Vitamin K: Why You Need This Now

Think back to the last time you were bleeding–papercuts, scraped knees, sliced fingers from overzealous meal prepping. Do you remember how long it took for the wound to stop bleeding? Maybe it was small enough to finish within a minute. Or maybe you covered it with a bandage and didn’t check until hours after it stopped. Either way, unless you have a specific medical condition, the wound stopped bleeding thanks to blood clotting (or coagulation).

Without coagulation, you would still be bleeding now. There’s an agent behind the plug that you need to thank for saving you rolls of expensive gauze and new carpeting. An agent that you can find in your diet but may not be getting enough of.

Meet vitamin K, the essential dietary vitamin that stops you from bleeding out and much, much more.

Vital Signs: Vitamin Basics

Everyone knows what vitamins are. But if someone were to ask you to define a vitamin, what would you say? Simple question, complex concept. Unless you’re a dietitian or other medical professional, you may struggle to give a confident answer. And with the endless discordant sound bites about vitamin deficiencies, vitamin supplements, and vitamin-rich foods we should (or shouldn’t) be eating, it makes this question even more challenging to answer.

What’s a Vitamin?

Even though James Lind¹ first discovered lemon juice could treat scurvy in sailors in the mid-eighteenth century, it would be nearly a hundred years before anyone would know why it worked. It was merely a happy accident that he tested vitamin C-rich citrus fruits to those with a vitamin C deficiency. His less successful remedies? Half a pint of seawater daily, a pungent paste made of horseradish and garlic taken thrice daily, and six spoonfuls of vinegar throughout the day.

In the nineteenth century, physiologists identified four nutrient sources from our foods. In addition to the classic macronutrient trio of carbohydrates, proteins, and fats, they identified water as a comparable component of the diet. But it wasn’t until more research was being done into nutritional deficiencies that cause diseases, such as beriberi and rickets, that the physiologists came to identify the major micronutrients we also require.²

In 1913, Polish biochemist Casimir Funk observed that the hulk of unprocessed rice contained something to protect chickens from beriberi. He published his findings regarding the discovery of this “vital amine” with the proposed term “vitamine” to describe essential accessory factors of our diets. It wasn’t until 1926 that this “vitamine” was able to be isolated, named “thiamine,” and renamed vitamin B1 a decade later.²

Fast Facts: Vitamin Edition

In essence, a vitamin is an organic compound (meaning it contains carbon) that is separate from the macronutrients: fats, proteins, and carbohydrates. However, the current definition of a vitamin has several parameters. In addition to being an organic compound, a vitamin is a natural component of foods.

Vitamins are generally present in our foods in very small amounts. These small amounts are essential for our normal physiological function, such as growth and development.

When a vitamin is underutilized or completely absent, it can cause a specific deficiency syndrome. Conversely, vitamins prevent these deficiencies. Lastly, vitamins are not synthesized by their hosts in adequate amounts to meet normal physiological needs, hence the need to obtain them from our foods.²

Vitamin Properties

Vitamins belong to two categories: fat-soluble or water-soluble. The fat-soluble vitamins are those stored in the fatty tissues and the liver. They are much easier for the body to store than water-soluble vitamins, so they’re able to hang out in reserves anywhere from a few days up to a few months. We absorb fat-soluble vitamins through the intestinal tract with the help of fats themselves. The fat-soluble vitamins include A, D, E, and our vitamin VIP, K.

Water-soluble vitamins leave the body pretty quickly. Because we cannot store them the same way we can store our fat-soluble vitamins, they pass through the liquids in our bodies. In other words, we pee them out, so we’ll need to replenish them more often than the fat-soluble vitamins. If you check the missing letters from our fat-soluble alphabet, you’ll figure out that vitamins B and C are water-soluble.

Vitamins vs. Minerals

Now that we’re on the same page with what qualities constitute a vitamin, we can talk about all the different vitamins. One problem we may run into is the inadvertent inclusion of a completely different class of nutrients that are often lumped together with vitamins: minerals.

