Vitamin K2 plays an essential role in the health of infants and is valuable for both children and the elderly where it exerts cardioprotective action, among other things. In addition to the well-known virtues of regulating blood clotting and bone health, and various other benefits.
A recent scientific review published in Children’s (Kozioł-Kozakowska A, Maresz, 2022) complements the copious scientific literature on a vitamin that the human body is unable to synthesize and must therefore take in through food. (1)
Vitamin K2 sources
Vitamin K (naphthoquinone) is fat-soluble and is distinguished into two types according to origin.
– K1 (phylloquinone), of plant origin and found mainly in green leafy vegetables, such as spinach, broccoli, lettuce, and Brussels sprouts.
– K2 (menaquinone) MK-7, which is bacterial in origin and present in high amounts in ‘natto,’ a Japanese dish made from fermented soybeans (on the cover). Its MK-4 form is also found in animal organs whose consumption is otherwise rare (liver, brain, kidney, pancreas).
Other important sources of 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 constitute valuable sources of vitamin K:
– dried nori(Porphyra sp., or laver) seaweed contains about 2600 μg/100 g vitamin K,
– The dried wakame(Undaria pinnatifida) and hijiki(Sargassum fusiforme) seaweeds contain 1293 μg/100 g and 175 μg/100 g of vitamin K1, respectively,
– 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, including anti-caries,
– cardiovascular health,
– brain development,
– joint health,
– Body weight control.
Scientific studies retraced by the review under review suggest vitamin K2 implementation as early as in some pathological conditions of childhood and adoloscence, such as:
– Fractures,
– Obesity,
– Cooley’s anemia,
– cystic fibrosis,
– Inflammatory bowel disease and liver disease,
– severe disability, often associated with malnutrition, malabsorption, changes in microbiota, and liver dysfunction.
Vitamin K2 dietary supplementation needed
In addition to the cited disease-related cases, a significant decrease in the intake levels of vitamin K and, in particular, vitamin K2, is caused by the nutritional depletion of Western dietary patterns over the past 50 years. With serious health consequences.
Exacerbating the situation are the therapies used in pediatric practice based on antibiotics and glucocorticoids for long periods:
– the former alter the gut microbiota by inhibiting vitamin K production,
– the latter cause significant reductions in bone formation, especially in the growing skeleton, inducing osteoporosis.
Risk of deficiency in infants
Vitamin K deficiency is common in infants. This is due to the poor synthesis of the vitamin because of a gut that is still poorly colonized by bacteria, the reduced passage of vitamin K across the placental barrier, and its low accumulation in breast milk (with the exception of new mothers in eastern Japan).
Such deficiency in the newborn can cause hemorrhage, even life-threatening hemorrhage. A safe form of prevention is a single intramuscular administration of vitamin K at birth, as recommended by the renowned Bambino Gesù Children’s Hospital, Rome, which explains ‘Such administration is recommended in all infants (and not just those with increased risk of hemorrhage. (4)
Vitamin K, the role in adulthood and for the elderly
Vitamin K-dependent proteins(VKDPs)-widely distributed in tissues, including outside the liver-are best known for their protective role in bones and the cardiovascular system. In addition to being involved in cell differentiation and proliferation, inflammation, and signal transduction.
Therefore, vitamin K deficiency has 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.
The study Rotterdam prospective-conducted in 4,807 subjects with no history of myocardial infarction and followed for 7 years-low levels of vitamin K2 (not also K1) were associated with a significant risk of coronary artery disease (Coronary heart disease, CHD), all-cause mortality, and severe aortic calcification. (5)
In the study of Prospect-EPIC cohort-which enrolled 16,057 women without cardiovascular disease (CVD), with a follow-up mean of 8.1 years-an inverse association was identified between vitamin K2 (specifically MK-7, MK-8, and MK-9) and CHD risk, 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.
EFSA’s Panel on Dietetic Products, Nutrition and Allergies (NDA) in its opinion of 5/22/17 confirmed the dietary reference values established by the Scientific Committee on Food in 1993.
Daily adequate intake amounts of vitamin K are given in:
– 10 µg for infants aged 7 to 11 months;
– 12 µg for children aged 1 to 3 years;
– 20 µg for children aged 4-6 years;
– 30 µg for children aged 7 to 10 years;
– 45 µg for children aged 11-14 years;
– 65 µg for adolescents aged 15-17 years and
– 70 µg for adults, including pregnant and lactating women. (7)
Marta Strinati and Dario Dongo
Cover image from Nippon.com, https://www.nippon.com/hk/japan-glances/jg00116/
Notes
(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 S. B. 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 macroalgae and microalgae species such as Porphyra sp. (Rhodophyta), Sargassum muticum, Sargassum fusiforme, Undaria pinnatifida, Nannochloropsis oculata (Ochrophyta), Tetraselmis suecica, Dunaliella salina, Desmodesmus asymmetricus, Chlorella vulgaris, Chlamydomonas reinhardtii (Chlorophyta), Isochrysis galbana, Pavlova lutheri (Haptophyta), Skeletonema costatum (Bacillariophyta). Several species of cyanobacteria – such as Anabaena cylindrica, Anabena variabilis, Spirulina sp. e Nostoc muscorum, Synechocytis sp – 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 J.M., Vermeer C., Grobbeehlight D.E., Schurgers L.J., Knapen M.H.J, Van Der Meer I.M., Hofman A., Witteman J.C.M. (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 G.C., de Roos N.M., Sluijs I., Botsnary M.L., Beulens J.W., Geleinse J.M., Witteman J.C, Grobbee D.E., Peeters P.H., van der Schouw Y.T. (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. 5/22/17 https://www.efsa.europa.eu/it/press/news/170522-1
Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
