Popular Science | Learn about the important vitamin for the human body - Vitamin K

Vitamins are an essential topic when it comes to human health and nutrition. However, less often discussed is vitamin K. Although the body requires it in relatively small amounts, it plays a vital role in bone, cardiovascular and immune health, among other things.

History of Vitamin K

In 1929, Danish biologist Henrik Damm discovered a substance with blood coagulation function for the first time while studying the mechanism of cholesterol synthesis in hens. In 1934, he named it "vitamin K", which comes from the German word for "coagulation" - Koagulation. In the late 1930s, American Doisy isolated vitamin K and determined its chemical formula and structure. In 1943, they won the Nobel Prize in Physiology or Medicine.

Vitamin K family

Vitamin K can be divided into two categories based on its source: natural and synthetic. Natural vitamin K includes vitamin K1 and vitamin K2, while synthetic vitamin K includes vitamin K3, K4, K5, etc. At present, humans mainly use vitamin K1 and K2.

Vitamin K1 , also known as phylloquinone, is widely found in green plants and is an important source of vitamin K in our food. Its main function is to maintain normal blood coagulation.

Vitamin K2 , also known as menadione, is mainly synthesized by intestinal bacteria or present in fermented foods. It plays an important role in the human body, one of which is to assist in activating vitamin K-dependent proteins such as osteocalcin and MGP, avoiding the formation of calcification foci in blood vessels, thereby promoting the correct deposition of calcium in bones.

Guardian of health

1. Bone health

Vitamin K2 is essential for bone health. It promotes the activation of osteocalcin, increases the activity of osteoblasts, and inhibits the activity of osteoclasts. In addition, vitamin K2 has immunomodulatory effects and can inhibit the proliferation of T cells. Adequate intake of vitamin K2 is important for maintaining bone health and overall immune function.

Studies have shown that supplementation with phytomenaquinone or MK-4 (a form of vitamin K2) can improve bone density and significantly reduce the incidence of hip fractures, vertebral fractures, and all non-vertebral fractures [2].

Although intervention studies have found that calcium and vitamin D intake can affect research results [3], it is generally believed that adequate vitamin K intake is important for bone health, and the European Food Safety Authority has also approved the health claim that "a causal relationship has been established between dietary vitamin K intake and bone health."

Calcium, vitamin D3 and vitamin K2 are known as the "three musketeers" for maintaining bone health. Together they play a key role in ensuring strong and healthy bones.

2. Cardiovascular disease

Vascular calcification is a risk factor for coronary heart disease because it reduces the elasticity of the aorta and arteries [4]. Matrix Gla protein (MGP) is a vitamin K-dependent protein that may play a role in preventing vascular calcification. Vitamin K deficiency may lead to incomplete carboxylation of MGP, which may increase the risk of vascular calcification and coronary heart disease.

The Rotterdam Study showed that a high intake of vitamin K2 has a strong protective effect on heart health. In this study published in the journal Nutrition in 2004, it was found that people with a high intake of vitamin K had a 50% lower risk of heart disease, a 50% lower risk of cardiovascular disease, and a 20% lower probability of overall mortality compared to other groups [5].

Vitamin K2 plays an extremely important role in calcium metabolism, bringing calcium to where it should go and preventing calcium from being deposited where it should not go. By helping arteries stay healthy and flexible, vitamin K helps improve cardiovascular health, thereby improving vascular elasticity (i.e. the ability of the vascular system to relax and contract) and preventing atherosclerosis.

3. Other diseases

Vitamin K2 can improve type 2 diabetes by regulating osteocalcin levels, inhibiting inflammatory responses, and lowering lipids. In addition, there is a lot of research evidence showing that vitamin K also has potential benefits in fighting cancer, preventing and treating obesity and chronic kidney disease. These studies provide preliminary support for the role of vitamin K in the management of multiple diseases.

In summary, vitamin K plays an important role in maintaining bone health, preventing cardiovascular disease, and immune regulation. Maintaining an appropriate intake of vitamin K through a balanced diet or appropriate supplementation can help maintain the overall health of the body and prevent the occurrence of related diseases.

Who is deficient in vitamin K?

Under normal circumstances, vitamin K is not easily deficient. However, the following groups of people may be deficient in vitamin K:

① The newborn was not given vitamin K injection at birth;

② In addition, patients with chronic gastrointestinal diseases (cystic fibrosis, celiac disease, ulcerative colitis and short bowel syndrome) and those who have undergone weight loss surgery may have poor absorption of vitamin K.

Vitamin K2 is a very safe nutrient. Based on research data, the United States Pharmacopeia Convention concluded that "at usual intake levels, taking vitamin K2 (MK-7) dietary supplements does not pose a risk of serious events associated with personal or public health."

Food sources and intake

According to the latest Chinese Residents' Dietary Nutrient Reference Intake, the daily appropriate intake (AI) of vitamin K for adults is 80 micrograms (µg), which is applicable to adults aged 18 and above, including pregnant women. However, for breastfeeding mothers, some vitamin K will be lost through breast milk, so the intake is increased to 85 micrograms (µg).

Food sources

Green leafy vegetables are one of the main sources of vitamin K1, including kale, spinach, broccoli, cabbage and lettuce. These vegetables are rich in K1 and provide other nutrients. In addition, soybean oil and rapeseed oil are also good sources of K1.

Natto is the richest food source of vitamin K2. Natto is a traditional Japanese food made from fermented soybeans. It is rich in K2 and is a good choice for supplementing this vitamin. In addition, K2 is also found in foods such as meat, cheese and eggs, but in smaller amounts.

By taking these foods, you can effectively obtain different forms of vitamin K to meet the body's needs. For optimal nutrient absorption, it is recommended to have a diverse diet, including the food sources mentioned above, and to make a reasonable combination according to personal needs. If you cannot supplement enough vitamin K through natural foods, you can also consider vitamin K supplements, but it is best to consult a doctor or nutritionist before using them.

References

[1] Zhou Jianlie. Clinical Vitamin K2[M]. Peking Union Medical College Press, 2021.

[2]Cockayne S, Adamson J, Lanham-New S, et al. Vitamin K and the prevention of fractures: Systematic review and meta-analysis of randomized controlled trials[J]. Archives of Internal Medicine, 2006, 166(12): 1256-1261.

[3]Binkley N, Harke J, Krueger D, et al. Vitamin K Treatment Reduces Undercarboxylated Osteocalcin but Does Not Alter Bone Turnover, Density, or Geometry in Healthy Postmenopausal North American Women[J]. Journal of Bone and Mineral Research, 2009.

[4]Tintut DY. Vascular Calcification Pathobiology of a Multifaceted Disease[J]. Circulation: An Official Journal of the American Heart Association, 2008, 117(22).

[5]Geleijnse JM, Vermeer C, Grobbee DE, Schurgers LJ, Knapen MH, van der Meer IM, Hofman A, Witteman JC. Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study. J Nutr. 2004 Nov; 134(11): 3100-5. doi: 10.1093/jn/134.11.3100. PMID: 15514282.