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This blog post is about the Vitamins A,C,D,E and K and the deficiencies associated with them…
Vitamin A and Night Blindness
The orange and yellow colors of carrots and other brightly colored fruits and vegetables are due to beta-carotene and several other related chemicals called carotenoids.
Your body can convert some of these carotenoids to retinol, which is the form of vitamin A that your body uses.
Human beings can easily get all the vitamin A they need by eating dark green and deep yellow or orange fruits and vegetables.
Cats, on the other hand, need to get their vitamin A in the form of retinol, which comes only from an animal source.
If you wanted to develop a plant-based diet for a cat, you would have to supplement it with some synthetic retinol (among other things).
One of the symptoms of mild vitamin A deficiency is night blindness, or the inability to see in low light conditions.
Severe vitamin A deficiency causes permanent blindness and problems with the immune system.
The safest way to meet your need for vitamin A is to eat dark green or deep yellow or orange vegetables and fruits.
Your body converts the carotenoids from those foods to vitamin A only on an as-needed basis.
Even if you overdose on carrot juice, the worst that’s likely to happen is that your skin will turn yellow.
On the other hand, an overdose of retinol can cause severe side effects, such as permanent blindness or even death.
Many Americans aren’t getting the recommended amount of vitamin A, but that’s mainly because most of us need to eat more fruits and vegetables.
Unfortunately, our agricultural subsidies are being spent on corn and soybeans instead of on fruits and vegetables. These subsidies are promoting the production and consumption of animal-based foods and processed foods.
So our tax dollars are being used to make dangerous food cheap, instead of making healthy food affordable.
Although most Americans would benefit from eating more fruits and vegetables, a severe vitamin A deficiency is actually rare in the United States.
Most cases occur in people who do not or cannot eat properly (such as alcoholics) and in people with digestive diseases (such as cystic fibrosis) that prevent them from absorbing vitamins from their food.
In contrast, vitamin A deficiency is a major cause of blindness and death among children in poor countries. Today, children in poor countries may receive a periodic high-dose vitamin A supplement, often in coordination with vaccination programs.
When people get a lot of beta-carotene from their diet, it is because they’re eating a lot of fruits and vegetables. This tends to make them healthier than the people who are eating the standard American diet.
Some people hoped that they could get the same benefits by adding beta-carotene in pill form to the standard American diet, instead of switching to a healthy diet. However, the beta-carotene supplement seems to do more harm than good.
One large clinical trial (the CARET study) involving people at high risk for lung cancer showed more lung tumors, more heart attacks, and more deaths among the subjects who received pills containing beta-carotene and retinyl palmitate (another form of vitamin A) than in patients who received placebo pills.
Why did the beta-carotene supplement do more harm than good?
In nature, there’s no such thing as a concentrated dose of pure beta-carotene. Fruits and vegetables provide beta-carotene in combination with other carotenoids.
Your body probably needs a balanced mixture of several carotenoids, not a concentrated dose of only one of them. The results of the CARET study reinforce a message that I have seen in every nutrition textbook I have ever read.
You should get your vitamins from foods, not from pills.
Vitamin C and Scurvy
When most people think of vitamin deficiency, the first thing they think of is scurvy, which results from a deficiency of vitamin C.
Scurvy became a particularly serious problem for sailors on long sea voyages. The food that could be stored for long periods on ships included a dried bread called hardtack and salted meat or fish.
None of those foods contain much vitamin C. In general, dried seeds such as stored grains don’t contain vitamin C. Of course, as soon as a seed sprouts, the sprout starts producing its own vitamin C.
All plants and most animals make their own supply of vitamin C. Human beings, gorillas, and guinea pigs are among the few species that cannot make their own vitamin C.
Lack of vitamin C causes severe problems with the connective tissue. The gums bleed and the teeth become loose and eventually fall out. The person bruises easily.
If the condition goes untreated, the person will eventually die of massive internal bleeding. Yet scurvy can be cured rapidly if the person starts eating fresh fruits and vegetables again.
Even sprouted beans or grains would have worked. To prevent scurvy, the British Royal Navy added citrus fruits to their sailors’ rations, which is why British sailors were called limeys.
A serious outbreak of scurvy occurred among bottle-fed babies in the United States in the 1890s, when dairies started pasteurizing cow’s milks.
Although the pasteurization killed dangerous bacteria, it also destroyed the vitamin C in the milk The scurvy could be prevented or cured by giving the baby a little bit of fresh fruit juice.
The take-home lesson is not that children should be drinking raw cow’s milk, which poses many serious health risks. It’s that babies should be breast-fed by their well-nourished mother.
The fact that we human beings have lost the ability to make vitamin C is a clue that we should be eating fruits and vegetables. Somewhere along the line, our ancestors lost the genes that would enable them to make vitamin C.
They could afford to lose those genes because they could always get plenty of vitamin C from the fruits and vegetables they were eating.
It wasn’t until people started trying to get by on nothing but stored grains and preserved meats that they ran into trouble with scurvy. Today, scurvy is rare in the United States.
Most cases nowadays occur in alcoholics and in elderly men who live alone and cook for themselves. The best way for most people to ensure that they get enough vitamin C is to eat fresh fruits and vegetables.
Vitamin D is not a true vitamin.
Instead, it is a hormone that is produced when ultraviolet light strikes the skin.
Unfortunately, an indoor lifestyle and overuse of sunscreen can pose a risk of vitamin D deficiency.
Furthermore, many Americans live much further north than their ancestors did. Thus, many Americans may have darker skin than is optimal for the climate where they now live.
The result has been cases of vitamin D deficiency among African-Americans in the North, especially among breast-fed babies.
