Vitamins A, B, C, D, E & K
Vitamin C is a vitamin. Some animals can make their own vitamin C, but
people must get this vitamin from food and other sources. Good sources
of vitamin C are fresh
Most experts recommend getting vitamin C from a diet high in fruits and vegetables rather than taking supplements
Fresh-squeezed orange juice or fresh-frozen concentrate is a better
pick than ready-to-drink orange juice. The fresh juice contains more
active vitamin C. Drink fresh-frozen orange juice within one week after
reconstituting it for the most benefit. It you prefer ready-to-drink
orange juice, buy it 3 to 4 weeks before the expiration date, and drink
it within one week of opening.
Historically, vitamin C was used for preventing and treating scurvy.
Scurvy is now relatively rare, but it was once common among sailors,
pirates, and others who spent long periods of time onboard ships. When
the voyages lasted longer than the supply of fruits and vegetables, the
sailors began to suffer from vitamin C deficiency, which led to scurvy.
These days, vitamin C is used most often for preventing and treating the common cold
. Some people use it for other infections including gum disease, acne and other skin infections,
, human immunodeficiency virus (HIV) disease, stomach ulcers caused by bacteria called
dysentery (an infection of the lower intestine), and skin infections
that produce boils (furunculosis). It is also used for infections of the
disease, physical and mental stress, fatigue, and attention deficit-hyperactivity disorder (ADHD).
Other uses include increasing the absorption of iron from foods and
correcting a protein imbalance in certain newborns (tyrosinemia).
There is some thought that vitamin C might help the heart and blood
vessels. It is used for hardening of the arteries, preventing clots in
veins and arteries,
Vitamin D is a vitamin. It can be found in small amounts in a few foods,
including fatty fish such as herring, mackerel, sardines and tuna. To
make vitamin D more available, it is added to dairy products, juices,
and cereals that are then said to be “fortified with vitamin D.” But
most vitamin D – 80% to 90% of what the body gets – is obtained through
exposure to sunlight. Vitamin D can also be made in the laboratory as
Vitamin D is used for preventing and treating rickets, a disease that is caused by not having enough vitamin D (
). Vitamin D is also used for treating weak bones (
), bone pain (osteomalacia), bone loss in people with a condition called hyperparathyroidism, and an inherited disease (
) in which the bones are especially brittle and easily broken. It is also used for preventing falls and
in people at risk for osteoporosis, and preventing low
and bone loss (renal osteodystrophy) in people with
Vitamin D is used for conditions of the heart and blood vessels, including
. It is also used for
, muscle weakness,
, chronic obstructive pulmonary disease (COPD),
and gum disease.
Some people use vitamin D for skin conditions including
, actinic keratosis, and lupus vulgaris.
It is also used for boosting the immune system, preventing
, and preventing
Because vitamin D is involved in regulating the levels of minerals such
as phosphorous and calcium, it is used for conditions caused by low
levels of phosphorous (
and Fanconi syndrome) and low levels of calcium (
Vitamin D in forms known as calcitriol or
is applied directly to the skin for a particular type of psoriasis.
Vitamin E is a vitamin that dissolves in fat. It is found in many
foods including vegetable oils, cereals, meat, poultry, eggs, fruits,
vegetables, and wheat germ oil. It is also available as a supplement.
Vitamin E is used for treating vitamin E deficiency, which is rare, but
can occur in people with certain genetic disorders and in very
low-weight premature infants.
Some people use vitamin E for treating and preventing diseases of the
heart and blood vessels including hardening of the arteries,
, leg pain due to blocked arteries, and
Vitamin E is also used for
and its complications. It is used for preventing cancer, particularly lung and
and polyps; and gastric,
Some people use vitamin E for diseases of the brain and
including Alzheimer’s disease and other dementias, Parkinson’s disease, night cramps,
, and for epilepsy, along with other
. Vitamin E is also used for Huntington’s chorea, and other disorders involving nerves and muscles.
