Really? Anahad O’Connor tackles health myths.

THE FACTS

Researchers used to think that children who started eating fish at an early age were more likely to develop allergies.

But lately, the tide has turned. Now scientists suspect that introducing fish at an early age may help protect against allergies. Some even argue that the rising prevalence of allergic diseases may have something to do with a corresponding drop in our consumption of immune-strengthening omega-3 fatty acids.

Theories abound, and no one knows for certain. But a number of recent studies show an association between earlier fish intake, starting around age 1, and a lower incidence of allergic diseases.

Among them was a study last year in the journal Pediatrics, which found a lower prevalence of asthma-like symptoms among children introduced to fish between 6 and 12 months.

Another study in The American Journal of Clinical Nutrition this month followed 3,300 children from their first birthdays until they turned 12. Tests showed that those whose diets included at least two servings of fish monthly were about 75 percent less likely to have allergy symptoms.

Though several other studies have yielded similar findings, they have all been observational, showing only a correlation, not cause and effect. Some scientists say that early fish consumption may be associated with a lifestyle that lowers the risk of allergic disease in non-dietary ways.

Government guidelines suggest that young children can benefit from eating up to 12 ounces weekly, or roughly two meals, of low-mercury fish.

THE BOTTOM LINE

Studies show a link between early fish consumption and reduced allergies later on, but it is not clear what is behind the association.