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Below is a list of frequently asked questions about vitamins and nutrition.
1. What are vitamins?
Vitamins are naturally occurring compounds present in most foods. The human body cannot produce vitamins and therefore has to acquire them from external sources: diet or supplements. They are essential for all body functions including growth, repair of tissues, and the maintenance of health.
2. Where does the word "vitamin" come from?
A Polish scientist, Casimir Funk (1884-1967), coined the term "vitamin" after he discovered that certain ingredients in food are essential for maintaining health. The word "vitamin" comes from the Latin word vita (life) and the biochemical term amine (nitrogen-containing)—although we now know that not all vitamins contain nitrogen.
3. Why are vitamins important?
Our bodies use vitamins every day during the normal biochemical processes that maintain life. Vitamins help release energy from our food, and support growth, healing, and repair. An ongoing shortage of vitamins will lead to failed health, weakness, susceptibility to disease, and may ultimately result in death.
4. How many vitamins are there?
Thirteen vitamins have been identified: A, C, D, E, K, and eight in the B group. The "B complex" vitamins are thiamin (B1), riboflavin (B2), pantothenic acid (B5), pyridoxine (B6), cyanocobalamin (B12), niacin (B3), folic acid (folacin, folate) and biotin (H).
5. What is the difference between water-soluble and fat-soluble vitamins?
Vitamins are divided into two groups: water-soluble and fat-soluble. The water-soluble vitamins (C and B-complex) dissolve in water. They are easily taken up and released by body tissues. Because the body cannot store water-soluble vitamins, a daily supply is necessary. Vitamin B12 is an exception to this rule: if intake has been adequate, the liver maintains stores for several months.
Fat-soluble vitamins (A, D, E and K) dissolve in dietary and body fat. They are absorbed from food along with the fat in the food we eat. Excess fat-soluble vitamins may be stored in the liver and body fat, so several weeks' supply may be consumed in a single dose or meal.
6. What is meant by "B-complex vitamin"?
This umbrella title covers a group of 8 vitamins: thiamin (B1), riboflavin (B2), pyridoxine (B6), cyanocobalamin (B12), niacin (B3), pantothenic acid (B5), folic acid (folate) and biotin (H). Scientists have since learned each B-vitamin has a unique function.
7. What is beta-carotene?
Beta-carotene belongs to a family of compounds called "carotenoids", which give orange and yellow fruits and vegetables their characteristic colour. This vitamin is sometimes called "provitamin A" because it can be converted to vitamin A (retinol) inside the body.
The body converts only as much of beta - carotene to vitamin A as it needs. Taking excessive amounts of beta-carotene can, however, give an orange/yellowish tint to the skin (hypercarotenosis). It is not dangerous and disappears when intake is reduced or stopped.
8. Can vitamins be made in our bodies?
In a few cases, yes. Vitamin K is produced in the necessary amount by the friendly bacteria (microflora) which live in the adult gut. Newborn infants, however, have immature guts and do not have this normal bacteria. Therefore, they require additional vitamin K until the bacteria become established.
Vitamin D and niacin can also be made in our bodies. However, neither are made in the amounts required for health. For this reason, these vitamins must be obtained from food or supplements.
9. Do vitamins give you energy?
No. Vitamins help convert food into energy which your body needs to stay warm, active, and healthy. However, well-nourished individuals cannot increase their physical capacity by simply taking extra vitamins.
10. Are vitamins fattening?
No. Vitamins have no caloric value, and are not sources of energy.
11. Why do you often find vitamins in cosmetics?
Vitamins A, E, and panthenol are important for healthy skin. Vitamin A enhances the regeneration of skin cells; vitamin E helps to protect against the negative effects of ultra-violet light, reduces redness from exposure to the elements, and retains moisture in the skin. Panthenol, a derivative of pantothenic acid, keeps the skin from drying out, reduces inflammation, and adds lustre and thickness to hair. Biotin has been shown to strengthen fingernails.
12. Can vitamins be replaced by other food components such as minerals or bioflavonoids?
No. Vitamins cannot be replaced by any other food components.
13. What is the difference between an herb and a vitamin?
Vitamins are naturally occurring compounds present in most foods, which are essential for all body functions. Herbs are also natural products consisting of plant material or plant extract. However, herbs are not essential to the human body. Vitamins have a substantial body of research exploring their function in the human body, intake requirements and safety of intake. Herbs have limited research in these areas and do not have recommended intake levels since they are not essential to human life. Vitamins have strict government regulations ensuring their quality and safety. Herbs lack any legal standards for processing, harvesting or packaging.