Women use vitamin E for preventing complications in late
due to high
(PMS), painful periods, menopausal syndrome,
, and breast cysts.
Sometimes vitamin E is used to lessen the harmful effects of medical treatments such as dialysis and
. It is also used to reduce unwanted side effects of drugs such as
in people taking
and lung damage in people taking
Vitamin E is sometimes used for improving physical endurance, increasing energy, reducing muscle damage after
, and improving muscle strength.
Vitamin E is also used for
, asthma, respiratory infections, skin disorders, aging skin, sunburns,
, for certain inherited diseases and to prevent
Some people apply vitamin E to their skin to keep it from aging and to
protect against the skin effects of chemicals used for cancer therapy
The American Heart Association recommends obtaining antioxidants, including vitamin E, by eating a well-
high in fruits, vegetables, and whole grains rather than from
until more is known about the risks and benefits of taking supplements.
How does it work?Vitamin
E is an important vitamin required for the proper function of many
organs in the body. It is also an antioxidant. This means it helps to
slow down processes that damage cells.
Vitamin K is VITAL to the blood
clotting process that stops you bleeding to death from injury. It helps
to prevent fractures and has been linked to protective effects against
coronary heart disease and some types of cancer. It may have a role to
play in the brain and cognitive health.
Keep reading if you care about
- Not bleeding to death
- Preventing fractures
- Protecting against heart disease
- Brain health
- Looking good naked
K shares a number of similarities with vitamin D. Both substances are
fat-soluble. Like vitamin D, vitamin K is important for bone health.
Also like vitamin D, vitamin K has been studied for almost a century in
relation to one particular area of health (blood clotting), while recent
studies have suggested a much wider role in the body.
people confuse vitamin K with potassium, because the chemical symbol
for potassium on the periodic table is K. These are NOT the same
substances and have very different effects in the body.
will show you why your mother was right about eating greens – they
really are good for you – and why eating the whole animal makes sense
from both a vitamin K perspective and evolutionary perspective…. Organ
meats, anyone? Yummy.
The detailed version starts below, if you are in a hurry, you can skip all the science stuff if you want and go straight to the recommendations part, which will be marked like this
BUT that would be boring and you won’t learn much.
For those sticking with me, let’s get to it.
First, some science background.
What is Vitamin K
K is best known for its crucial role in blood clotting. Its name
actually comes from the German ‘Koagulationsvitamin’, or ‘coagulation
vitamin’, although vitamin K plays a role in anticoagulation and many
other physiological functions as well.
K is a fat-soluble vitamin, along with vitamins A, D, and E. Vitamin K
is not one substance but rather a group of compounds with a similar
chemical structure. The two naturally occurring forms identified so far
are vitamin K and K and both are biologically active in animals and humans.
Vitamin K is found in green plants, where it plays a role in photosynthesis.
- The richest dietary sources of vitamin K
(400-700 mcg/100g) are the dark green leaves of kale, spinach,
collards, Swiss chard, broccoli, Brussels sprouts, parsley, cabbage,
mustard greens, and turnip greens.
- Vitamin K can also be found in soybean, olive and rapeseed oils (50-200 mcg/100g).
Vitamin K is primarily made by bacteria.
- Bacteria in the human gut produce long-chain subtypes of vitamin K, but it remains unclear how much of this we absorb.
- The vitamin K subtype menaquinone-7 (MK7) is found in foods produced by bacterial fermentation like natto (fermented soybeans) and cheese.
- Human and animal tissues such as the brain and arterial walls convert vitamin K into a different subtype of vitamin K, menaquinone-4 (MK4).
- Dietary sources of MK4 include egg yolks, liver and other organs, and (to a lesser extent) meat.
Synthetic forms such as vitamin K are toxic and to be avoided.
Babies derive vitamin K and K from their mothers’ milk (or from formula if you are unlucky).
- Vitamin K compounds all have a methylated naphthoquinone ring structure.
- In photosynthesis, vitamin K (phylloquinone) acts as an electron acceptor during the electron transport chain in Photosystem I.
