The Different Forms of Vitamins D and K, Which Is Right for You?

Vitamin D2 vs. D3 What's the Difference?

Vitamin D, an essential nutrient for a healthy immune system, teeth, and bones is naturally synthesized in skin and then converted by the body to its active form. Otherwise it can also be obtained from both plant and animal foods, a necessity when there is insufficient exposure to sunshine to produce the Vitamin D in the quanitity the body requires for good function.

The Vitamin D3 found in animal sources is called cholecalcaiferol. The plant form, Vitamin D2 is called ergocalciferol. The liver processes these two forms of vitamin D differently, and D3 is generally more effective at raising levels of Vitamin D in the body and sustaining them longer than D2. ( https://doi.org/10.1111/nbu.12293)

Mushrooms exposed to sunlight are the primary plant source of Vitamin D2, which can also be found in a fungus in lichen, and alfalfa shoots. Mushrooms and fungus grown in dark places can be exposed to UV light to increase the amount of Vitamin D in them. Processed foods may be fortified with a synthetic Vitamin D2, such as "fortified" milk and cereals.

Vitamin D3 is formed in the oils on human skin, or it can be best obtained from food sources like cold water oily fish, beef liver, egg yolks, some cheeses. Fats from pasture-raised animals are richer in natural Vitamin D3 than from animals not exposed to the sun or not allowed fresh green plants to eat.

Many D3 supplements that are not made from whole food sources, are made by extracting the lanolin (oil) in sheep's wool, and exposing it to ultra-violet light. This process is similar to the way sunlight produces Vitamin D in the oils on human skin.

Still, with whatever form you choose, consistency is key. If you are are going outside in the midday sun for UVB rays, do it several times each week to get enough sun to allow your body to make the Vitamin D it needs. It can difficult to obtain enough Vitamin D from sun exposure alone because of our indoor living habits. The sun should be overhead at 50 degrees or higher to get enough UVB rays to make Vitamin D3. This is not the case at every latitude and season. Most of us need to supplement in order prevent deficiency in this essential vitamin.

Vitamin K1 vs. K2, do I need both?

All forms of Vitamin K share a similarity in chemical structure, but K1 and K2 are the two forms we consume the most in our diet.

Vitamin K1 or phylloquinone is found in plants, particularly leafy green vegetables like spinach, kale, and collard greens.

Vitamin K2 is found mostly in animal products, in some fermented foods and cheeses, or is produced by gut bacteria. This form of Vitamin K has many subtypes called menaquinones (MKs) ranging from MK-4 to MK-13.

Vitamin K2 may be better absorbed by the body than K1 and circulates in the blood much longer. Because of this longer circulation time, Vitamin K2 can be better utilized by more tissues in the body than Vitamin K1 which is used primarily by the liver (https://pubmed.ncbi.nlm.nih.gov/8813897/)

Vitamin K1 and K2 serve different roles in the body. While K1 is mainly involved in blood coagulation (clotting), K2 is essential to transport calcium to bones and teeth and away from soft tissues. K2 is known to improve bone density and dental health, but also notas many people know that it supports cardiovascular health and immune and cognitive funcions. With Vitamin D, it is responsible for producing K-dependent proteins that work throughout the body.

While the body partly converts K1 into K2, you may find more health benefits by eating foods high in K2 or using a supplement.

Foods rich in Vitamin K2 are dairy products, especially hard aged cheeses, liver and organ meat, egg yolks, beef, pork, chicken, and certain fermented foods. Vitamin K is fat solubleyou can absorb them from high quality animal fats, or eat your greens with some good fats like avocados, olive oil or coconut oil.

Vitamin D and K for Vegans and Vegetarians

While many Vitamin D and K supplements come from animal sources, there are plenty of plant-based options to choose from too!

Plants are the primary source of Vitamin D2 and can be easy to obtain on a vegan or vegetarian diet.

Vitamin D3, which can be more readily absorbed by the body and may stay in the bloodstream longer than Vitamin D2 is found mostly in animal products. While following a plant based diet, this form of Vitamin D may be best obtained through supplementation.

Vitamin D supplements made from Lichen, small aquatic plants similar to algae that have been exposed to UV rays offer a rich source of Vitamin D3 for vegans and vegetarians.

Mushrooms can be a good source of this form of Vitamin D as well.

Plants, particularly leafy greens are also a rich source of Vitamin K1, another good reason to eat your greens!

This form of Vitamin K is essential for blood coagulation, while K2 works in tandem with Vitamin D to deliver calcium to bones and teeth and away from soft tissues. K2 can improve bone density and dental health and supports cardiovascular health too.

Vitamin K2 can be obtained from plant based supplements made from fermented soybeans or chickpeas.

The Japanese dish Natto, made from fermented soybeans offers a potent plant-based dose of D3. Other rich sources of Vitamin K2 for vegans and vegetarians are fermented foods like saurkraut, kimchi, and unpastuerized kombucha.