14. Can food supply all of your vitamin requirements?
Yes. Canada's Food Guide recommends a daily intake of:
5-10 servings of fruits and vegetables.
(1 serving = 1 medium fruit or vegetable (
5-12 servings of whole grain
(1 serving = 1 slice bread or 30g cereal)
2-4 servings of milk and milk products
(1 serving = 1 cup milk or cup yogourt or 50g cheese)
2-3 servings of protein-rich meat, fish, poultry
(1 serving = 50-100g meat, poultry, fish or 1-2 eggs or 2 tbsp peanut butter)
The USDA Food Guide Pyramid recommends the following daily intake:
Use sparingly -- Fats, oils and sweets,
2-3 servings -- Milk, Yogurt, and Cheese
(1 cup of milk or yogurt, 1.5 ounces of natural cheese, 2 ounces of processed cheese)
2-3 servings -- Meat, Poultry, Fish, Dry Beans, Eggs, and Nuts
(2-3 ounces of cooked lean meat, poultry, or fish -- .5 cup of cooked dry beans, 1 egg, or 2 tablespoons of peanut butter)
3-5 servings -- Vegetables
(1 cup of raw leafy vegetables 1/2 cup of other vegetables, cooked or chopped raw 3/4 cup of vegetable juice)
2-4 servings -- Fruit
(1 medium apple, banana, orange, etc., .5 cup of chopped, cooked, or canned fruit, .75 cup of fruit juice)
6-11 servings -- Bread, Cereal, Rice, and Pasta
(1 slice of bread, 1 ounce of ready-to-eat cereal, .5 cup of cooked cereal, rice, or pasta)
15. Is it possible to have poor vitamin status and not know it?
Yes. It is possible because poor status usually develops slowly, and in the early stages, there are no classic symptoms. The non-specific characteristics of low vitamin status include fatigue and lethargy, insomnia, irritability, loss of appetite, and poor concentration.
16. What will happen if vitamin intake is very low for a day or two?
If you normally take enough vitamins and are in good health, low vitamin intake for even a week or two would not be harmful. But if your diet is short of vitamins for an extended period, you could experience a vitamin deficiency.
17. Is it possible to be overweight and still have poor vitamin status?
Yes. It is possible to be overfed and undernourished. Foods that are high in calories are often low in vitamins.
18. What are vitamin deficiencies?
"Clinical" vitamin deficiencies result in specific diseases. For example, a lack of vitamin C eventually produces scurvy, characterized by swollen joints, bleeding gums, and aching bones. Scurvy is treatable by increasing vitamin C intake with supplements or citrus fruits. Other disease states associated with classic vitamin deficiency include beriberi (thiamin deficiency), rickets (vitamin D deficiency), pellagra (niacin deficiency), and eye lesions (vitamin A deficiency).
19. What can cause vitamin deficiencies?
Causes of vitamin deficiencies can be summarized as follows:
Cause
- Inadequate food intake
- Unbalanced food consumption.
- Increased vitamin needs due to "life cycle".
- Poor absorption and digestion
- Individuals living at or close to the "poverty" line.
- Dieters consuming less than 1,800 Calories.
- Strict vegetarians.
- People with denture problems.
- People who choose food unwisely due to ignorance, apathy or depression.
- Newborn and premature infants.
- Children and adolescents in periods of rapid growth.
- Women who plan to become pregnant
- Women who are pregnant or breastfeeding their infant.
- The elderly.
- Smokers.
- Women taking oral contraceptives or hormone replacement therapy.
- People recovering from surgery or a long illness.
20. Do fresh fruits and vegetables vary in vitamin content?
Yes. Climate, soil, crop maturity, harvesting methods, transportation, and storage all affect the vitamin content of fresh foods.
21. Does food lose some of its vitamin content when stored?
Yes. Vitamin loss depends on the type of food being stored and on the length and conditions of storage. For instance, potatoes can lose as much as one third of their vitamin C content after being stored for three months. It is best to eat the freshest foods available, and as quickly as possible after buying them.