- In bacterial anaerobic respiration, vitamin K (menaquinone) transfers electrons between enzyme complexes in the electron transport chain.
- Cruciferous vegetables belonging to the Brassica genus contain particularly high levels of vitamin K.
- Vitamin K is called phylloquinone, phytonadione or phytomenadione.
- Vitamin K is called menaquinone or menatetrenone.
- Vitamin K is called menaphthone or menadione.
Completely random side-note.
Whenever I hear the word K2 I can’t help but envisage the MOUNTAIN of the same name in the Himalayas.
for being the second highest mountain in the world and also the second
deadliest taker of lives (as big mountains go), this thing is a beast
and is considered one of the world’s most difficult summits to climb.
Two movies about it I remember are K and Vertical Limit, but I digress.
Vitamin K and K
are necessary for an important chemical process called carboxylation
that allows certain important proteins to function properly. Without
vitamin K, these Gla proteins, also known as vitamin K-dependent
proteins, would not be able to bind calcium and interact with cell
referred to with a traffic light analogy, after speaking about it with
my sister, we decided that perhaps the best analogy was your local
of the postal system. Without stamps (calcium), chances are the
envelopes and parcels (Gla proteins) in the mail won’t reach their
destinations (tissues throughout the body). When mail doesn’t get
delivered, especially crucial mail, life can suck.
good folks at the Postal Service put the correct stamps in the correct
place at the correct time in the correct amount on your mail, ensuring
that the system works well (this is the role of vitamin K and associated
Vitamin K-dependent proteins play important roles in tissues throughout the body.
Their function is still being understood and is a growth area in science – my bet: vitamin K and K will have many surprises in store for us yet as the science evolves.
- Vitamin K compounds all have a methylated naphthoquinone ring structure.
- Vitamin K is a cofactor for the enzyme gamma-glutamyl carboxylase.
enzyme converts the glutamate (Glu) units or residues of vitamin
K-dependent proteins into gamma-carboxyglutamate (Gla) residues that are
able to bind calcium.
binding of calcium ions is essential to the Gla proteins’ structure and
function, facilitating interaction with phospholipids such as cell
is the first stage in wound healing and causes bleeding to stop via the
blood clotting cascade. Vitamin K (especially K) is essential to this process.
prescribed to prevent thrombosis such as warfarin act by blocking the
action of vitamin K in all in forms. Warfarin decreases the
concentration of vitamin K in body tissues and results in clotting
factors with inadequate Gla. People taking warfarin or other vitamin K
antagonists need to be especially careful and consistent with their
vitamin K intake – please consult your doctor if you are on these
severe vitamin K deficiency results in bruising and bleeding. It is
very rare in adults, but can sometimes occur in newborn babies. This is
because vitamin K and K are not easily transported across the placenta and the baby’s intestines have not yet been colonized with vitamin K
-synthesizing bacteria. Some pediatricians recommend supplementation
with vitamin K for newborns, either orally or through an intramuscular
injection. However this is a controversial practice because some studies
suggested a correlation between newborn vitamin K supplementation and
childhood cancers such as leukemia, although a causal link has not been
the vitamin K-dependent blood clotting cascade proteins carboxylated in
the liver are coagulation factors II (prothrombin), VII, IX, and X, and
anticoagulant proteins C, S, and Z.
show that vitamin K has a protective effect against bone fractures and
that osteoporosis is associated with low levels of vitamin K.
Vitamin K may be more important than vitamin K in this regard, although some studies show also a beneficial effect of vitamin K on bone health:
- A number of clinical trials showed that supplementation with vitamin K (but not vitamin K) protects against fractures in the elderly, especially in post-menopausal women.
- In Japan the vitamin K subtype MK4 is recommended as a treatment for osteoporosis.
- Japanese people derive the vitamin K subtype MK7 through their dietary consumption of natto.
is inconsistent evidence on vitamin K’s effect on bone mineral density.