You’ve no doubt heard it before: “vitamins and minerals.” They’re often inseparable in discussions. But when it comes to nutrition, they couldn’t be more distinct. Recall that vitamins are organic compounds. Minerals? Inorganic substances. Vitamins are obtained through plants or animals synthesizing them. For instance, humans can make vitamin A from the beta-carotene we get when we eat carrots.

Minerals are easier to come by; you can literally find them under a rock. Or in one, rather, in addition to the soil beneath it. The delicate nature of vitamins makes them sensitive to destruction through certain cooking techniques. Minerals on the other hand are completely unfazed by not only high heat but also chemical reactions.

While both vitamins and minerals are required for proper body function, you don’t need all minerals the same way you need all vitamins. Remember that if a vitamin is absent or unsatisfactory, you will suffer from a deficiency disease (scurvy, anyone?). You don’t need to consume every mineral to maintain healthy functioning. There are 16 essential minerals listed below. Try to think of as many as possible before you read them.

• Calcium
• Iron
• Phosphorous
• Potassium
• Sulfur
• Copper
• Manganese
• Magnesium
• Sodium
• Fluoride
• Molybdenum
• Chromium
• Iodine
• Chloride
• Zinc
• Selenium

Vitamin Rundown

There are 14 essential vitamins our bodies need, each with its own sources, functions, and deficiency symptoms when lacking.

• Vitamin A
• Vitamins B1-3, 5-9, 12
• Vitamin C
• Vitamin D
• Vitamin E
• Vitamin K

Vitamin K may last, but it is certainly not least.

Vitamin K Essentials

Now that we have a better understanding of what vitamins are and how they work, we can zoom in on our celebrity compound, vitamin K.

Vitamin K was discovered after Danish scientist, Henrik Dam, went searching for the cause of hemorrhaging in chicks being fed low-fat diets in 1929. Several trials and one misdiagnosis of scurvy later, he found that a new fat-soluble factor present in plant and animal tissues was the missing vitamin needed to coagulate the blood. He fittingly (perhaps even unimaginatively) named this new discovery “Koagulations vitamin,” hence the K.³

Vitamin K can be broken down into two different types with very long and pronunciation-flexible titles: Phylloquinone and menaquinone. But if you’re not trying to impress a scientist, you can just refer to them as vitamin K1 and K2, respectively.

Vitamin K may not ring a bell the way other vitamins do. You could no doubt name rich sources of vitamin E, vitamin D, and vitamin A, and if you’re an overachiever, you could probably explain why we need them. But vitamin K gets overshadowed, and with its list of benefits, it’s hard to imagine why.

Vitamin K: Endless Cycle

Process this process: you have your very own vitamin K cycle taking place in your body right now.

In this metabolic process, your vitamin K undergoes some chemical changes, which facilitate the functions of certain proteins. Vitamin K is a cofactor for the enzymes contributing carboxyglutamic acid to proteins until they become a special class called Gla proteins.

Even if these proteins don’t sound familiar, your body knows them well—they’re involved in both blood clotting and bone metabolism, which we’ll discuss more in detail later.

For now, read on for where to find K1 and K2, what supplementing with the vitamin can do for our bodies, and what the future of the vitamin holds for our cognitive performance.

Where to Get Vitamin K

Thanks to Henrik, you won’t have to suffer low-fat diets and hemorrhaging to figure out what food sources contain vitamin K.

Phylloquinone (K1) is the type of vitamin K you’ve been told to eat your entire life. It’s one of many vitamins and minerals packed into the bundles of joy you visit in the produce aisle every week:

• Dark leafy greens: kale, mustard greens, spinach
• Green vegetables: broccoli, cabbage, Brussels sprouts
• Fruits: prunes, kiwi, avocado, blackberries
• Nuts and legumes: walnuts, chickpeas, pistachios, raw sugar peas, kidney beans

K1 is a fat-soluble vitamin, which as we discussed earlier, means it dissolves in fats and should be paired with fatty foods to be properly absorbed. It also means you have an excuse not to skimp on the oil-based dressing or extra sprinkle of nuts.

Menaquinone (K2) is the type of vitamin K you’ve been told to regulate—or even eliminate. That’s because K2 is a bacteria-based vitamin only present in fermented foods and fatty animal products, such as egg yolks and cheese.⁴ Here’s your excuse to let the waiter continue grating parmesan on top of your pasta.

