Vitamins are a number of chemically unrelated families of organic substances that cannot be synthesized by humans but need to be ingested in the diet in small quantities to prevent disorders of metabolism. They are divided into water-soluble and fat-soluble vitamins (table 1).More than 50 years ago, Henrik Dam of Denmark discovered an "antihemorrhagic factor" that was capable of reversing dietary-induced bleeding disorders in chicks [1]. The name "K" comes from the German/Danish word koagulationsvitamin (clotting vitamin) [2].In 1930, vitamin K was first isolated by Doisy and his colleagues, as well as by Dam, from alfalfa sprouts [3]. Until the 1980s, when chromatographic techniques were used, the mainstay of vitamin K isolation was through using chick bioassay [2].This topic review will focus on vitamin K. Overviews of the other fat-soluble vitamins, minerals and water-soluble vitamins are available elsewhere. (See "Overview of vitamin A" and "Overview of vitamin D" and "Overview of vitamin E" and "Overview of dietary trace minerals" and "Overview of water-soluble vitamins" and "Vitamin supplementation in disease prevention".)
Dietary vitamin K1 (phylloquinone or phytonadione) is found in green vegetables like spinach and broccoli (table 2) [4]. Gut micro-flora synthesizes vitamin K2 (menaquinones, including menatetrenone), which provides a portion of the dietary requirement of vitamin K [4]. Vitamin K2 has approximately 60 percent of the activity of vitamin K1, by weight, but bioavailability of both forms varies substantially depending on other intraluminal nutrients [5]. Word not found in the Dictionary and Encyclopedia. Please try the words separately: Some articles that match your query: Vitamin R (Leading Us Along) Vitamin-B12 dependent methionine synthaseThis article covers:Background of vitamin K after birthAre some babies at higher risk of HDN?What are the effects of giving vitamin K by injection?What are the effects of giving vitamin K orally?Why were breastfed babies thought to be at increased risk?Should women take vitamin K?Possible vitamin K deficiency symptoms to watch out for
In the UK, parents of new babies are routinely asked if their baby is to have supplementary vitamin K by injection or oral supplement, which is needed to make blood clot and prevent excessive internal bleeding. Compared with adults, newborn babies are born with low levels of vitamin K but the amount is normally sufficient to prevent problems. Some babies are at risk, however, because they don’t have sufficient vitamin K, and they have an increased risk of Haemorrhagic Disease of the Newborn (HDN), also known as Vitamin K Deficiency Bleeding (VKDB). While some babies are at a higher risk than others (see below), some babies who are at risk of bleeding don’t show any risk factors and, for this reason, the Department of Health recommends all babies are given vitamin K soon after birth, usually by injection. However, it is your choice as a parent to decline, if you wish; you can also opt for vitamin K to be given by mouth instead. HDN is a rare but very serious disease.
Half of all babies who have HDN have a haemorrhage into their brain (intracranial bleeding). This often causes brain damage, and the baby may die. In the 1950s and 1960s, it became standard practice for all babies to have an injection of vitamin K into a muscle. Later, in the 1980s, some health professionals and parents wondered if it was necessary to give vitamin K injections to every newborn baby. Instead, single doses by mouth became popular, and some babies, if they were not deemed to be at higher risk, were not given the supplement at all. A UK study published in 1991 confirmed that HDN was rare. The babies who had HDN were more likely to have liver disease or be breastfed. Then, in 1990 and 1992, studies were published that suggested a possible link between injected vitamin K and childhood cancers including leukaemia. This meant more babies were given vitamin K by mouth. The number of babies with HDN went up slightly as a result, perhaps because oral vitamin K is slightly less effective than when it is given by injection.
Since then, further studies have failed to find any link between injected vitamin K and childhood cancers of any type and, in 1997 an expert body for the UK Department of Health concluded that this was no longer a concern. Babies at increased risk of HDN include: This means that about a third of babies are at increased risk. Some studies suggest that many of the babies who develop bleeding have unseen problems with their liver. It is hard to spot these babies before they bleed, so vitamin K can be preventive. Giving vitamin K by injection probably keeps levels higher for longer, compared with vitamin K by mouth, as it remains stored in the muscle where it was injected. Problems from the injection are very uncommon but may happen, as with any injection. Babies can feel pain and, on rare occasions, may have an infection at the place where the injection goes in, or bleeding and bruising in the muscle. Mistakes are very occasionally made with the injection, and the wrong dose or drug may be given.
Oral vitamin K is given in three separate doses, over the first month of life. Studies have shown that sometimes, a dose is omitted, probably because it’s forgotten about, and this means full protection is not given. According to studies, HDN was more common among breastfed babies. We know vitamin K levels are higher in colostrum (the first milk you produce) than in mature milk. In the past, babies were not breastfed till some time after birth, and strict feeding routines were usual; this probably meant that babies got less vitamin K than nature intended. Nowadays, babies are usually breastfeed soon after birth, and they feed frequently for as long and as often as they want. This means they get more colostrum than they used to, reducing the risk of HDN. Formula milk has vitamin K added to it. Giving vitamin K to mums before and after they have their babies has been tried in small-scale studies. Vitamin K does go across the placenta and into breastmilk, but it does not seem to be sufficient to prevent HDN.
If your newborn bleeds, for example, if you find blood oozing from the cord stump, or if bleeding continues for some time after the ‘heel prick’ blood test, or if your baby has a nose bleed or unexplained bruising, then talk to your doctor or midwife. They need to be checked in case this bleeding is a sign of HDN. If your baby has jaundice lasting longer than two to three weeks or is producing pale poos and dark urine, you should raise it with your doctor or midwife, because this may be a sign of liver problems, which increases the risk of abnormal bleeding. NCT's helpline offers practical and emotional support in all areas of pregnancy, birth and early parenthood: 0300 330 0700. You might find attending one of NCT's antenatal courses or Early Days groups helpful. Make friends with other parents-to-be and new parents in your local area for support and friendship by seeing what NCT activities are happening nearby. You can read Vitamin K in Neonates: facts and myths by Giuseppe Lippi and Massimo Franchini (Blood Transfusion 2011; 9-4-9) for more information.