- September 1, 2017
- Sight and Life
- Most Recent, Nourish Notes
One often hears the term ‘it’s a matter of life and death’ but this is literally the case for Vitamin K! Vitamin K, also known as phylloquinone or menaquinone, has a vital role in blood clotting and thus also supports wound healing.
More than a dozen different proteins and the mineral calcium are involved in making a blood clot. Vitamin K is essential for the activation of several of these proteins. When any of the blood clotting factors is lacking, hemorrhagic disease (uncontrolled bleeding) results. Vitamin K also participates in the metabolism of bone proteins, most notably osteocalcin. Without vitamin K, osteocalcin cannot bind to the minerals that normally form bones, resulting in poor bone mineralization.
Storage and primary sources of vitamin K
Vitamin K is stored in the liver. Vitamin K is found in plant foods as phylloquinone (K1). Bacteria in the lower intestine can synthesize vitamin K as menaquinone (K2), which is absorbed by the body.
Sources of phylloquinone are green leafy vegetables (i.e., parsley, spinach, collard greens, and salad greens), cabbage, and vegetables oils (soybean, canola, olive). Menaquinones are also found in fermented foods such as fermented cheese, curds, and natto (fermented soybeans).
Bioavailability of vitamin K
Absorption of vitamin K from food sources is about 20%, and dietary fat enhances absorption.
Risks related to inadequate or excess intake of vitamin K
Deficiency of Vitamin K is rare as it is widely available from the diet and is also provided by gut bacteria. Thus, deficiency is generally secondary to conditions such as malabsorption or impaired gut synthesis. However, there is growing interest in the role of vitamin K in optimising bone health. Supplementation with vitamin K has been found to be beneficial for improving bone density among adults with osteoporosis because it drives synthesis of a special protein called matrix Gla protein.
Vitamin K is poorly transferred via the placenta and is not found in significant quantities in breast milk, so newborn infants are especially at risk for bleeding. This innate vitamin K deficiency is treated with intramuscular injection or oral administration of phylloquinone. Supplementation with vitamin K has been found to be beneficial for improving bone density among adults with osteoporosis because it drives synthesis of a special protein called matrix Gla protein.
Here is an easy way to incorporated vitamin K into your next meal.
Spinach, aubergine and chickpea curry*
1kg fresh spinach
2 tbsp olive oil
2 medium red onions, chopped
200g tinned chickpeas, drained and rinsed
2 garlic cloves, finely chopped
2 fresh hot green chillies, halved and thinly sliced, seeds included
1 tbsp coriander seeds, ground
1 tbsp cumin seeds
1 large aubergine, approx. 400g/14oz, cut into 2cm (3/4in) dice
400g tinned chopped tomatoes
Cook the spinach in boiling water for two minutes, then cool it under cold running water and squeeze gently to remove most of the liquid. Place in a food processor and chop the spinach to a coarse purée. Meanwhile, heat half the olive oil in a large pan and cook the onion, chickpeas, garlic, chilli and spices for five minutes over a medium heat. Next, add the remaining olive oil and the aubergine to the pan. Cook for ten minutes, stirring often, until the aubergine is colored. Then add the tomatoes and a pinch of salt. Cover the pan, lower the heat and simmer for 15 minutes until the aubergine is soft. Stir in the spinach purée and serve.
*Adapted from BBC Food Recipes