Molybdenum
What is it?
Molybdenum has been considered an essential trace mineral since the 1950s. The average adult body contains about 9 mg with the highest concentrations in the liver, kidneys, bone and skin.
What it does in the body
Molybdenum is a component of the enzymes, xanthine oxidase, sulfite oxidase and aldehyde oxidase. These enzymes perform many vital functions including the production of uric acid, a nitrogen waste product of protein metabolism; carbohydrate metabolism; iron utilization; and alcohol and sulfite detoxification. They may also act as antioxidants and may play a role in normal sexual function in men.
Absorption and metabolism
Between 25 and 80 per cent of dietary intake is absorbed and excretion is mainly in the urine. Molybdenum is conserved at low intakes and excess molybdenum is rapidly excreted in the urine when intake is high.1
Deficiencies
Molybdenum deficiency is extremely rare and has only been seen in people who are on long-term tube or intravenous feeding or who have molybdenum co-factor deficiency, a rare genetic inability to use molybdenum. Symptoms of deficiency include rapid heartbeat and breathing, headache, night blindness, anemia, mental disturbance, nausea and vomiting.2 There may also be problems with sexual function and dental caries. Low molybdenum levels may be linked to an increased allergic reaction to sulfite food additives.
Marginal molybdenum deficiency has been associated with the development of cancer. In China and Japan, people living in areas where the soil is molybdenum-deficient have been found to have an increased risk of stomach and esophageal cancers.3 This may be because molybdenum-deficient plants are unable to metabolize carcinogenic compounds known as nitrosamines which are thus present in high levels in food.
Sources
Good sources of molybdenum include milk, beans, bread, liver and cereals. The molybdenum content of plants depends on the soil in which they are grown. The table below can be used as a guide.
| Food | Amount | Molybdenum (mcg) |
|---|---|---|
| Lima beans | 100g | 870 |
| Small white beans | 100g | 450 |
| Yellow split peas | 100g | 250 |
| Oats | 100g | 180 |
| Green peas | 100g | 130 |
| Chili beans | 100g | 110 |
| Raisin bran | 100g | 76 |
| String beans | 100g | 60 |
| Spaghetti | 100g | 41 |
| Macaroni | 100g | 38 |
| Rice | 100g | 29 |
| Bakery sweets | 100g | 27 |
| Bread | 100g | 21 |
| Cheese | 100g | 11 |
| Pineapple | 100g | 9 |
| Eggs | 100g | 9 |
| Banana | 100g | 8 |
| Corn | 100g | 8 |
| Spinach | 100g | 7 |
| Potatoes | 100g | 7 |
| Cabbage | 100g | 6 |
| Chicken | 100g | 5 |
| Milk | 100g | 5 |
| Bean sprouts | 100g | 5 |
Recommended dietary allowances (RDA)
There is no RDA for molybdenum. The estimated safe and adequate intake is 75 to 250 mcg per day. Average daily intake in the USA ranges from 50 to 500 mcg per day.
Supplements
Molybdenum is available commercially as sodium molybdate. The maximum daily dose should not exceed 500 mg per day. If you take molybdenum supplements, it is advisable to take 2 to 3 mg of copper to offset the risk of copper deficiency.
Toxic effects of excess intake
Toxic effects of excess molybdenum intake include weight loss, slow growth, anemia, diarrhea, increased blood levels of uric acid and swelling in the joints. This may occur at intakes of 10 to 15 mg.
Therapeutic uses of supplements
Molybdenum has been used to treat copper toxicity in cases such as Wilson's disease where levels are too high.4 Molybdenum has been used with fluoride to treat dental decay.
Interactions
The molybdenum-containing enzyme, xanthine oxidase, may help to mobilize iron from liver reserves. Molybdenum competes with copper at absorption sites, and amounts of 500 mcg per day have been found to cause significant losses of copper.