Vitamin D is involved in how the body handles calcium. In children, a severe deficiency of vitamin D causes a bone deformity called rickets.
In adults, severe vitamin D deficiency can cause osteomalacia, which is a softening of the bones. The traditional cure for rickets was cod-liver oil, which is rich in vitamin D.
Eventually, people realized that sunlamps, which produce ultraviolet light, could also prevent and cure rickets. Yet the best way to get vitamin D is by getting reasonable exposure to natural sunlight.
For a white person in Boston, that means about 5 minutes of midday sunlight on the face, arms, and hands twice a week during the spring, summer, and fall. If you stay out in the sun too long, you could get a sunburn or increase your risk of wrinkling and skin cancer.
However, nobody has ever gotten an overdose of vitamin D from sunshine. In contrast, many people have gotten sick from vitamin D supplements.
To evaluate a patient’s vitamin D stores, doctors often use a blood test for 25-hydroxy-vitamin D, which is the form of vitamin D that is stored in the liver.
However, there is a lot of disagreement about what the normal level should be. Also, the results of the test can be misleading, for several reasons. One is that inflammation can suppress the amount of 25-hydroxy-vitamin D that is circulating in the bloodstream.
Also, vitamin D dissolves in body fat. As a result, the body fat of obese people tends to pull the 25- hydroxy-vitamin D out of the bloodstream
Thus, a low vitamin D level in a blood test does not necessarily mean a shortage of vitamin D in the body.
For these reasons, the results of vitamin D tests are hard to interpret. Dr. John McDougall recommends that people get as much sun exposure as they can tolerate without skin damage. He also recommends that people eat a starchy, low-fat, purely plant-based diet.
Such a diet will help to prevent the diseases (such as osteoporosis) that people hope to prevent through vitamin D supplementation. By relieving inflammation, this diet may also cause vitamin D levels in the bloodstream to rise to the levels that are considered normal.
Vitamin E was discovered by feeding rats an extremely abnormal diet. When young rats were fed a diet whose only fat source was lard, they lost the ability to reproduce.
The problem could be solved by adding wheat germ or lettuce to the diet. Eventually, the vitamin E effect was found to be the result of a family of fat-soluble compounds that were named tocopherols (from die Greek words meaning “to carry a pregnancy’) because of their importance in reproduction.
Unlike die other vitamins, vitamin E does not seem to play an important role in any of the body’s metabolic functions.
Instead, it seems to work as an antioxidant, preventing reactive chemicals called free radicals from causing a dangerous chain reaction.
No actual cases of vitamin E deficiency have ever been seen to result from people eating normal foods that are low in vitamin E.
The only known cases have been in people who cannot absorb fat-soluble vitamins from their food (because of a digestive disease) and people who have abnormally high requirements for vitamin E (because of an inherited metabolic disease).
Since vitamin E acts as an antioxidant, many people hoped that large doses of vitamin E would help prevent atherosclerosis (the buildup of crud in the arteries).
However, the results of trials of vitamin E supplementation for this purpose have been confusing.
In contrast, studies of a low-fat, plant-based diet for preventing heart disease have provided consistent, clear, excellent results. The less fat you eat, the less vitamin E you probably need.
Unless you have one of those rare digestive or metabolic diseases, you have no need to worry about getting enough vitamin E from a diet based on unrefined plant foods.
Vitamin K was discovered because it plays an important role in blood cloning (the K comes from the German word Koagulation).
It was later found to have an important role in bone formation. Vitamin K isn’t just one chemical. A large number of similar compounds can all have vitamin K activity.
The ones produced by green plants are called vitamin K1. The ones produced by the bacteria in our intestines are called vitamin K2.
There’s also a synthetic version, called vitamin K3, which our liver can convert to vitamin K2.
When people have a deficiency of vitamin K, their blood won’t clot properly. This increases the risk of major bleeding, even from a minor injury.
Fortunately, vitamin K deficiency is rare (except in newborns!) because human beings can get vitamin K from the bacteria in their intestines.
Most cases of severe vitamin K deficiency occur in people who have no bacteria in their intestines. Thus, it tends to occur in people who have been on powerful antibiotics. It used to be common in newborn babies.
But nowadays, most newborn babies receive a shot of vitamin K at birth.
All babies are born with a deficiency of vitamin K. Vitamin K does not pass easily through the placenta. Also, there is very little vitamin K in breast milk.
Babies have no bacteria in their intestine at first. Thus, they have no source of vitamin K. Because of this natural deficiency of vitamin K, babies are at risk for severe, life-threatening bleeding, including bleeding into the brain or other vital organs.
This condition is called classic hemorrhagic disease of the newborn.
The bleeding can happen very quickly, and the results can be devastating.
Nowadays, babies in the United States are routinely given a shot of vitamin K at birth. The vitamin K is given by injection because giving the vitamin K by mouth sometimes fails to provide adequate protection.
Vitamin K also serves as the antidote to warfarin (Coumadin), which is a commonly used blood thinner. People who are taking warfarin have to keep their intake of vitamin K stable.
If they make a change in their diet, their warfarin dosage will have to be adjusted. The sad part is that in many cases, people are taking the warfarin because of the damage that their bad diet has done to their heart muscle and blood vessels.
If they had kept their cholesterol low and avoided constipation, many of them would have avoided the disorders that led to a need for warfarin.
So now you realize that Vitamins are simply vital and it is important that you eat foods rich in vitamins and not only protein or good fats as popularized by the fitness frenzy!
Also, eating a completely plant-based diet will not rob you of any Vitamins; rather some plant sources are the best sources of particular Vitamins!