All about Vitamins

It can be easy to lose track of all the vitamins out there. It's even easier to forget how exactly they help our bodies. Let’s see, vitamin A heals wounds and vitamin C improves eyesight, wait, what was it again?  There are so many, it feels like there should be a vitamin Z. Here are the basics for vitamins, what they do and how to get them in healthy amounts.

Vitamin A

Function: As well as being necessary to new cell growth, vitamin A helps fight infections, and is essential for healthy skin, good blood, strong bones and teeth. It also plays essential roles in the kidneys, bladder, lungs and membranes, as well as helping maintain good eyesight. Vitamin A also helps eyes adjust to changes in levels of light.

Sources: Fish liver oils, liver, dairy products, carrots, cantaloupe, peaches, squash, tomatoes, and all green and yellow fruits and vegetables can fuel the body with vitamin A. Note: Many plants contain beta carotene, which the body converts into vitamin A. Dark green leafy vegetables and yellow and orange vegetables and fruits are excellent sources of beta carotene.

Recommended daily intake: It is recommended that women consume 800 mcg and men consume 1000 mcg of vitamin A daily. Like other fat-soluble vitamins, vitamin A can be harmful when too much is consumed. Too much can lead to toxicity and other health problems, including an increased risk of fractures in postmenopausal women, nausea, blurred vision, and irritation. In more severe forms of overconsumption, it can lead to hair loss, growth retardation, and an enlarged spleen and liver. Too little vitamin A (though rare in the United States) can lead to night blindness, eye inflammation, and diarrhea.

Vitamin B-6

Function: Vitamin B-6 helps the brain function at its peak and the body convert protein to usable energy. It is also needed for the production of red blood cells and antibodies.

Source: Meats, whole grain products, bananas, green leafy vegetables, pecans, eggs, and milk are excellent sources of B-6.

Recommended daily intake:  Women require 1.6 mg of B-6 daily, while men need 2 mg. Daily intake of over 250 mg can lead to nerve damage. Pregnant women should not take more than the recommended amount as it could harm a developing fetus. As a water-soluble vitamin, B-6 must be replenished each day. Any B-6 not used is eliminated in urine, thus new sources are always needed.

Vitamin B-12

Function:  Vitamin B-12 works with folic acid to produce healthy red blood cells. Also, it plays key roles in maintaining health of the nervous system, absorption of foods, protein synthesis, carbohydrate and fat metabolism, and normal digestion.

Sources: Liver, kidneys, muscle meats, fish, dairy products, meat, and eggs are all good sources of B-12.

Recommended daily intake: Both men and women need 2.0 mcg of B-12 daily. Because B-12 is water soluble, it is constantly lost in urine when not used and a steady supply is needed. B-12 deficiency can lead to a type of anemia, walking and balance problems, sore tongue, weakness, confusion, and in advanced cases, dementia. Pregnant or breastfeeding women should not take more than 2.6 mcg and 2.8 mcg of B-12, respectively. People over the age of 50 may need B-12 supplementation as the body's ability to absorb vitamin B-12 from food sources diminishes.

Vitamin C

Function: Vitamin C helps to heal wounds, prevent cell damage, promote healthy gums and teeth, strengthen the immune system, and absorb iron. It also helps neutralize free-radicals in cells that promote aging, fight bacterial infections, and aid in the production of red blood cells.

Sources: Fresh fruit and berries (especially citrus fruits), green vegetables, onions, tomatoes, radishes, and rose hips are all excellent vitamin C sources.

Recommended daily intake: Men and women should each consume at least 60 mg of vitamin C daily. Many things can increase the need of vitamin C in the body, including stress and smoking. For smokers, recommended intake increases to 110 mg for women and 125 mg for men. While not getting enough vitamin C can lead to scurvy, consuming more than 2000 mg on a daily basis can lead to headaches, increased urination, mild diarrhea, nausea, and vomiting. Pregnant and breastfeeding women should not take more than the recommended amounts of Vitamin C.

Vitamin D

Function: Vitamin D is important in helping the body use and absorb calcium. It is also necessary in the utilization of phosphorous. Also known as Calciferol, it promotes strong bones and teeth, prevents rickets, supports muscle and nerve function, and, some studies have shown, helps prevent osteoporosis.

Sources: Fortified milk and cereals, eggs, tuna, fish-liver oils, and sun exposure all help the body obtain vitamin D.

Recommended daily intake: Men and women aged 19-50 should consume at least 200 IU of vitamin D on a daily basis. People over the age of 50 should consume at least 400 IU daily, as the body's ability to convert sunlight to vitamin D decreases with age. While too little vitamin D can lead to weakened bones and an increased risk of fractures, too much vitamin D can cause nausea, vomiting, poor appetite, constipation, weakness, and weight loss. Prolonged exposure to too much vitamin D can lead to health problems and toxicity. If you take, antacids, some cholesterol lowering drugs, some anti-seizure medications, or steroids, know that they all interfere with the absorption of vitamin D.

