Vitamin K is the generic name for a family of structurally similar compounds, including vitamin K3 (also known as menadione), which is a synthetically produced form of vitamin K.
1. What is the role of vitamin K?
Vitamin K is important for blood clotting and bone health. It can also prevent the build-up of calcium in the tissues, organs, and blood vessels of people with or at risk of certain diseases, such as kidney disease, heart disease, and diabetes.
Vitamin K3 is a synthetic form of vitamin K, made from vitamin K. This is unlike the other two forms of vitamin K, vitamin K1, called phylloquinone, and vitamin K2, called menaquinone.
Vitamin K3 can be converted to K2 in the liver. Many animals can also convert vitamin K3 into active forms of vitamin K.
Although vitamin K3 is not legally sold as a supplement for humans due to safety concerns, it is commonly used in poultry and pig feed, as well as commercial pet foods for dogs and cats.
2. Is Vitamin K3 Harmful to Humans
Research from the 1980s and 1990s demonstrated that vitamin K3 destroys red blood cells.
Research from the 1980s and 1990s has shown that vitamin K3 is harmful to humans. These studies have linked vitamin K3 to liver damage and the destruction of oxygen-carrying red blood cells. For this reason, only vitamin K1 and K2 forms are available as dietary supplements and prescription drugs.
Despite the harmful effects of vitamin K3 in humans, the vitamin has not been shown to be harmful to pets or livestock when added to food at prescribed doses.
However, there is still controversy over whether K3 should be allowed in pet food, with some companies that do not add the vitamin claiming that their products are superior to others.
In both cases, the natural forms of vitamin K – K1 and K2 – have a low potential for toxicity in humans.
Therefore, the US National Academy of Sciences and the European Food Safety Authority (EFSA) have not established an upper limit for vitamin K. The upper limit is the highest amount of the nutrient that can be consumed without causing harmful effects in most people.
3. What are the effects of vitamin K3?
Despite its harmful effects in humans, vitamin K3 has demonstrated anti-cancer and anti-inflammatory properties in test-tube studies.
One test-tube study found that vitamin K3 killed human breast, colon, and kidney cancer cells by activating a specific protein.
The vitamin has also been shown to increase the production of reactive oxygen species, which are molecules that can damage or kill cancer cells.
Furthermore, some test-tube studies have shown that vitamin C and vitamin K3 work together to inhibit the growth and death of human breast and prostate cancer cells.
In addition to these anti-cancer properties, the vitamin may also have antibacterial effects. One test-tube study found that vitamin K3 inhibited the growth of Helicobacter pylori in the digestive system by reducing the bacteria’s ability to replicate.
While promising, more research is needed before any conclusions can be drawn about the safety or effectiveness of vitamin K3 in treating cancer or other diseases in humans.
Additionally, because vitamin K3 has been shown to cause harm in humans, any future research will need to consider whether the potential benefits of this vitamin for treating disease outweigh the risks.
4. How much vitamin K do you need?
Vitamin K is found in many foods so people can get all the vitamin K they need through their diet.
The National Academy of Sciences recommends that adult women consume 90 mcg of vitamin K per day and men 120 mcg.
On the other hand, the European Food Safety Authority (EFSA) recommends only 70 mcg for adults, or 0.5 mcg per pound (1 mcg per kg) of body weight per day.
These recommendations are based on the minimum amount of vitamin K needed to prevent signs of deficiency (bleeding). More research is needed in the future to determine the ideal amount of vitamin K to optimize bone health and prevent vascular calcification.
Because vitamin K is found in a wide variety of foods, most people can get enough of this vitamin through their diet.
Vitamin K1 is found naturally in foods such as green leafy vegetables including spinach, kale, and broccoli, as well as vegetable oils such as soybean and canola oil. Some fruits, such as blueberries and grapes, also contain this vitamin.
Vitamin K2 is found primarily in fermented foods such as sauerkraut and natto, a traditional Japanese dish made from fermented soybeans, and in poultry and pork products.
Good sources of vitamin K include: (Percent Daily Value (DV)).
- 3 ounces (85 grams) natto: 708% DV
- 1/2 cup (45 grams) bok choy: 335% DV
- 1 cup (28 grams) spinach: 121% DV
- 1 cup kale (21 grams): 94% DV
- 1/2 cup (44 grams) broccoli: 92% DV
- 1 tablespoon (14 mL) soybean oil: 21% DV
- 3/4 cup (175 mL) pomegranate juice: 16% DV
- 1/2 cup (70 grams) blueberries: 12% DV
- 3 ounces (84 grams) chicken breast: 11% DV
- 1 cup (35 grams) romaine lettuce: 12% DV
How well vitamin K is absorbed depends on the food source. For example, the vitamin K in leafy greens is tightly bound to plant cell organelles called chloroplasts. This makes it harder for your body to absorb vitamin K than vitamin K from oils or supplements.
However, leafy greens tend to be the dominant source of vitamin K in the American diet. You can increase your absorption of the vitamin from leafy greens by eating them with fats like oil, nuts, or avocado.
Since vitamin K can interfere with the effectiveness of blood thinners like Warfarin or Coumadin, you should talk to your doctor before taking these supplements or increasing your intake of vitamin K-rich foods.
