The Importance of Vitamin K – The Use of Supplementation During Winter
Author: Dr. Jimi Francis, PhD, IBCLC, RDN, LD, RLC
As the days grow shorter and winter sets in, many people focus on vitamin D supplementation to compensate for reduced sunlight exposure. However, vitamin K, a lesser-known but equally important nutrient, deserves some attention, too—especially when considering bone health, cardiovascular function, and overall well-being.
What is Vitamin K?
Vitamin K is a fat-soluble vitamin essential for several bodily functions, primarily blood clotting and bone metabolism. It comes in two primary forms:
Vitamin K1 (phylloquinone): Found in green leafy vegetables such as spinach, kale, and broccoli. It plays a significant role in blood clotting.
Vitamin K2 (menaquinone): Found in fermented foods, animal products, and certain cheeses. K2 is created by certain bacteria in the human gut microbiome. Menaquinone is crucial for bone health and cardiovascular function, directing calcium to the bones and away from arteries.
Increasing evidence suggests that people who take high doses of vitamin D (often over 2,000 IU daily) should also supplement with vitamin K2. Vitamin D increases calcium absorption; without adequate vitamin K2, the calcium may deposit in arteries instead of bones, posing potential risks to cardiovascular health. Some health practitioners suggest taking up to 180-200 mcg of K2 daily with higher vitamin D intake. In contrast, others argue this dosage is excessive, pointing out that high levels of vitamin K2 supplementation have yet to be extensively studied for long-term safety.
Another controversy is the debate over the need for vitamin K2 specifically. While vitamin K1 (found in leafy greens) is recognized for its role in coagulation, there needs to be more consensus on whether vitamin K2 (found in fermented foods and animal products) should be prioritized for supplementation. Some experts emphasize the unique benefits of K2 for bone and cardiovascular health. Still, others suggest that a well-rounded diet rich in vitamin K1 may suffice, as the body can convert some K1 to K2, empowering individuals to take control of their health through their dietary choices.
The Role of Vitamin K in Winter Months
Winter, with its reduced availability of fresh, vitamin K-rich foods like leafy greens, can be challenging for maintaining adequate vitamin K levels. Also,
colder weather may lead to a more sedentary lifestyle, which can impact bone health. This makes ensuring adequate vitamin K levels, especially for those supplementing vitamin D, even more critical.
Vitamin K and vitamin D work together synergistically. While vitamin D promotes calcium absorption, vitamin K ensures that the calcium is deposited in the right places, such as bones and teeth, rather than in arteries or soft tissues, where it could contribute to calcification and other health problems.
Why Consider Supplementation?
During the winter months, there are several reasons why vitamin K supplementation may be important: …
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