22. Is deep freezing a good method of conserving vitamins in food?
Yes. Generally, deep freezing is a good way of preserving the vitamin content of foods. However, this is not true in the case of vitamin E, which is degraded by cold temperatures. It is also important to wrap foods well to protect against dehydration, and to freeze each food. Be sure to label foods with the date of freezing, and observe the guidelines for length of storage of particular foods. Quick thawing deep frozen food, such as in a microwave oven, can also lead to vitamin losses
23. Can vitamins be unknowingly destroyed in the preparation of food?
Yes. Vitamins are sensitive to heat, air, humidity, and light. As a result, cooking foods or even just exposing them to the kitchen environment may actually destroy vitamins. To avoid vitamin loss, do not soak or overcook your food; add as little water as possible; re-use the water in which you cooked your vegetables for soups, stews or sauces; do not keep food on a warming plate, but re-heat quickly just before eating.
24. Why do food manufacturers often add vitamins to their products?
- to replace vitamins lost during food processing or storage.
- to avoid possible widespread deficiencies in the population.
- to ensure new processed foods are nutritious, as well as attractive to consumers.
- for technological reasons.
25. What are some technological reasons for using vitamins in food processing?
Vitamin C (ascorbic acid) acts as an antioxidant in products such as cured meats, vegetable oils, margarine; it also improves bread dough.
Vitamin E works as an "antioxidant" to prevent margarines and oils from becoming rancid.
Beta-carotene produces yellow to orange colours, to enhance margarine, butter, salad dressings and beverages.
26. Why do adolescents need more vitamins than adults?
The adolescent growth spurt marks a time when the body requires both more energy (Calories) and a greater quantity of essential vitamins and minerals. However, erratic eating habits, snacking, meal-skipping, eating an excessive amount of "junk" food, unsupervised dieting, or developing an eating disorder may prevent some teens from reaching this nutritional goal.
27. Could adolescents benefit from vitamin supplements?
If an adolescent eats a balanced diet, vitamin supplements are not needed. However, if the teenager is a selective eater, diets for extended periods, is extremely active in sports, is growing rapidly then a vitamin supplement may be advisable.
28. Why do adults over 55 years of age have difficulty fulfilling their vitamin requirements?
Elderly people often have little interest in food and eat less food than they require. Some reasons for this include dental problems, lack of money, or even loneliness. The aging process may also impair the ability of the intestine to absorb vitamins. For these reasons, vitamin-enriched food or vitamin supplements are often recommended for seniors to maintain good health.
29. Do the elderly have increased vitamin D needs?
Older people often have low vitamin D levels because many avoid vitamin D-rich foods such as milk, eggs and liver and, as the body ages, the ability to produce vitamin D decreases. Because sunshine is essential to this process, elderly people who do not spend enough time in sunlight or use heavy sunscreens may have inadequate vitamin D levels. Because vitamin D is toxic in high amounts, 400 IU/day should not be exceeded.
30. Are extra vitamins needed during pregnancy or breast-feeding?
Yes. Because the baby makes extra demands on the mother's body before and after birth, pregnant and nursing women have an increased need for vitamins A, C, B1, B6, B12, and folic acid. They also need extra minerals, such as calcium, phosphorus, magnesium, iodine, zinc and iron.
31. Do vegetarians receive adequate vitamins through their diet?
Strict vegetarians—that is, those who avoid meat, milk and eggs—will experience a nutritional deficiency if vitamin B12 supplements are not supplied. Pregnant women and infants are particularly at risk. Studies of "vegan" mothers show that both mother and baby often suffer from anemia and bone marrow abnormalities if vitamin B12 has not been taken during pregnancy.
32. Does an exclusively breast-fed infant receive all the necessary nutrients?
Yes. An adequate amount of human milk from a well-nourished mother meets the recommended intakes for all nutrients at this age.
33. Is it true oral contraceptives increase a woman's vitamin needs?
Yes, if the oral contraceptive taken contains high estrogen content. It is known that estrogen in the "pill" can affect the metabolism of nutrients, particularly B6 and folic acid. If pregnancy follows quickly after discontinuing the "pill", a folic acid deficiency may develop.
34. If you are dieting to lose weight, will you still obtain all necessary vitamins?
That depends on the number of calories consumed each day. Scientists have shown that the risk of obtaining an insufficient quantity of vitamins and minerals increases when the diet is less than 1,800 calories.
