The FDA (Food and Drug Administration) has recommended that women who are pregnant, nursing, or trying to become pregnant eat no more than one can of light tuna a week, or 1/2 can of albacore tuna a week. In some cases the recommendation is to avoid albacore and eat only light tuna if eating tuna at all. This recommendation comes from the fear that the high levels of mercury found in tuna may damage the developing fetus or newborn.
Mercury is a known neurotoxin. It is a heavy metal that builds up in tissue, choosing the brain as a potential refuge in the human body. Mercury toxicity is associated with dementia, poor memory, and slow learning. As well it may be connected to the development of neurological disorders such as Parkinson's, Alzheimer's Disease, and Multiple Sclerosis.
Because tuna is high up in the food chain, it bio-accumulates mercury from other smaller animals and plants in the waters of the world. Then the mercury is transfered to human tissue after being consumed. Because we live for many decades the levels of mercury in our bodies can build up to toxic levels. The FDA has stated that the average level of mercury in light tuna is only 0.12 parts per million and it is not the single consumption level that is risky, but the exposure over a long period of time.
This month the Consumer Reports magazine released results from its own independent investigation. It made the recommendation that light and albacore tuna be avoided by women who are pregnant, nursing, or desiring to become pregnant due to the high risk associated with mercury exposure.
The researchers at Consumer Reports independently tested levels of mercury in canned tuna, both albacore and light. In some samples they found levels of mercury in light tuna to be three times the amount stated to be in albacore by the FDA. These levels are dangerous if consumed by women on a weekly basis. They also found lower levels in both albacore and light tuna in various samples.
Based on their data, the exact amount of mercury in light or albacore canned tuna cannot be assumed, especially because the risks may be so great. They recommend that women in the above categories find other sources of fish and shellfish that are known not to bio-accumulate mercury and choose those to satisfy dietary requirements. Fish and shellfish that are low in mercury include cod, salmon, and shrimp.
The FDA states that the health benefits of canned light tuna outweight the risk of an occassional can with higher than normal levels of mercury.
At this point it may be up to the consumer to decide if any form of canned tuna should be avoided during pregnancy, nursing, etc. Children are also advised not to eat large amounts of canned tuna on a weekly basis. The recommendation is usually 1/8-1/2 the adult serving depending on age and weight of the child.
Posted by Dr. Christina Gutierrez on June 20, 2006 03:42 PM
