Excessive amounts of vitamins and minerals in certain foods may be harmful to consumers, particularly young children, pregnant women, and senior citizens, according to new research. A recent report from the Environmental Working Group offers additional details.

The report studied cereals and snack bars, some of the most commonly fortified food categories. Evidence showed that more than 140 of them are fortified to the point of potentially harming consumers.

Specific vitamins and minerals included vitamin A, zinc, and niacin.

The reasoning behind the fortification, according to the EWG, is flawed government policies and food producers who enhanced foods with various nutrients in an effort to build up sales. The result is that a large number of consumers, particularly children, are consuming large amounts of certain nutrients.

Renee Sharp, EWG’s research director and the report’s co-author, said in a statement, “Heavily fortified foods may sound like a good thing, but when it comes to children and pregnant women, excessive exposure to high nutrient levels could actually cause short or long-term health problems.” Sharp continued, “Manufacturers use vitamin and mineral fortification to sell their products, adding amounts in excess of what people need and more than might be prudent for young children to consume.”