Deficiencies and toxicity




See Vitamin, Mineral (nutrient), Protein (nutrient)

An inadequate amount of a nutrient is a deficiency. Deficiencies can be due to a number of causes including an inadequacy in nutrient intake, called a dietary deficiency, or any of several conditions that interfere with the utilization of a nutrient within an organism. Some of the conditions that can interfere with nutrient utilization include problems with nutrient absorption, substances that cause a greater than normal need for a nutrient, conditions that cause nutrient destruction, and conditions that cause greater nutrient excretion. Nutrient toxicity occurs when excess consumption of a nutrient does harm to an organism.

In the United States and Canada, recommended dietary intake levels of essential nutrients are based on the minimum level that "will maintain a defined level of nutriture in an individual", a definition somewhat different from that used by the World Health Organization and Food and Agriculture Organization of a "basal requirement to indicate the level of intake needed to prevent pathologically relevant and clinically detectable signs of a dietary inadequacy".

In setting human nutrient guidelines, government organizations do not necessarily agree on amounts needed to avoid deficiency or maximum amounts to avoid the risk of toxicity. For example, for vitamin C, recommended intakes range from 40 mg/day in India to 155 mg/day for the European Union. The table below shows U.S. Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for vitamins and minerals, PRIs for the European Union (same concept as RDAs), followed by what three government organizations deem to be the safe upper intake. RDAs are set higher than EARs to cover people with higher than average needs. Adequate Intakes (AIs) are set when there is not sufficient information to establish EARs and RDAs. Governments are slow to revise information of this nature. For the U.S. values, with the exception of calcium and vitamin D, all of the data date from 1997–2004.

Nutrient U.S. EAR Highest U.S.
RDA or AI		 Highest EU
PRI or AI		 Upper limit Unit
U.S. EU Japan
Vitamin A 625 900 1300 3000 3000 2700 µg
Vitamin C 75 90 155 2000 ND ND mg
Vitamin D 10 15 15 100 100 100 µg
Vitamin K NE 120 70 ND ND ND µg
α-tocopherol (Vit E) 12 15 13 1000 300 650-900 mg
Thiamin (Vit B1) 1.0 1.2 0.1 mg/MJ ND ND ND mg
Riboflavin (Vit B2) 1.1 1.3 2.0 ND ND ND mg
Niacin* (Vit B3) 12 16 1.6 mg/MJ 35 10 60-85 mg
Pantothenic acid (Vit B5) NE 5 7 ND ND ND mg
Vitamin B6 1.1 1.3 1.8 100 25 40-60 mg
Biotin (Vit B7) NE 30 45 ND ND ND µg
Folate (Vit B9) 320 400 600 1000 1000 900-1000 µg
Cobalamin (Vit B12) 2.0 2.4 5.0 ND ND ND µg
Choline NE 550 520 3500 ND ND mg
Calcium 800 1000 1000 2500 2500 2500 mg
Chloride NE 2300 NE 3600 ND ND mg
Chromium NE 35 NE ND ND ND µg
Copper 700 900 1600 10000 5000 10000 µg
Fluoride NE 4 3.4 10 7 ____ mg
Iodine 95 150 200 1100 600 3000 µg
Iron 6 18 (females)
8 (males)		 16 (females)
11 (males)		 45 ND 40-45 mg
Magnesium* 350 420 350 350 250 350 mg
Manganese NE 2.3 3.0 11 ND 11 mg
Molybdenum 34 45 65 2000 600 450-550 µg
Phosphorus 580 700 640 4000 ND 3000 mg
Potassium NE 4700 4000 ND ND 2700-3000 mg
Selenium 45 55 70 400 300 330-460 µg
Sodium NE 1500 NE 2300 ND 3000-3600 mg
Zinc 9.4 11 16.3 40 25 35-45 mg
  • For niacin and magnesium there appears to be a contradiction inherent in the information in the table, as the amounts recommended for daily consumption can be more than the amounts identified as the safe upper limits. For both nutrients, the ULs identify the amounts which will not increase risk of adverse effects when the nutrients are consumed as a serving of a dietary supplement. Magnesium above the UL may cause diarrhea. Niacin above the UL may cause flushing of the face and a sensation of body warmth. Each country or regional regulatory agency decides on a safety margin below when symptoms may occur, so the ULs can differ.

EAR U.S. Estimated Average Requirements.

RDA U.S. Recommended Dietary Allowances; higher for adults than for children, and may be even higher for women who are pregnant or lactating.

AI U.S. Adequate Intake; AIs established when there is not sufficient information to set EARs and RDAs.

PRI Population Reference Intake is European Union equivalent of RDA; higher for adults than for children, and may be even higher for women who are pregnant or lactating. For Thiamin and Niacin, the PRIs are expressed as amounts per megajoule (239 kilocalories) of food energy consumed.

Upper Limit Tolerable upper intake levels.

ND ULs have not been determined.

NE EARs, PRIs or AIs have not yet been established or will not be (EU does not consider chromium an essential nutrient).

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