Some scientists suggest that vitamin K mediates its skeletal effects
through other mechanisms, perhaps through collagen metabolism.
Some of you have asked me about the interaction between vitamin K and vitamin D.
Both are important for bone health. For example, vitamin D’s active
form, calcitriol, regulates the synthesis of a protein called
osteocalcin, but vitamin K activates this protein into a form that can
bind calcium. The two vitamins also appear to have a synergistic effect.
A clinical study showed that healthy women who took combined vitamin K, vitamin D and calcium supplements showed greater increases in wrist bone mineral density than the women who took vitamin K only or vitamin D and calcium without vitamin K.
Want good bones, you don’t just need good Vitamin D status, you need to get some Vitamin K action.
nutritionists suggest that potential toxic effects of very high vitamin
D consumption are in fact only due to vitamin K deficiency, and
therefore they advocate co-supplementation as a way to increase total
vitamin D intake to higher levels. There is no rigorous evidence to
support the safety of this approach.
- Vitamin K-dependent proteins involved in bone metabolism include osteocalcin, matrix Gla protein and periostin.
- Vitamin K-dependent protein S is made by osteoblasts (bone-forming cells).
plays a role in bone mineralization and osteoblast and osteoclast
activity, and is used as a marker of bone formation.
- The vitamin K subtype MK7 induces more complete carboxylation of osteocalcin than vitamin K.
build-up of calcium (calcification) in the arterial walls decreases
their elasticity and increases the risk of clot formation. In
atherosclerosis (hardening of the arteries), calcification of the
atherosclerotic plaque occurs at a late stage of the disease.
K helps to prevent a build-up of calcium in the arteries. A number of
large, prospective cohort studies have shown that intake of K (but not K)
is associated with reduced risk of coronary heart disease and a
protective effect against calcification of the coronary and aortic
arteries. Vascular calcification is a potential side effect of taking
vitamin K-antagonists such as warfarin.
- The mechanism for vitamin K’s
action is likely to be through two vitamin K-dependent proteins that
are carboxylated within the blood vessels (rather than in the liver).
Gla protein is not only found in bone and cartilage, but also in blood
vessel walls and other soft tissues. In the arterial wall, it is
expressed in vascular smooth muscle cells and is a potent inhibitor of
- Gas6 affects vascular smooth muscle cell apoptosis (cell death) and movement.
K may have an effect on cell growth through the vitamin K-dependent
growth specific gene 6 protein, or Gas6, which promotes cell survival
and inhibits cell death. Gas6 protein binds and activates receptor
tyrosine kinases, enzymes that can stimulate cell replication and
cell lines in vitro, vitamin K has the opposite effect and inhibits cell
growth. Prospective studies in humans suggest that dietary intake of K (but not K)
is associated with a reduced risk of prostate and lung cancer. However,
rigorous clinical trials are needed to explore the potential effects of
vitamin K on cancer.
Central Nervous System
is possible that vitamin K in all its forms affects cognitive health
via the carboxylation of proteins involved in the brain and nervous
system. Vitamin K is involved in the biosynthesis of sphingolipids.
These complex lipids are a structural component of cell membranes
throughout the body and also play a role in cell signalling. They are
present in high concentrations in neuronal and glial cell membranes in
the brain. Two other vitamin K-dependent proteins are relevant here.
Gas6 protein is involved in cell signalling in both the central and
peripheral nervous systems and the anticoagulation protein S is
expressed in the brain.
Studies in rats suggest that vitamin K and K may trigger gene expression of alkaline phosphatase in gut epithelial cells.
By now you should have figured out that vitamin K and K can be obtained from the diet, and that our own bodies can make K from K. The bacteria living in our gut can also provide us with K
(as shown by vitamin K deficiency in people taking antibiotics). Both
forms of vitamin K are transported around the blood by lipoproteins.