35. Do you need extra vitamin C if you smoke cigarettes?
Yes. The vitamin C intake needed to maintain an adequate vitamin C status is up to 50% higher in heavy smokers (at least 20 cigarettes/day) compared with non-smokers. According to the new Dietary Reference Intakes and Canadian Guidelines, adult male non-smokers require 90 mg/day of vitamin C and female non-smokers need 75 mg/day. These new guidelines indicate that smokers require an additional 35 mg/day above the new RDA. Passive smoke has been shown to increase vitamin C requirements by about 25%.
36. Is extra vitamin E needed by those on a diet high in polyunsaturated fatty acids (PUFAs)?
Research indicates that animals need more vitamin E when they are given higher amounts of polyunsaturated fatty acids. In human diets, foods which are particularly high in PUFAs are usually enriched with vitamin E.
37. Are extra vitamins recommended in times of physical stress?
Yes. The body undergoes a variety of physical stresses at various times, such as when recovering from an acute infection, an extensive skin burn, or major surgery. In the case of a serious infection, additional vitamin C may be prescribed by a doctor. Vitamin E has been shown to reduce damage which occurs to the heart during surgery due to interrupted blood flow.
Vigorous exercise has been shown to increase the production of free radicals. There are some evidence vitamins C, E and beta-carotene may protect against such damage.
38. Are extra vitamins needed during emotional stress?
It is not known whether vitamins play a role in coping with emotional stress because little research exists in this area.
39. Does medication affect vitamin requirements?
Yes. Regular use of some medications may upset the vitamin balance by changing our ability to absorb, use, store, or excrete vitamins. Some examples are: oral contraceptives reducing folic acid and B6 levels; aspirin (ASA) and anticonvulsants affecting folic acid; neomycin and cholestryamine affecting B12; isoniazid affecting niacin; laxatives such as mineral oil impairing the status of vitamins A, E, and D. Ask your pharmacist about the potential of your medication to interact with vitamins and other nutrients if you are concerned.
40. Do vitamin supplements affect appetite?
No. Supplemental vitamins do not affect the appetite. However, vitamin deficiencies may contribute to a loss of appetite. By restoring vitamin balance, the appetite might improve.
41. There are so many multivitamin supplements on the market; what criteria should be used in making an appropriate choice?
Check the label to be sure:
- the product contains 12 vitamins and beta-carotene (in most countries vitamin K is restricted in vitamin supplements)
- the amount of each vitamin is approximately equivalent to 1-3 times the Recommended Nutrient Intake (RNI) or Dietary Reference Intakes (DRI)
- The expiry date has not passed.
42. Are vitamin supplements helpful when you feel weak and lack energy?
If your fatigue and lethargy is the result of a lack of vitamins due, for example, to poor dietary habits, a multivitamin supplement may improve your condition. See your doctor to rule out other causes of these non-specific symptoms.
43. Is the time of day that you take vitamin supplements important?
No. However, it's easier to remember to take vitamin supplements at the same time each day--at breakfast, for example. That way, taking your supplement becomes part of your routine.
You should also be aware that certain nutrients enhance the absorption of others. For example, vitamin D is essential for calcium absorption (hence vitamin D fortification of milk) and vitamin C aids iron absorption. For this reason, it is best to take an iron supplement with a source of vitamin C (fruit, fortified drink, or supplement).
44. Are slow-release or timed-release preparations superior to regular vitamin supplements?
No, but they may be preferable to use in some cases. If very high doses of a particular water-soluble vitamin are to be taken, then slow/or timed-release preparations are often preferred.
45. Are vitamin C supplements which contain bioflavonoids more easily digested?
Research suggests that vitamin C may be used more efficiently when certain bioflavonoids are present. Bioflavonoids are being investigated as a possible preventive against heart disease.
46. How should vitamin supplements be stored?
Because vitamins are vulnerable to light, air, heat, and moisture, they should be stored in a cool, dry place. Do not store vitamins in the refrigerator because they will collect moisture. Keep them out of the reach of children.
47. Can vitamin supplements deteriorate?
Yes. However, if vitamin supplements are correctly stored, they will keep for two or three years. Choose a supplement with an expiry date on the packaging, and discard the product when the expiry date has passed.
48. What other ingredients are used to prepare a vitamin tablet?
Vitamin tablets contain ingredients other than vitamins. For example, starch may be used as a binder, lactose as a stabilizer, and sugar and food colour as a coating. All ingredients in vitamin supplements must be regarded as safe. If you experience an allergic reaction to a supplement, it may be due to these "excipients" or dyes rather than to the vitamin itself.
