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What is vitamin K?

Vitamin K plays a key role in our blood’s ability to form clots. It’s one of the less glamorous vitamins, more rarely discussed than its peers and, although it’s usually referred to as a single substance, it comes in two natural varieties — K1 and K2 — and one synthetic one, K3. People typically cover their requirements of vitamin K through diet, so it’s rarely seen in supplement form, but we’ll also look at some situations that might require an extra input of vitamin K.

A molecule of menatetrenone, one of the forms of vitamin K2. Image via Wikimedia.

The ‘K’ in vitamin K stands for Koagulations-vitamin, Danish for ‘coagulation vitamin’. This is a pretty big hint as to what these vitamers — the term used to denote the various chemically-related forms of a vitamin — help our bodies do. Vitamin K is involved in modification processes that proteins undergo after they have been synthesized, and these proteins then go on to perform clotting wherever it is needed in our blood. Apart from this, vitamin K is also involved in calcium-binding processes for tissues throughout our bodies, for example in bones.

Although we don’t need very high amounts of vitamin K to be healthy (relative to other vitamins), a deficiency of it is in no way a pretty sight. Without enough vitamin K, blood clotting is severely impaired, and uncontrollable bleeding starts occurring throughout our whole bodies. Some research suggests that a deficiency of this vitamin can also cause bones to weaken, leading to osteoporosis, or to the calcification of soft tissues.

What is vitamin K?

Chemically speaking, vitamin K1 is known as phytomenadione or phylloquinone, while K2 is known as menaquinone. They’re quite similar from a structural point of view, being made up of two aromatic rings (rings of carbon atoms) with a long chain of carbon atoms tied to one side. K2 has two subtypes, one of which is longer than the other, but they perform the same role in our bodies. The K1 variety is the most often seen one in supplements.

Vitamin K3 is known as menadione. It used to be prescribed as a treatment for vitamin K deficiency, but it was later discovered that it interfered with the function of glutathione, an important antioxidant and key metabolic molecule. As such, it is no longer in use for this role in humans.

They are fat-soluble substances that tend to degrade rapidly when exposed to sunlight. It also breaks down very quickly and is excreted quickly in the body, so it’s exceedingly rare for it to reach toxic concentrations in humans. Vitamin K is concentrated in the liver, brain, heart, pancreas, and bones.


Vitamin K is abundant in green, leafy vegetables, where it is involved in photosynthesis. Image credits Local Food Initiative / Flickr.

As previously mentioned, people tend to get enough vitamin K from a regular diet.

Plants are a key synthesizer of vitamin K1, especially their tissues which are directly involved in photosynthesis; as such, mixing leafy or green vegetables into your diet is a good way to access high levels of the vitamin. Spinach, asparagus, broccoli, or legumes such as soybeans are all good sources. Strawberries also contain this vitamin, to a somewhat lesser extent.

Animals also rely on this vitamin for the same processes human bodies do, so animal products can also be a good source of it. Animals tend to convert the vitamin K1 they get from eating plants into one of the varieties K2 (MK-4). Eggs or organ meats such as liver, heart, or brain are high in K2.

All other forms of K2 vitamin are produced by bacteria who produce it during anaerobic respiration. As such, fermented foods can also be a good source of this vitamin.

Some of the most common signs of deficiency include:

  • Slow rates of blood clotting;
  • Long prothrombin times (prothrombin is a key clotting factor measured by doctors);
  • Spontaneous or random bleeding;
  • Hemorrhaging;
  • Osteoporosis (loss of bone mass) or osteopenia (loss of bone mineral density).

Do I need vitamin K supplements?

Cases of deficiency are rare. However, certain factors can promote such deficiencies. Most commonly, this involves medication that blocks vitamin K metabolism as a side-effect (some antibiotics do this) or medical conditions that prevent the proper absorption of nutrients from food. Some newborns can also experience vitamin K deficiencies as this compound doesn’t cross through the placenta from the mother, and breast milk only contains low levels of it. Due to this, infants are often given vitamin K supplements.