Vitamin E

Function: Vitamin E acts as an antioxidant that prevents premature reaction to oxygen in the body and the breakdown of many substances in the body. It neutralizes free radicals in the body that would otherwise cause damage to cells and tissue, while aiding in circulation, clotting, and healing. Some studies have even shown that vitamin E decreases symptoms of premenstrual syndrome and certain types of breast disease. Other studies have shown that taking large doses of vitamin E has decreased the risk of Coronary Artery Disease.

Sources: Most vegetable oils, wheat germ, soybean oil, raw seeds and nuts, egg yolk, whole grain products, beef liver, peanut butter, and unrefined cereal products are good sources of vitamin E.

Recommended daily intake: Women need 8 mg and men require 10 mg of vitamin E on a daily basis. Though it's almost impossible to have a vitamin E deficiency, too much can cause nausea and digestive track problems. Prolonged overexposure can lead to toxicity and other health problems.
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Member Comments

Absolutely great Report
great article Report
very interesting Report
thanks Report
Very informative. Thanks for sharing. Report
Good article. Report
I am on Warfarin blood thinner for 3 clots in one lung, I eat a average of 3 times the amount of vitamin K needed. If I ate less I would not be healthy. My I.N.R. is 2.2. I want to get it to 2.5-3.5 the healthy number for people on blood thinners. I get tested 2 times per. week. I track vitamin K on self
m It lists vitamin K and Potassium separately, vitamin K 1 is Potassium, vitamin k is also referred to vitamin k 2. They are not the same and Spark tracks them together, that is why it is not correct for people that need to know the amount. You can look up a list of foods with any vitamin you want, it has a complete list of all 20 proteins, all 9 omegas and you can look up foods by the % of carbs, fat and protein you want combined, to get the exact amount at every meal. I will be on a precise diet for the rest of my life, also intolerant to gluten, eggs, most dairy and high acid foods and have minor kidney disease. My diet is complicated now. Report
I know I'm not getting half the vitamins I need by nutrition so I do an oral vitamin. Report
Funny how people differ. My mom has too much vitamin K. I have to bring her to Quest every couple of weeks to have her blood checked out. Her blood is thick with the stuff so we have to keep tabs on it. Report
I was looking for vitamin K- not in the article, but it comes up at the second "resource" on Spark search for vitamin K. I haven't found anything yet on spark about vitamin K. Report
Just as one example of a recent well-documented medical report on vitamin D, check out http://www.grassr
t/garland02-11. This report established no negative side effects for 40,000 IU daily (an amount much higher than I would take). The article argues for new recommendations for vitamin D recommendations. Many doctors are arguing for 8000 IU daily as the recommended dose but this article gives good evidence that 14,000 IU may be better to reach the appropriate serum 25 D levels for 97.5% of the US population. It remains to be seen how long it will take for this kind of information to become more commonly known among the general M.D. population who don't have nearly enough time to read and keep up on research. Report
This article was a bit of disappointment to me because it uses old and outdated information on dosages. For instance, there has NEVER been a documented case of vitamin D overdose. Women taking 60,000 IU daily intravenously for breast cancer treatments have experienced some nausea. (Vitamin D causes apoptosis -- the death of cancer cells.) Moreover, the article makes no mention of the fact that Vitamin D is not a vitamin but actually is a hormone. Medical doctors at grassrootshealth.
net have documented no side effects at 10,000 IU / day. They currently recommend at least 8,000 IU / day for adults.

With regard to vitamin C, many doctors recommend a dose of 3000 mg / day during flu season as an effective prophylactic. 1000 mg / day is a common dose with little danger of side effects. Because vitamin C is water soluble, your body excretes what it does not use. Those who take vitamin C regularly need to be aware that their body can "adjust" to the dosage. This can result in temporary adverse effects when they quit taking it (such as bleeding gums, easier bruising, etc.). (Vitamin C improves capillary integrity.) The best vitamin C comes with 10% of the dosage in citrus bioflavonoids. One word of caution to pregnant women: citrus bioflavonoids toughen the structure of the amniotic sack which can make it more difficult for your water to break during labor.

The article is right to warn of the danger of Vitamin A megadoses and the cautions about vitamin B for pregnant and nursing women. I do, however, wish it would break down the B vitamins a bit more. For instance, folic acid (no more than 800 mcg / day) helps to reduce inflammation in the body.

Many of the potential dangers of water-solube vitamins are mitigated by simply drinking plenty of water. Fat-soluble vitamins (such as A) need more caution regarding their use.

I understand that articles like this are written to old published standards mainly out of a sense of legal caution. But it behooves all of us to study current medical (e.g. coming from a group of... Report
Helpful article. Would like a more comprehensive article that includes more vitamins, but I guess SP needs to keep them at a certain length, or people might not read the whole thing. Report
Helpful and informative. I stick with a multivitamin that I had checked by my doctor to make sure it's ok with my prescription drugs, but it's still good to know what vitamins do. Report

About The Author

Zach Van Hart
Zach Van Hart
Zach is a journalist who regularly covers health and exercise topics.
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