49. Is there any difference between "natural or organic" vitamins versus synthetic?
No. Synthetic vitamins are identical in chemical structure to those found in food. A difference between natural and synthetic vitamins has not been demonstrated for any vitamins, except vitamin E. The form of vitamin E derived from "natural" products is more biologically active than its synthetic form.
50. Are chewable vitamins harmful to children's teeth?
Probably not, unless the child is taking more than the recommended amount. Most chewable children's formulations contain sugar substitutes, instead of sugar, and sodium ascorbate, the least acidic form of vitamin C.
51. Can multivitamin supplements be taken regularly over a long period?
Yes. The amounts contained in multivitamins and prenatal supplements are considered safe. However, continued use of high amounts of vitamin A or D—that is, more than 10 times the DRI or RNI for vitamin A, or 5 times the DRI or RNI for vitamin D can have a negative impact on your health.
52. Are vitamins safe if taken in large amounts?
Yes and no. Given the vast differences in individual vitamin requirements and tolerances, there is no absolute rule. As a general guide, water-soluble vitamins (vitamin C and the B complex) can be taken in amounts up to 100 times the DRI or RNI. Surplus amounts are excreted in the urine.
The fat-soluble vitamins A and D have a much lower safety margin. Vitamin A is generally considered safe in amounts up to 10 times the normal daily recommendation, and vitamin D up to 5 times the DRI or RNI recommendation. High doses of A or D should only be taken under the direction of a doctor.
53. What can happen if too much vitamin A is consumed?
"Hypervitaminosis A" (from the Greek "hyper"—too much) causes symptoms such as loss of appetite, blurred vision, headache, muscle soreness, loss of hair, redness and peeling of the skin.
54. Should vitamins be regarded as "drugs"?
In some cases, yes. Vitamin supplements taken at high dosages may produce therapeutic or drug-like effects. An example is niacin, which is sometimes prescribed in very high doses to reduce cholesterol levels in the blood. Vitamin therapy of this nature should always proceed under the supervision of a physician.
As with drugs, vitamin supplements should be used as directed and keep out of the reach of children. An accidental overdose must be brought to the attention of trained medical personnel.
55. Why does urine often turn bright yellow when vitamin B-complex or a multivitamin supplement is used?
This is caused by the riboflavin (vitamin B2), which has an intense yellow color. If you are taking more vitamins than you need, you get rid of the excess (water soluble only) through the urine. This is a natural process and no cause for alarm.
56. Can overexposure to the sun cause vitamin D toxicity?
No. There is no risk of vitamin D toxicity from prolonged sun exposure. Production of vitamin D in the skin from sunlight is automatically regulated by the body.
57. Are vitamin E supplements safe?
According to well-documented studies, adults have taken 800-900 IU daily of vitamin E for extended periods of time without any side effects. Most vitamin E supplements contain 100 to 400 IU, well below the level at which minor complaints such as stomach discomfort has been reported. People who are taking medication should check with their doctor before taking high doses of vitamin E because, in rare cases, negative drug/nutrient interactions may occur.
58. Does a high dose of vitamin C—3 grams per day, for example—cause any side effects?
Few side effects occur even with large doses of vitamin C. However, one side effect of large doses of vitamin C (ascorbic acid) is a mild laxative effect. This can often be avoided by taking vitamin C in several smaller doses over the day. As a matter of fact, the body can use four 250 mg doses of vitamin C more efficiently than one single dose of 1,000 mg.
59. Is there a danger of getting kidney stones from regular use of vitamin C supplements?
Studies have shown that there is no increased risk. However, people with a history of kidney stones should not take more than the daily recommendation (DRI) for vitamin C. Higher doses (several grams) do not pose a risk to other individuals.
60. Is there a risk of "rebound scurvy" if high doses of vitamin C supplements are abruptly stopped?
No. Many investigations have been carried out, both in humans and animals, which demonstrate that the body does not increase its requirement for vitamin C when large doses are taken. So if you take a large amount of vitamin C, and then stop abruptly, you will not be at risk for a vitamin C deficiency.
61. Should supplementary vitamin C be avoided by people who have stomach ulcers and need to avoid acidic foods?
In its usual form, yes. However, vitamin C also exists in the form of sodium or calcium ascorbate, which is non-acidic, but just as effective as ascorbic acid. A pharmacist, physician or dietitian can advise you on the preparation best suited to your needs.