Although it is rare to see toxicity caused by vitamin K overdoses, it is still advised that supplements only be taken when prescribed by a doctor. Symptoms indicative of vitamin K toxicity are jaundice, hyperbilirubinemia, hemolytic anemia, and kernicterus in infants.

Vitamin K deficiencies are virtually always caused by malnourishment, poor diets, or by the action of certain drugs that impact the uptake of vitamin K or its role in the body. People who use antacids, blood thinners, antibiotics, aspirin, and drugs for cancer, seizures, or high cholesterol are sometimes prescribed supplements — again, by a trained physician.

How was it discovered?

The compound was first identified by Danish biochemist Henrik Dam in the early 1930s. Dam was studying another topic entirely: cholesterol metabolism in chickens. However, he observed that chicks fed with a diet low in fat and with no sterols had a high chance of developing subcutaneous and intramuscular hemorrhages (strong bleeding under the skin and within their muscles).

Further studies with different types of food led to the identification of the vitamin, which Dam referred to as the “Koagulations-Vitamin”.

Some other things to know

Some of the bacteria in our gut help provide us with our necessary intake of vitamin K — they synthesize it for us. Because of this, antibiotic use can lead to a decrease in vitamin K levels in our blood, as they decimate the populations of bacteria in our intestines. If you’re experiencing poor appetite following a lengthy or particularly strong course of antibiotics, it could be due to such a deficiency. Contact your physician and tell them about your symptoms if you think you may need vitamin K supplements in this situation; it’s not always the case that you do, but it doesn’t hurt to ask.

Another step you can take to ensure you’re getting enough vitamin K is to combine foods that contain a lot of it with fats — as this vitamin is fat-soluble. A salad of leafy greens with olive oil and avocado is a very good way of providing your body with vitamin K and helping it absorb as much of it as possible.

The Science of Manufacturing Supplements

Nutritional come in all shapes and sizes. Some vitamins are pressed into pill form, taken as liquids, mixed into foods and even offered as injections. Herbal formulas are concentrated into extracts, turned into green juice powders, or blended into smoothies. Many of the foods you eat also have nutritional enrichments and fortifications; depending on the dietary choices you make, these can be important sources of micronutrients too. 

Vitamins and minerals, herbs, and targeted formulas are the three main classifications into which nutritional supplements fall. Although the categories overlap – most green superfood supplements tout their high vitamin and mineral content, for example – they differ in how they’re manufactured and administered.

The Making of a Vitamin Supplement

Supplements cover a wide range of nutritional needs, but not everything that is part of a supplement is a vitamin. Nutritionists term only 13 compounds vitamins. They include vitamins A, C, D, E and K as well as the numbered B-complex vitamins, folate, biotin, and pantothenate. B-complex vitamins and vitamin C are water-soluble, and the rest are fat-soluble. Manufacturers of multi-vitamins must take solubility and bio-availability into account when preparing pressed tablets or capsules. 

After ordering raw materials from distributors and checking certificates of analysis to ensure uniformly high quality, vitamin supplement manufacturers then blend ingredients according to a proprietary formula. Depending on whether the product is meant to be a pill, liquid or powder, the formula might also contain inert, food-grade binders and fillers to hold the finished product together or keep it flowing freely. Throughout the process, quality assurance personnel sample batches of the product and analyze it for the proper proportions of active ingredients. 

Natural vs. Synthetic Vitamins

Debates continue about the relative merits of naturally sourced vitamins and those synthesized in a lab. Proponents of natural and organic supplements say nature’s methods are always better, but research suggests the answer isn’t always so straightforward.

Some vitamins are identical whether they come from organic sources or are created from their constituent ingredients. Vitamin C, or ascorbic acid, has a relatively simple molecular structure that’s the same whether it comes from oranges and rose hips or is derived from glucose. Pure ascorbic acid, then, is equally effective whether it has a natural or a synthetic source. 