Preserving Vitamin K Content

Earlier, we discussed the delicate nature of vitamins, which means excessive heat can damage them. Food preparations such as roasting, steaming, and microwaving can all affect the nutrient profile of your food.⁵ Each method has its merits and shortcomings.

Take vitamin K-rich broccoli, for example. Most of us aren’t interested in eating it raw. For good reason: even a simple steaming of this cruciferous veggie leads to an increase in its total amount of glucosinolates, which are sulfur-containing sugars with a powerful flavor,⁶ and even more powerful health benefits, such as assisting in the protection against cardiovascular disease and cancer progression.⁷

But if you choose to microwave broccoli instead, you may damage its vitamin C content.⁸ On the upside? Its vitamin K supply will remain largely intact, as vitamin K appears to stand up well to the pressure of cooking via gamma-irradiation.⁹

In greens such as spinach, broccoli, and lettuce, the bioavailability of phylloquinone (K1) appears to be roughly the same when eaten raw or cooked.

Supplementing with vitamin K1 in tandem with consuming the greens, however, appeared to increase the bioavailability of the nutrient.¹⁰

Vitamin K Deficiency

Whether food is cooked or raw, the problem is that many people don’t get the right amount of vitamin K through food alone. Children’s dietary vitamin K1 intake was significantly higher in 1950 than it is today because kids aren’t eating as many food sources containing phylloquinone.¹¹ Even American adults are consuming less vitamin K1and K2 than the dietary reference intakes set by the US Food and Drug Administration.¹²

These daily targets become even more difficult to hit with specialized diets, food allergies, and processed foods, which is why vitamin K supplementation is an efficient way to ensure you have an adequate intake of vitamin K1 and K2.

Serious vitamin K deficiency has some not-so-subtle symptoms associated with a lack of clotting factors: bruising easily, bleeding excessively, blood clotting underneath your fingernails, and very dark stool that contains blood.

To test for a vitamin K deficiency, a healthcare professional will usually perform a blood test measuring how long it takes for your blood to clot, otherwise known as the prothrombin test (PT). After taking a small blood sample with a needle, the professional will add chemicals to (hopefully) observe quick clotting. It usually takes about 11 to 13.5 seconds for the blood to clot. If you’re vitamin K deficient, yours will likely take longer.

Outside Influencers on Vitamin K

Let’s say you’re getting a proper amount of vitamin K through your diet alone. You could still be at risk of vitamin K deficiency if you have malabsorption syndrome.

Malabsorption syndrome is an umbrella term for numerous disorders in which the small intestine is unable to absorb adequate levels of nutrients and fluids.¹³ Often, it’s the micronutrients that go amiss: vitamins and minerals.

Unfortunately, there are several factors that can lead to malabsorption syndrome. Diseases such as celiac, Crohn’s, cystic fibrosis, and chronic pancreatitis are some common culprits. Others include long-term use of antibiotics, surgery or trauma-induced damage, congenital defects, radiation therapy, and the inability to produce certain digestive enzymes.¹³

If you’re a newborn, first of all, how are you reading this, and second of all, you have an even greater chance of developing a vitamin K deficiency. Newborn babies’ bodies are not set up for vitamin K success because they’re unable to produce any vitamin K2 on their own in their initial days of life, and even when they do, the liver doesn’t utilize the vitamin efficiently. Outside sources? Tough luck—vitamin K isn’t exactly known for its smooth transfer from the mother’s placenta. Even breast milk is no help. The solution is usually a small shot of vitamin K administered at birth.¹⁴

What Has Vitamin K Done for You Lately?

While obtaining your daily recommended intake of vitamin K is necessary for proper coagulation and staving off hemorrhagic disease, vitamin K is also important for bone and cardiovascular health, with particular benefits noted when taken in higher doses.

The key here is higher doses. You could always eat half a pound of Natto, the menaquinone-rich fermented soybean dish of Japan whose taste is lovingly described as bitter, pungent, and above all, acquired. But until you’ve acquired that taste, you’re welcome to vitamin K supplementation over obtaining it through food.