62. Is it safe to take beta-carotene supplements?
Beta-carotene has a well established safety record; it has been used in many studies with no reported side effects other than yellowing of the skin. Physicians have been using beta-carotene to treat patients suffering from photosensitivity diseases without complications with doses of up to 180 mg/day.
63. Is there an advantage in consuming extra vitamin C if you have an iron deficiency?
Yes. Iron deficiency anemia results not only from an insufficient intake of iron, but also from poor absorption of iron from the diet. When foods high in vitamin C or vitamin C supplements are taken together with meals containing iron (iron from vegetable sources), the absorption of iron is dramatically improved.
64. Can vitamin B6 relieve the symptoms of premenstrual syndrome (PMS)?
Studies have shown vitamin B6 to be effective in alleviating some symptoms of "PMS" in some women, such as breast tenderness, headache, tension, irritability, and bloating. A general dosage range of 50-100 mg/day is recommended and considered safe.
65. Does vitamin E help to heal skin burns?
Yes. When applied as a liquid or ointment directly to burns or cuts, vitamin E is believed to speed healing. Although there is no conclusive scientific evidence to support this observation, experiments have confirmed that vitamin E often reduces redness and inflammation.
66. Can vitamin supplements enhance human fertility?
We don't know since research has just begun in this area. One study on male infertility found an association between a low level of vitamin C in the body and sperm "clotting", a condition that inhibits the ability of sperm to move.
67. Is vitamin C helpful in treating colds?
Studies show that 250-2,000 mg/day of vitamin C—taken as food or a food supplement (250 mg is the equivalent of 18 oz. of orange juice)—decreases the duration of colds as well as certain symptoms.
68. Is it true that vitamin E can protect our lungs from cigarette smoke and air pollution?
Yes. Experiments on animals and humans indicate that vitamin E reacts in the lungs with major toxic air pollutants such as nitrogen dioxide and ozone, guarding against their harmful effects. Vitamin E levels in humans are lowered by cigarette smoking.
69. Can the risk of cancer be reduced by taking extra vitamins?
Perhaps. Research from over 200 studies has shown a relationship between low vitamin A (and beta-carotene) intake and the occurrence of cancers of the lung and stomach. And, studies have shown vitamins C and E can prevent the formation of nitrosamines, especially in the stomach. (Nitrosamines are substances formed in the body, in foods, and in cigarette smoke which can be cancer-causing.)
70. Can vitamin D help prevent osteoporosis?
Not directly. Vitamin D does, however promote the absorption of dietary calcium and the mineralization of bones. When vitamin D is absent, these processes are impaired. Serious deficiency diseases may result, such as rickets in children and the softening of the bones in adults.
Inadequate vitamin D and calcium intakes may contribute to the development of osteoporosis. Vitamin D is a fat-soluble vitamin and therefore can be toxic in large amounts. The upper daily limit for adults is 50 mcg or 2,000 IU.
71. Do vitamins strengthen the immune system?
Yes. Good nutritional status is an important defense against illness. Vitamins A, C, E, B6 and beta-carotene, have been shown to be essential to maintaining the immune system.
72. Can vitamins play a role in the fight against AIDS?
Yes. Because malnutrition often results from AIDS, vitamin supplements help patients meet nutrient requirements when nausea, diarrhea and poor digestion affect food intake. In addition, good vitamin status enhances the body's immune system and has been shown to delay the onset of AIDS in HIV positive individuals.
73. Can supplements help the management of diabetes?
Some studies have shown B6 supplementation reduces the painful neuropathy experienced by some diabetics. Vitamin E has been shown to improve natural insulin action in non-insulin dependent diabetics by increasing glucose metabolism. Vitamin E may also provide protection against oxidative damage, which occurs more frequently in diabetics, due to their high rate of lipolysis in their metabolism. Studies have also shown diabetics have lower levels of vitamin C blood levels than non-diabetics, even when both groups consumed the same amounts of vitamin C.
74. One hears more and more about the role of vitamins neutralizing "free radicals" in the body. What does that mean?
Free radicals are highly reactive compounds produced spontaneously in the body or because of exposure to certain pollutants. They can be dangerous, since they cause damage to body cells and tissues, including genetic material. Recent studies indicate that vitamins C, E, and beta-carotene protect against free radical damage.