Some synthetic vitamin supplements may be more effective for some people than others. Vitamin B9, otherwise known as folate, is essential to proper neural tube development. It’s also available as a precursor called folic acid. While the majority of people who take it can readily convert folic acid into folate, that may not be true of everyone. In Reviews in Obstetrics and Gynecology, Dr. James A. Greenberg recommends the more bio-available L-methylfolate supplements over folic acid for women who have a history of early births in their family. On the other hand, for those who do metabolize it efficiently, folic acid is roughly 85 percent bio-available compared to 50 percent bio-availability for naturally occurring folate, according to the National Institutes of Health’s Folate Fact Sheet

For at least one vitamin, peer-reviewed studies have shown that natural sources are currently better. In an article published in the International Journal for Vitamin and Nutrition Research, scientists found that synthetically created vitamin E was in a form that was safe but less effective than naturally ocurring vitamin E. The difference is a slight change to the molecular structure of the vitamin, making some of it pass through the body instead of being in a usable form. Naturally derived vitamin E was approximately 1.4 times as effective, dose for dose, as its synthetic counterpart. 

These guidelines hold true for the pure forms of vitamins, but supplements are usually mixed with fillers, binders or other active ingredients. Some market themselves as all natural while others blend synthetically derived and naturally sourced ingredients. Talking with your family physician or a licensed nutritionist will help you decide on which vitamin supplements are right for you. Before purchasing, you should also consider doing some online research into the marketing of the supplement you wish to purchase. There are many supplement websites, which provide you with the best market choices based on criteria such as ingredients, value and pricing, manufacturer claims, user feedback and more.

Forms of Vitamin Supplements

From convenient pills to easy-to-swallow liquids, your vitamin supplements are there for you in multiple forms to suit your needs. 

  • Pills: The most common form of vitamin supplement, pressed pills are designed with portability and ease in mind. Multi-vitamins most often come in pill form because it’s the easiest way to blend and administer ingredients. Solubility is an important consideration with vitamins in pill form, so look for the USP label on vitamins. This label means the pill has been tested and proven to dissolve in the stomach. 
  • Powders: Vitamins in powder form often come with additional supplements such as protein or herbs. Some people prefer powders to pills as they’re easier to sprinkle on food or mix into drinks, but they can be more of a challenge to portion properly.
  • Capsules: Made of soluble gelatin, capsules dissolve more rapidly than pressed pills. The fat-soluble vitamins, especially vitamin E, typically come in a liquid capsule form. These clear, soft capsules are easy to swallow or apply topically to your skin as an anti-aging treatment.
  • Gummy and Chewable Vitamins: A newer entry into the realm of vitamin supplements, gummy vitamins contain the same active ingredients as other formats, but they’re suspended in a tasty, chewy gelatin base instead of a pressed pill or powder. Gummy and chewable vitamins are especially popular with kids but keep them out of reach so children don’t eat them like candy. 
  • Liquids: In liquid form, vitamins are easy to take and digest quickly. They’re also simple to mix into foods and drinks. To make dosage easier, some manufacturers put out single-use ampoules of liquid vitamins, while others supply a calibrated dropper for accurate measurement.
Vitamins, Minerals and Safety 
When taken as directed by your physician, vitamins and multi-vitamin supplements with minerals are generally safe, but there are important precautions to keep in mind. Fat-soluble vitamins, including vitamins A, D, E and K, remain in your system longer and can build up in your body’s tissues. If you take blood thinners or certain other medications, talk to your doctor about possible interactions with vitamin E and vitamin K supplements, recommends the Food and Drug Administration (FDA). 

