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Vitamin K: The essential fat-soluble vitamin
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Vitamin K

Vitamin K is a nutrient that the body needs to stay healthy.

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Vitamin K is a fat-soluble vitamin that is naturally present in some foods.

Vitamin K, vitamin A, vitamin D, and vitamin E are all fat-soluble vitamins, which require fat to be circulated in and absorbed by our body.

Vitamin K is essential for healthy bones, blood clotting, and other bodily functions.

There are two main types of vitamin K, phylloquinone and a series of menaquinones. Phylloquinone is also called vitamin K1; the series of menaquinones are collectively called vitamin K2.

Vitamin K1 is primarily a plant-sourced vitamin K; Vitamin K1 is made by plants and is found in the highest amounts in green leafy vegetables like kale, collard greens, and spinach. Vitamin K1 is the main dietary form of Vitamin K.

Menaquinones (Vitamin K2) are mainly from animal-based foods and fermented foods. Almost all menaquinones, particularly the long-chain menaquinones. are also produced by bacteria in the human gut.

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More about Vitamin K2

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Vitamin K2 is composed of a series of menaquinones.

 

Menaquinones are abbreviated MK-n, where M stands for menaquinone, K stands for vitamin K, and n represents the number of unsaturated isoprenyl side chains. Menaquinones are designated as MK-4 through MK-13 based on the number of n, which denotes the length of their side chain. For example, menaquinone-4, abbreviated as MK-4, has four isoprenyl side chains. MK-4, MK-7, and MK-9 are the most well-studied menaquinones.

 

Vitamin K2 is usually found in animal products and fermented foods. The most common menaquinone in the human diet is short-chain, water-soluble menatetrenone, which is MK-4. MK-4 is a unique menaquinone in that it is produced by the body from vitamin K1 via a conversion process that does not involve bacterial action.

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What does Vitamin K do in our bodies?

The function of vitamin K includes the following three aspects:

  • Vitamin K stops bleeding and avoids excessive bleeding. This is because the human body requires vitamin K to make the proteins needed for blood coagulation.

  • Vitamin K regulates calcium metabolism; Vitamin K is vital for healthy bones, and Vitamin K helps maintain bone strength and prevent osteoporosis. Vitamin K plays a role in the binding of calcium in bones.

  • Vitamin K plays a crucial role in cellular signaling and new cell growth.

The Food Sources of VitaminK:

  • Food sources of vitamin K1 include vegetables, especially green leafy vegetables, vegetable oils, and some fruits (such as blueberries and grapes).

  • Meat, dairy foods, and eggs have modest amounts of menaquinones and low levels of Vitamin K1.

  • Natto is a traditional Japanese food made from fermented soybeans. Natto has high amounts of Vitamin K2.

  • The most common sources of Vitamin K in the North American diet are spinach, broccoli, kale, lettuce, fats and oils, mainly soybeans and canola oil.

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The top foods containing Vitamin K:

  • Natto

  • Collards

  • Turnip greens

  • Spinach

  • Kale

  • Broccoli

  • Soybeans and soybean oil

  • Carrot juice

  • Edamame

  • Pumpkin

  • Pomegranate juice

  • Okra

  • Pine nuts

  • Blueberries

  • Iceberg lettuce

  • Chicken breast

  • Grapes

  • Canola oil

  • Cashews

  • Carrots

  • Olive oil

Recommended Amounts:

The recommended amount of vitamin K is given in adequate intakes (AI) in micrograms (mcg) units. For teens 14 to 18 years old, the AI of vitamin K is 75 micrograms (mcg) daily. The AI for adult men 19 years and older is 120 micrograms (mcg) daily, and for adult women (19 years and older) is 90 micrograms (mcg) daily. For teen girls (14-18 years old) in pregnancy and lactation, the AI is 75 micrograms (mcg) daily; for women 19 years to 50 years old in pregnancy and lactation, the AI is 90 micrograms (mcg) daily.

 

What is AI (adequate Intake)?

Adequate Intake (AI) means Intake at this level is assumed to ensure nutritional adequacy, established when evidence is insufficient to develop an RDA.

 

RDA is Recommended Dietary Allowance (RDA), which means the Average daily level of Intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals; often used to plan nutritionally adequate diets for individuals.

Recommended dietary allowances (RDAs) for vitamin D
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Vitamin K and Healthful Diets

Our nutritional needs should be met primarily through foods because foods provide an array of nutrients and other components that benefit health. Foods contain vitamins, minerals, dietary fibre, and other nutrients that are beneficial for our health. In some situations and cases, fortified foods and dietary supplements are helpful when it is impossible to meet the needs for one or more nutrients.

A healthy dietary pattern was described by “The Dietary Guidelines for Americans” as one that:

Includes a variety of vegetables; fruits; grains, and whole grains; milk, yogurt, cheese; and oils. Food sources of vitamin K include vegetables, especially green leafy vegetables, vegetable oils, and some fruits (such as blueberries and grapes).

  • Includes a variety of protein foods, for example, lean meats; poultry; eggs; seafood; beans, peas, lentils; nuts and seeds; and soy products. Soybeans and nuts contain vitamin K.

  • Limits foods and beverages higher in sodium, added sugar, and saturated fat.

  • Limits alcoholic beverages.

  • Stays within your daily calorie needs.

References:

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