75. Do vitamins help prevent heart attacks?
There is a strong association between vitamin intake and incidence of heart attack. Various studies have recently established that people with low levels of vitamins A, E, C, and beta-carotene are more likely to develop heart disease. Recently, one large scale study conducted with 87,000 nurses and another with nearly 40,000 male health professionals found that those who took 100—200 IU of vitamin E daily for at least two years had a lower incidence of cardiovascular disease than the control groups (for women, a 34% reduction in risk and for men a 40% reduction). In another study, male physicians who took beta-carotene supplements had a significantly lower incidence of cardiovascular illness than those who took no supplements. However, more research is needed to explain the role of vitamins in the area of cardiovascular disease.
Frequently Asked Questions (FAQ)
1- What is a dietary supplement ?
A dietary supplement is a product taken by mouth that contains a "dietary ingredient": vitamins, minerals, herbs, amino acids, enzymes, organ tissues, glandular, and metabolites. Dietary supplements can also be extracts or concentrates, and may be found in many forms such as tablets, capsules, soft gels, liquids, or powders.
2- How do I know if I need a dietary supplement?
It is important to remember that supplements include vitamins and minerals, as well as herbs, botanicals and other substances. Dietary supplements are not intended to treat, diagnose, mitigate, prevent, or cure disease. Do not self diagnose any health condition. Work with your health care provider before taking a supplement.
3- How can I get more information about a particular dietary supplement such as whether it is safe and effective?
Research studies in people to prove that a dietary supplement is safe are not required before the supplement is marketed, unlike for drugs. The manufacturer does not have to prove that the supplement is effective, unlike for drugs. The manufacturer can say that the product addresses a nutrient deficiency, supports health, or reduces the risk of developing a health problem. . It is important to ensure that you obtain information from reliable sources such as:
• Fact sheets on dietary supplements from the National Institutes of Health
• Nutrient Recommendations: Dietary Reference Intakes (DRI) and Recommended Dietary Allowances (RDA)
• PubMed Dietary Supplement Subset
• Dietary supplement warnings and safety information from the U.S. Food and Drug Administration
• Consumer information from the Federal Trade Commission
4- Where can I find information about the use of dietary supplements for a particular health condition or disease?
Whatever your choice, supplements should not replace prescribed medications. It is important to ensure that you obtain information from reliable sources such as:
• Health Information from the National Library of Medicine's MedlinePlus Database
• Fact sheets on dietary supplements from the National Institutes of Health
• PubMed Dietary Supplement Subset
5- What is the difference between the RDA and DV for a vitamin or mineral?
Many terms are used when referring to either the amount of a particular nutrient you should get or the amount in a food or dietary supplement. The two most common are the Recommended Dietary Allowance (RDA) and the Daily Value (DV). These terms can be confusing. RDAs are recommended daily intakes of a nutrient for healthy people. They tell you how much of that nutrient you should get on average each day. They vary by age, gender and whether a woman is pregnant or breastfeeding; so there are many different RDAs for each nutrient. For each nutrient, there is one DV for all people ages 4 years and older. Therefore, DVs aren't recommended intakes, but suggest how much of a nutrient a serving of the food or supplement provides in the context of a total daily diet. DVs often match or exceed the RDAs for most people, but not in all cases.
DVs are presented on food and supplement labels as a percentage. They help you compare one product with another. As an example, the %DV for calcium on a food label might say 20%. This means it has 200 mg (milligrams) of calcium in one serving because the DV for calcium is 1,000 mg/day.
6- Where can I get advice about complications caused by a particular dietary supplement?
Usually each brochure supplement have noted about its side effects. Advice your dietician, physician or pharmacist if you require more information.
7- Where can I purchase dietary supplements?
Dietary supplements are available without a prescription through a number of retail outlets including grocery stores, drug stores, natural food stores and specialty health and nutrition stores. Many dietary supplements can also be purchased online through the Internet.
8- Which brand(s) of dietary supplements should I purchase?
There are a number of factors including price, quality and availability that may influence your buying decision. You may wish to ask your health care provider to make a recommendation.
9- How do I know if the supplement that I purchased contains the ingredients that it claims on the label or if it is contaminated?
Manufacturers are expected to guarantee the identity, purity, strength, and composition of their dietary supplements. Some manufacturers use the term "standardized" to describe efforts to make their products consistent. However, law does not define standardization.
10- Who is responsible for overseeing the regulation of dietary supplements in Iran? Food and drug organization