- Ask a Doctor before Taking Vitamins and Minerals - Gaston Thauvin
Vitamins and minerals are essential nutrients that keep the body healthy and functioning properly. When absorbed in the body through food, or taken in moderate doses through supplement form, vitamins and minerals are beneficial to a person’s health. However, when taken in excess of the recommend dose, many can become dangerous. Here is a list of vitamins and minerals that can become toxic in large doses.
Vitamins
Vitamin A – Vitamin A should not be taken in doses over 10,000 IU (International Units) per day by adults and children unless advised by a doctor. Pregnant women should avoid taking large doses of vitamin A because of the risk of birth defects occurring with the baby. The average adult age 19 and older requires between 700 to 900 IU of vitamin A each day. Symptoms of Vitamin A toxicity are headaches, nausea, diarrhea, dry skin and hair loss.
Vitamin B – The B vitamins are water soluble and do not store in the body and become toxic like some vitamins can. However, taking too much vitamin B can cause a person to urinate too much and cause imbalances in other nutrients. Doses of niacin (vitamin B3) of over three grams per day can cause liver damage, abnormal glucose tolerance, gout and gastric ulceration. Doses of over 300 milligrams (mg) per day of vitamin B6 (pyridoxine) can lead to problems with the nervous system.
Vitamin C – Vitamin C is also water soluble and does not store in the body. However, consistently taking doses of vitamin C over three grams each day can lead to kidney stones, urinary tract irritation, nausea, diarrhea and blood clots. The average adult age 19 and over should have 75 to 90 mg per day of vitamin C through diet or supplement form.
Vitamin D – The recommended dietary allowance (RDA) of vitamin D varies depending upon age, darkness of skin and how much sun exposure the person has. On the average, an adult needs 400 IU each day. Taking 10,000 IU or more each day can lead to calcium deposits all over the body, kidney stones, high blood pressure and high cholesterol. In infants and children, overdoses of vitamin D can lead to diarrhea, nausea, frequent urination, loss of appetite, dizziness, weakness, calcium deposits in kidneys and excessive calcium in the blood. It is best for children to not take vitamin D supplements (unless prescribed by a doctor) and get all of their D through fortified milk, yogurt and sunshine.
Vitamin E – Taken in small doses, vitamin E is a safe and full of healthy antioxidant properties. However, vitamin E can become dangerous if taken in doses of 1,000 IU or more each day. The RDA for the average adult age 14 and up is 15 mg or 22.4 IU. Symptoms of overuse of vitamin E are fatigue, increased hypertension, slowed immune system and excessive bleeding due to vitamin E being an anticoagulant. Most people can absorb enough vitamin E through diet and should not take supplements unless prescribed by a doctor.
Minerals
Calcium – The RDA of calcium varies depending upon age but the average adult age 19 to 60 years old needs between 1,000 and 1,200 mg each day. If more than 2,000 mg is taken daily, calcium can become dangerous. Symptoms of calcium overdose include extreme lethargy, calcium deposits in tissues throughout the body, impaired absorption of zinc, iron and magnesium and impaired kidney function.
Iodine – The RDA for iodine is 150 mcg (micrograms), which is ½ teaspoon per day. While iodine is necessary for a healthy thyroid gland, when taken in large doses of two milligrams or more per day it can shut down the thyroid gland. Other symptoms of iodine overload are weight gain, metallic taste in mouth, dry skin and hair, rash, constipation, diarrhea, vomiting, mouth sores, swollen salivary glands, headache, breathing difficulties and excessive menstrual bleeding.
Iron – Iron is an important mineral but too much iron can cause dangerous side-effects. The RDA of iron varies depending upon age and is as follows:
- age 14 to 18: up to 15 mg/day
- age 19 to 50: 8 mg/day for males and 18 mg/day for females
- age 51+: 8 mg/day for both males and females
Excesses of 25 mg/day of iron can lead to headache, constipation, weight loss, fatigue, zinc and copper deficiencies and damage to the heart, liver and pancreas. Iron supplements should not be taken unless prescribed by a doctor.
Selenium – The RDA for selenium is 40 mcg/day for children age nine to 13 and 55 mcg/day for age 14+. When taken in excess of 750 mcg/day, selenium can cause hair and nail loss, low immune system, tooth decay, paleness, weakness, yellowish skin, skin lesions, low energy levels and diabetes.
Zinc – Zinc should never be taken in excess of 75 mg per day unless advised by a doctor. The RDA for zinc for adults is 11 mg for males and 8 mg for females. Excessive amounts of zinc can cause vomiting, nausea, changes in HDL/LDL cholesterol levels, low immune system, anemia, abdominal pain and bleeding in the stomach. Too much zinc in pregnant women can cause stillbirth and premature birth.
It is always best to get vitamins and minerals through a balanced, healthy diet. Supplements should only be taken if advised by a doctor. There really is truth to the saying “too much of a good thing.” Eat healthy and avoid taking high quantities of any vitamins and minerals.
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Deanna Lynn Sletten - Deanna Lynn Sletten has been a freelance writer for newspapers, regional magazines and websites for 20 years. She specializes in the ...
