Vitamins and minerals are necessary for all body functions. Vitamins are categorized as fat-soluble and water-soluble. Minerals are classified as macrominerals, meaning they are required in quantities over 100 mg per day, and trace minerals, requiring less than 100 mg per day. Safe levels of each nutrient have been established in the Dietary Reference Intakes, or DRIs, which include the recommended daily allowance, or RDA, the adequate intake, or AI, and tolerable upper limit, or UL. While the body requires vitamins and minerals, too much can be toxic.
Fat-Soluble Vitamins
The fat-soluble vitamins that have known toxic levels are A and D.
The RDA for vitamin A is 800 micrograms for women and 100 micrograms for men. Excessive levels of vitamin A can result in joint pain, thickening of long bones, loss of hair and jaundice. Toxic levels of vitamin A can damage the liver in two ways: portal hypertension, which is high blood pressure in the flow of blood from the intestines to the liver, and ascites, a term for fluid in abdominal cavity.
The RDA for vitamin D for both men and women age 0 to 50 is 5 micrograms per day, with UL intake of 50 micrograms per day. Toxic levels of vitamin D can result in calcification of kidneys and lungs. It can also cause high levels of calcium in the blood in infants and calcium deposits on the kidneys in infants and adults. This interferes with the functioning of the kidneys.
Water-Soluble Vitamins
The water-soluble vitamins with toxic levels are the B vitamins niacin, B-6, folate and choline.
The RDA for niacin for men age 14 and older is 16 mg niacin equivalent, or NE, per day and 14 mg NE per day for women. Excess niacin intake from nonprescription medication can result in a reddened flush of the face, arms and chest that is concurrent with burning, tingling, and itching. There are no adverse reactions from excess dietary niacin.
The RDA for vitamin B-6 for both men and women up to age 50 is 1.3 mg per day. Like niacin, there are no adverse effects from high B-6 intake from food. Excess B-6 intake from supplements can cause lack of muscular coordination and nerve damage.
The RDA for folate in both men and women over the age of 14 is 400 micrograms per day. The UL of dietary folate equivalent, or DFE, is 1,000 micrograms per day. There have been no adverse effects with excessive dietary consumption of folate. Excess folate supplementation can result in insomnia, physical discomfort, irritablility and intestinal discomfort.
The AI levels of choline are 550 mg per day for men over the age of 14, and 425 mg per day for women over the age of 18. In women, pregnancy and lactation increase the AI. Toxic levels of choline result in lowered blood pressure, fishy body odor, excessive perspiration, salivation and reduced growth rate.
Macrominerals
The macrominerals with toxic levels are calcium, phosphorus and magnesium.
The RDA for calcium varies and increases by age. For both men and women age 19 to 50, the AI is 1,000 mg per day and 1,200 mg per day over the age of 50. The UL for both men and women over the age of 1 is 2,500 mg per day. Calcium intake above the UL can result in calcification of soft tissue and increases the risk of calcium-containing kidney stones.
The RDA for phosphorus increases with age from birth to 18. The RDA for both men and women over the age of 19 is 700 mg per day. Pregnancy and lactation increase these amounts. The UL for ages 9 to 70 is 4,000 mg per day. Toxic levels of phosphorus are rare but can cause calcification of the soft tissues.
The RDA for magnesium is 400 mg per day for men and 310 mg per day for women ages 19 to 30, and 420 mg per day for men and 320 mg per day for women 31 and older. Excessive magnesium intake is not likely except in those with impaired kidney function, but it can cause diarrhea, dehydration, nausea, flushing, impaired vision, slurred speech and weakness.
Microminerals
The microminerals with toxic levels are iron, zinc, copper, selenium, manganese and fluoride.
The RDA for men and postmenopausal women is 10 mg per day, 15 mg per day for premenopausal women, and 30 mg per day for pregnant women. Toxic levels of iron causes hemochromotosis, a condition that causes tissue damage to the liver and heart.
The RDA for zinc is 15 mg per day for men and 12 mg per day for women. Toxic levels of zinc cause nausea, vomiting, epigastric pain, abdominal cramps, bloody diarrhea and a metallic taste in the mouth.
The RDA for copper is 1.5 to 3 mg per day for both children and adults. Copper toxicity is rare, but poisonings have occurred with water contamination and accidental ingestion. Symptoms of toxicity are nausea, diarrhea, vomiting, jaundice, blood in urine and reduction of urine output.
The RDA for selenium is 70 micrograms per day for adult men and 55 micrograms per day for adult women. Toxic levels cause nausea, vomiting, fatigue, hair loss, nail loss and interference in sulfur and protein metabolism.
The estimated safe and AI level for manganese is 2 to 5 mg per day. Toxicity symptoms can occur in individuals with existing terminal conditions such as liver failure and those exposed to elevated airborne manganese concentrations.
The AI for fluoride is 3.8 mg per day for men and 3.1 mg per day for women. Fluoride toxicity is referred to as fluorosis and is characterized by changes in bone, kidney, nerve and muscle function. Acute toxicity presents as nausea, vomiting, acidosis, cardiac arrythmias, and in rare instances, death.
Considerations
Vitamins and minerals are necessary for the proper functioning of all body systems. However, too much of a good thing can be harmful. Consult your physician for advice on taking any dietary supplements.
References
- "Basic Nutrition and Diet Therapy": Sue Rodwell Williams: c. 2001
- "Advanced Nutrition and Diet Therapy, Third Edition": James L. Groff, Sareen S. Gropper: c. 2000
- Linnus Pauling Institute at Oregon State: RDA for phosphorus
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