Vitamin K is important for blood clotting and bone formation. It is synthesized by plants and bacteria, with the main forms being phylloquinone (from plants) and menaquinones (from bacteria). Humans obtain vitamin K primarily through dietary sources like green leafy vegetables, which contain phylloquinone, as well as from bacterial synthesis in the gut. However, vitamin K absorption can be limited, with only about 10% being absorbed from boiled spinach.

1. Domina Petric, MD
Significance and sources of vitamin K

2. Significance of vitamin K
• Vitamin K is synthesized by plants and
bacteria, which use it for electron
transport and energy production.
• Humans can not synthesize the vitamin,
but gut bacteria (good bacteria) can.
• Vitamin K is important for blood
clotting, bone formation and other
functions.
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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3. Vitamers K
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Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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4. Phylloquinones
Green plants synthesize the
phylloquinones (2-methyl-3-
phytyl-1,4-naphthoquinones)
as a normal component of
chloroplasts.
4/11/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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5. Menaquinones
• Bacteria (including those of the normal
intestinal microflora) and some spore-
forming Actinomyces spp. synthesize
the menaquinones.
• The predominant vitamers of the
menaquinone series contain 6 to 10
isoprenoid units.
• Vitamers with as many as 13 isoprenoid
groups have been also identified.
4/11/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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6. Menadione
• The formal parent compound of the
menaquinone series does not occur
naturally, but is a common synthetic form
called menadione (2-methyl-1,4-
naphthoquinone).
• This compound forms a water-soluble
sodium bisulfite addition product,
menadione sodium bisulfite, whose
practical utility is limited by its instability
in complex matrices such as feeds.
4/11/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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7. Menadione
• In the presence of excess sodium
bisulfite, it crystallizes as a complex
with an additional mole of sodium
bisulfite (menadione sodium bisulfite
complex), which has greater stability.
• A third water-soluble compound is
menadione pyridinol bisulfite (MPB), a
salt formed by the addition of
dimethylpyridinol.
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Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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8. Biopotency of vitamers K
When administered orally, phylloquinone or
menaquinone homologs with three to five
isoprenoid groups had greater activities
than those with longer side chains.
The difference in biopotency appears to
relate to the relatively poor absorption of
the long chain vitamers.
4/11/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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9. Dietary sources
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Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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10. Dietary sources
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Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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11. Canola (rapeseed) oil: 830 Vitamin K (µg/100 g)
Huffingtonpost.com
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Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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12. Spinach: 266 vitamin K (µg/100 g)
Fresh-square.com
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Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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13. Kale: 275 vitamin K (µg/100 g)
Medicalnewstoday.com
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Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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14. Cauliflower: 191 vitamin K (µg/100 g)
Draxe.com
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Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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15. Cabbage: 149 vitamin K (µg/100 g)
Organicfacts.net
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Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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16. Bioavailability
• Only about 10% of the phylloquione in
boiled spinach is absorbed by humans.
• This may relate to its association with the
thylakoid membrane in chloroplasts, as
the free vitamer was well absorbed (80%).
• Vitamin K may be poorly bioavailable from
the most quantitatively important sources
of it in most diets, green leafy vegetables.
4/11/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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17. Intestinal microbial synthesis
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Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
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18. • Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.
Literature
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