Vitamin K2 plays an essential role in the health of newborns and is valuable for both children and the elderly, where it exerts, among other things, a cardioprotective action. In addition to the known virtues of regulating blood clotting and bone health, and various other benefits.
A recent scientific review published on Children (Kozioł-Kozakowska A, Maresz, 2022) integrates the copious scientific literature on a vitamin that the human body is unable to synthesize and must therefore be consumed through food. (1)
Vitamin K2, the sources
Vitamin K (naphthoquinone) is fat-soluble and is divided into two types according to the origin.
- K1 (phylloquinone), of vegetable origin and mainly present in green leafy vegetables, such as spinach, broccoli, lettuce, Brussels sprouts.
- K2 (menaquinone) MK-7, of bacterial origin and present in high quantities in 'natto', a Japanese dish based on fermented soybeans (on the cover). Its MK-4 form is also found in animal organs which are rarely consumed (liver, brain, kidneys, pancreas).
Other sources important in vitamin K2 are meat (especially chicken, bacon and ham), egg yolks and high-fat dairy products, such as hard cheeses.
Vitamin K in algae and microalgae
Algae and microalgae in turn they are valuable sources of vitamin K:
- nori seaweed (Porphyra sp.the laver) dried contains about 2600 μg / 100 g of vitamin K,
- wakame seaweed (Undaria pinnatifida) and hijiki (spindle-shaped sargassum), dried, respectively contain 1293 μg / 100 g and 175 μg / 100 g of vitamin K1,
- microalgae and cyanobacteria are also valuable sources of vitamin K (2,3).
Fig. 1 - Vitamin K in algae and microalgae (Simes et al., 2020. See notes 2,3).
Vitamin K2 and activation of essential proteins
Scientific research has now made it clear that vitamin K2 activates proteins that perform crucial biological functions:
- mineralization of bones and teeth, also for anti-caries function,
- cardiovascular health,
- brain development,
- joint health,
- body weight control.
Studies scientific retraces from the review in question suggest an implementation of vitamin K2 already in some pathological conditions of childhood and adolescence, such as:
- Cooley's anemia,
- cystic fibrosis,
- inflammatory bowel disease and liver disease,
- severe disability, often associated with malnutrition, malabsorption, changes in the microbiota and liver dysfunction.
Vitamin K2, necessary dietary supplement
In addition to the cases mentioned related to diseases, a significant decrease in the levels of vitamin K intake and, in particular, vitamin K2, is caused by the nutritional depletion of Western dietary patterns over the past 50 years. With serious health consequences.
To aggravate the situation the therapies used in pediatric practice based on antibiotics and glucocorticoids for long periods contribute:
- the former alter the intestinal microbiota by inhibiting the production of vitamin K,
- the latter cause significant reductions in bone formation, especially in the growing skeleton, inducing osteoporosis.
Risk of deficiency in newborns
Vitamin K deficiency it is common in newborns. This is due to the poor synthesis of the vitamin due to an intestine that is still poorly colonized by bacteria, the reduced passage of vitamin K through the placental barrier and its low accumulation in breast milk (with the exception of that of new mothers in eastern Japan).
Such a shortage in the newborn it can cause bleeding, even fatal. A safe form of prevention is a single intramuscular administration of vitamin K at birth, as recommended by the renowned Bambino Gesù pediatric hospital in Rome, which explains'This administration is recommended in all newborns (and not only in those with an increased risk of bleeding'. (4)
Vitamin K, the role in adulthood and for the elderly
Proteins which depend on vitamin K (vitamin K-dependent proteins, VKDPs) - widely distributed in tissues, even outside the liver - are best known for their protective role on the bones and cardiovascular system. In addition to being involved in cell differentiation and proliferation, inflammation and signal transduction.
The shortage Vitamin K has therefore been associated with various chronic diseases such as cardiovascular disease (CVD), chronic kidney disease, osteoarthritis, rheumatoid arthritis, osteoporosis, cancer, dementia, some skin diseases, functional decline and disability. Pathologies largely associated with pathological calcification and inflammation, where the role of VKDPs and vitamin K is highlighted.