Herbal Supplements from Farm to Pharmacy

Vitamins are far from the only supplements you might find in your kitchen. Dietary supplements have become a multi-billion-dollar industry, and herbal formulas are a big part of that burgeoning business. While vitamins and minerals are more of a known quantity, the benefits of herbal preparations vary greatly based on what the formula contains, what it’s supposed to do, and how it’s taken. Another difference between vitamins and herbal supplements is that herbal formulas are typically targeted to address a particular health concern, while multi-vitamins are designed to promote overall health. 

Botanical sources for healing are as old as human history. Since ancient times, physicians have known about the ability of willow bark to bring down a fever or chamomile to calm. It wasn’t until recently that researchers began to discover the compounds in herbal remedies that made them effective. Willow bark, for example, contains a compound similar to aspirin. 

In some cases, powerful drugs have been derived from organic sources. Digoxin, a potent medication that helps regulate and strengthen heart rhythms, comes from digitalis, commonly known as foxglove. Because herbs can also have medicinal effects, it’s important to take these supplements as directed and inform your physician of everything you take to avoid interaction with other medications. 

Herbal remedies come in numerous forms, but the most popular include the following types: 

  • Herbal Pills and Capsules: Like vitamins, herbs can be milled into fine powders and pressed into tablets or enclosed in gelatin capsules. For herbal supplements that have a strong taste, pills and capsules can make remedies more palatable. Garlic supplements, for example, can have a marked taste that would affect a drink powder, but they’re easy to take in capsule form. 
  • Liquids: For herbs that have a pleasant flavor or don’t tolerate drying and grinding well, liquid concentrates can be an excellent choice. Some supplements are designed for mixing in drinks, while others are intended for sublingual use. With a calibrated dropper, this form of supplement is easy to take or to give to people who have trouble with pills.
  • Drinks and Powders: A new way to incorporate botanical supplements is in powdered drink mixes. Green juice powders and protein blends that contain herbs can be enjoyed alone or in other drinks such as smoothies or teas.

Herbal Supplement Safety

By taking herbal supplements instead of over-the-counter or prescription medications, many people feel they’re getting a gentler and more natural form of an active ingredient, but not all herbs are the same. Some plants grow with a greater concentration of active ingredients during some seasons than others, so dosage may be different from batch to batch. The efficacy of herbs has also not been as thoroughly tested as a medication that has gone through full FDA approval. Herbal tonics and supplements designed to support overall health may also contain caffeine or other stimulants, so read ingredient lists carefully. 

The Harvard Heart Letter makes the following recommendations when choosing an herbal supplement: 

– Try one-ingredient supplements to learn what works well for you. Single ingredients are also more likely to be targeted at your specific health concerns, so you’ll quickly learn if the product does what it’s intended to do for you. 

– Discuss herbal supplements with your physician to avoid any potential interactions with medicines or other supplements you already take. 

– Buy products with the USP or NSF label. The U.S. Pharmacopeia mark shows that the product has been tested for quality, uniformity and purity. The NSF stamp assures you that the supplement contains exactly what the ingredient list shows. 

Nutritional Supplements

The third category of supplement includes all the protein powders, juice concentrates and other products that contain macronutrients as well as micronutrients and botanicals. These products are designed to add nutritional value to your daily diet and typically contain calories, unlike vitamins and herbal supplements. 

Protein Powders and Smoothies

Protein is essential to building muscle tissue and maintaining good health, yet not everyone gets enough protein through diet alone. Supplements could be the answer here, and the protein in them comes from a wide range of sources to fit any dietary need. Whey protein is the most common form, but for those who don’t include dairy products in their diet, peas, rice, hemp and soy are other alternatives.

In addition to the protein itself, most protein drink mixes also contain ingredients to improve the taste and texture, including soluble fiber to thicken the drink and flavors to give it variety. Some powders contain sugars, including fructose and glucose, that could increase the calorie count and provide more food energy. That isn’t necessarily a drawback if you’re bulking, but if you’re enjoying protein powders as part of a weight maintenance plan, you may want to be aware of the calorie count. 

