal products such as meat or eggs, as well as cheese and natto, a fermented soy product. While most of the benefits of vitamin K were previously attributed to vitamin K1, recent research has identified important benefits for vitamin K2.

How Much D3 + K2 Do You Need?

Scientists don't yet know the optimal daily dose of vitamin D, and recommendations vary depending on who you ask. Here are recs for adults from three different entities.

The Vitamin D Council recommends 5,000 IU/day

The Food and Nutrition Board recommends 600-800 IU/day

The Endocrine Society recommends 1,500-2,000 IU/day

One thing to know is it takes a lot of vitamin D to develop a toxicity—40,000 IU per day for a couple of months or longer, or a very large one-time dose. The best way to know if you’re deficient is to have your qualified healthcare professional test your serum levels of 25-hydroxy vitamin D. They will be able to recommend the best way for you to raise your vitamin D levels based on your lab results.

Regarding vitamin K2, studies show an amount of 180 to 200 micrograms should be enough to activate your body's K2-dependent proteins to shuttle the calcium where it needs to be and remove it from the places where it shouldn't.

Consider a combo vitamin D3 + K2 supplement to ensure your body's getting enough of what it needs.

In Health and Happiness,

Kelly Harrington, MS, RDN

Registered Dietitian Nutritionist for Healthy Goods