K in both forms can be reused in the body because it undergoes a cycle
of oxidation and reduction (the vitamin K cycle). However, it is also
extensively metabolized in the liver and excreted in the urine and in
feces (in bile), which means that vitamin K levels need to be
continually replenished. Vitamin K is the major circulating form of vitamin K and vitamin K is the major form stored in the human liver. Vitamin K has a longer half life.
As outlined above, the two forms of vitamin K appear to have different physiological actions. Vitamin K
is preferentially used up by the liver in the synthesis of active blood
clotting factors, which may explain its low stores in the liver.
Vitamin K is linked with skeletal and cardiovascular health.
of deficiency include bleeding (including the gums and gut), heavy
menstruation, and bruising. Severe deficiency results in low levels of
carboxylated blood clotting factors and can lead to uncontrolled
you’re worried, have a blood test. High serum levels of
under-carboxylated prothrombin (coagulation factor II) can indicate
sub-clinical vitamin K deficiency. Remember the postal analogy? This is
like finding lots of mail without stamps.
Severe deficiency is very rare. People with the following conditions may be at risk of a sub-clinical vitamin K deficiency:
- Fat mal-absorption syndromes
- Inflammatory bowel disease
- Liver disease
- Pancreatic insufficiency
- Cystic fibrosis
- Anorexia and/or bulimia
- Chronic alcoholism
Newborn infants have a higher risk of vitamin K deficiency.
Drugs can affect vitamin K and K
levels in your body. For example, taking antibiotics is associated with
low levels. Conversely, large, sudden increases or decreases in vitamin
K or K intake can alter the effectiveness of warfarin and other anti-thrombotics.
you have any of these medical conditions or are on medication, PLEASE
seek your doctor’s advice before taking vitamin K supplements or
increasing your dietary intake.
Kiwi, I GET IT. Vitamin K IS Important – But what should I DO?
Clearly, vitamin K is important for the health of our blood, artery walls, and bones.
And vitamin K is likely to have a host of other physiological effects not yet elucidated by science.
question, food is first, and food is best. I advocate consuming vitamin
K in both of its forms through your DIET wherever possible.
remember that the bio-availability of vitamin K is improved by eating
fats and by adequate bile synthesis and fat absorption in the gut. Take
down some olive oil with that salad.
Strategically optimize your dietary intake of both K and K as they appear to have different effects in the body:
For vitamin K and blood health:
plenty of dark green vegetables, such as kale, spinach, collards,
Brussels sprouts, parsley and broccoli. When I’m eating out I often
order an extra side dish (or two) of spinach.
- Eat them alongside good fats and oils to increase bioavailability of the fat-soluble vitamins in the gut.
For vitamin K and bone and arterial health:
What Dose Is Best, Kiwi?
2001, the non-governmental organization the Institute of Medicine
published Adequate Intake (AI) recommendations for vitamin K of 120
mcg/day for men and 90 mcg/day for women.
can safely consume more than this in the diet if you want to, because
no cases of vitamin K toxicity have ever been reported, to my knowledge.
Please note that I’m talking here about the naturally occurring forms
vitamin K and K. Do NOT take synthetic vitamin K as it can harm you.
shown by the complementary effects of vitamin D and K on bone, the
fat-soluble vitamins can often act synergistic-ally. I recommend that
you optimize your intake of vitamins A, D, and K.
dietary sources for the fat-soluble vitamins tend to overlap, which is
helpful. You can get your vitamin A from the same leafy green vegetables
and liver that you’re going to eat for vitamin K and K intake, respectively.
your vitamin D from exposing your skin to sunshine, eating oily fish or
taking D3 supplements. For more information on vitamin D see my
Alrighty then mate?
Of course, the good folks at team Athletic Greens
were nice enough to put Vitamin K in the formula, but as always I want you to start with food. Athletic Greens is there for the supercharge component.
get eat your delicious dark green vegetables, eggs and organ meats to
ensure your vitamin K and A intake, and while you’re at it, get outside
for some sunshine and vitamin D.
“100% Focus On Happiness”
That is my mantra, and it starts with phenomenal health.
Chris “the Kiwi”
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