Some powders are meant to be blended with water, milk or soy milk by themselves. Others are intended to sprinkle into a smoothie to add nutritional value to it. A pre-sweetened or flavored mix, for example, may not work well in an already sweet and flavorful fruit smoothie. Read ingredient labels carefully to find a product that matches how you plan to use it. 

Total Nutrition Formulas

Protein powders that also contain botanicals, vitamins and minerals claim to offer total nutrition in a glass. They’re convenient for athletes who are actively training and for busy professionals but keep an eye on how these supplements work with any other formulas you might be taking. Doubling up on fat-soluble vitamins could give you too much of a good thing, and interactions between herbal supplements or other medications could have an impact on your health. If you’re looking to a total nutrition product as a meal replacement, talk with your doctor first to verify that this choice is a healthy one for you. 

The Science of Supplements

Vitamin and mineral supplements can have a powerful protective effect for anyone who’s missing vital nutrients, but the science is less clear about what other kinds of nutritional supplementation can do for you. Evidence for the value of omega-3 supplements derived from fish oil or flax suggest some protective value for your heart, while calcium supplements are known to help protect against bone density loss and osteoporosis. However, a recent study concluded that the most popular vitamins and supplements have no health effect at all. Ultimately, though, supplements are meant to add to what’s already there. Supplements aren’t substitutes, as Harvard’s Health Review points out, so it’s important to eat a balanced and varied diet of whole foods whenever possible.

Most popular vitamin and mineral supplements provide no health benefit

A new study found that the most common and popular supplements simply don’t do anything for you, with the exception of folic acid for reducing stroke risk.

Instead of supplements, researchers suggest implementing a healthy diet.

There are many misconceptions about vitamins and dietary supplements, and often times, product advertisements don’t really have the science to back them up. Vitamins and minerals, in particular, have long been used to treat nutrient deficiencies, and in recent years, a wide array of supplements has been hailed as a means for overall health and longevity. But is this really the case? A new study says ‘no’.

The study reviewed 179 trials on vitamin and mineral supplement use published in English from January 2012 to October 2017. They found that multivitamins, vitamin D, calcium and vitamin C — the most common supplements — showed no advantage or added risk in the prevention of cardiovascular disease, heart attack, stroke or premature death. Even researchers were surprised to see just how little of a difference these supplements made.

“We were surprised to find so few positive effects of the most common supplements that people consume,” said Dr. David Jenkins, the study’s lead author. “Our review found that if you want to use multivitamins, vitamin D, calcium or vitamin C, it does no harm – but there is no apparent advantage either.”

The one thing which seemed to work as intended was folic acid. Folic acid is a B-complex vitamin needed by the body to manufacture red blood cells. A deficiency of this vitamin causes certain types of anemia (low red blood cell count). Researchers found that acid supplements may reduce both cardiovascular disease and stroke risk.

“Folic acid administration and the reduction of cardiovascular disease through stroke seen in the Chinese CSPPT trial provides the only example of cardiovascular disease risk reduction by supplement use in the period following the Preventive Services Task Recommendation,” said Jenkins. “Whether these data are sufficient to change clinical practice in areas of the world where folic acid food fortification is already in place is still a matter for discussion.”

So what does this mean? Researchers suggest that in the absence of significant evidence, people shouldn’t focus on dietary supplements, and instead get their vitamins and minerals from a healthy diet. This is particularly significant since according to the National Health and Nutrition Examination Survey, in 2012, 52 percent of the population were taking supplements.

“So far, no research on supplements has shown us anything better than healthy servings of less processed plant foods including vegetables, fruits and nuts,” Jenkins concludes.

The US Dietary Guidelines recommend three diets to reduce heart disease risk, all of which emphasize fruits and vegetables, and a reduction in meat and dairy:

  • a healthy American diet low in saturated fat, trans fat and red meat, but high in fruit and vegetables;
  • a Mediterranean diet;
  • and a vegetarian diet.

The study has been published in The Journal of the American College of Cardiology