A systematic review Rotterdam Prospectus - conducted on 4.807 subjects with no history of myocardial infarction and followed for 7 years - low levels of vitamin K2 (not also K1) have been associated with a significant risk of coronary heart disease (coronary heart disease, CHD), all-cause mortality, and severe aortic calcification. (5)
In the study Prospect-EPIC cohort - which enrolled 16.057 women without cardiovascular disease (CVD), with a follow-up mean of 8,1 years - an inverse association between vitamin K2 (particularly MK-7, MK-8 and MK-9) and risk of CHD was identified, with an 85-100% reduction in coronary events for each 10 µg increase in vitamin K2 intake. (6)
K2, safe and effective
In the MK-7 form, vitamin K2 has a documented history of safe and effective use in children and adults. The only possible contraindication is the use of anticoagulant drugs, such as coumarins, which can interfere with vitamin K.
The group of experts Scientific Committee on Dietetic Products, Nutrition and Allergies (NDA) of EFSA with the opinion of 22.5.17 confirmed the dietary reference values established by the Scientific Committee for Food in 1993.
The daily quantities of adequate vitamin K intake are indicated in:
- 10 µg for infants aged 7 to 11 months;
- 12 µg for children between the ages of 1 and 3;
- 20 µg for children between the ages of 4 and 6;
- 30 µg for children between the ages of 7 and 10;
- 45 µg for children aged 11 to 14;
- 65 µg for adolescents aged 15-17 e
- 70 µg for adults, including pregnant women and lactating women. (7)
Marta Strinati and Dario Dongo
Cover image from Nippon.com, https://www.nippon.com/hk/japan-glances/jg00116/
(1) Kozioł-Kozakowska A, Maresz K. The Impact of Vitamin K2 (Menaquionones) in Children's Health and Diseases: A Review of the Literature. Children. 2022; 9 (1): 78. https://doi.org/10.3390/children9010078
(2) Dina C. Simes, Carla SB Viegas, Nuna Araújo, Catarina Marreiros (2020). Vitamin K as a Diet Supplement with Impact in Human Health: Current Evidence in Age-Related Diseases. Nutrients. 2020 Jan; 12 (1): 138. doi: 10.3390 / nu12010138
(3) Vitamin K1 synthesis is reported in several species of macroalgae and microalgae such as Porphyra sp. (rhodophyta), Sargassum muticum, Sargassum fusiforme, Undaria pinnatifida, Nannochloropsis oculata (Ochrophyta), Tetraselmis suecica, Dunaliella salina, Desmodesmus asymmetricus, Chlorella vulgaris, Chlamydomonas reinhardtii (Chlorophyphytaum galactic (Chlorophyta) bacterium galtaphyroma (Chlorophyta), Isochreletonva costlophy Different species of cyanobacteria - like Anabaena cylindrica, Anabena variabilis, Spirulina sp. e Nostoc muscorum, Synechocytis sp - they are also described for their ability to biosynthesize and produce vitamin K1 (Simes et al., 2020)
(4) Bambino Gesù Children's Hospital. Vitamin K. https://www.ospedalebambinogesu.it/vitamina-k-89768/
(5) Geleiinse JM, Vermeer C., Grobbeehlight DE, Schurgers LJ, Knapen MHJ, Van Der Meer IM, Hofman A., Witteman JCM (2004). Dietary Intake of Menaquinone Is Associated with a Reduced Risk of Coronary Heart Disease: The Rotterdam Study. J. Nutr. 2004; 134: 3100-3105. doi: 10.1093 / in / 134.11.3100
(6) Gast GC, de Roos NM, Sluijs I., Botsnary ML, Beulens JW, Geleinse JM, Witteman JC, Grobbee DE, Peeters PH, van der Schouw YT (2009). A high menaquinone intake reduces the incidence of coronary heart disease. Nutr. Metab. Cardiovasc. Dis. 2009; 19: 504-510. doi: 10.1016 / j.numecd.2008.10.004
(7) Dietary reference values: EFSA publishes opinion on vitamin K. 22.5.17 https://www.efsa.europa.eu/it/press/news/170522-1