Progresso, which is owned by General Mills, said that it has made the announcement now in response to current competitive advertising in the category, particularly from Campbell Soup.
Kyle Duea, marketing manager for Progresso, said 26 of its soups are already MSG free and the company would have preferred to announce the change when they had implemented this strategy across the Progresso line.
However, the company said that in recent advertising for Select Harvest soup, Campbell referred to MSG, making “unflattering comparisons” to Progresso soups that have not been reformulated.
Duea said Progresso expects its strategy to put pressure on Campbell.
The additive MSG is mainly used as a flavor enhancer for foods such as soups, ready meals, fish and meat dishes.
However, ingredients companies have been developing alternatives to MSG as it has fallen out of favor among manufacturers and consumers following health concerns.
The publication BrandWeek reported last month that Campbell had launched an ad taking direct aim at its rival. The advert in the New York Times showed a can of Progresso with the caption "Made With MSG". It ran alongside an image of Campbell's Select Harvest soup with caption "Made With TLC", or "tender love and care".
In September Campbell Soup launched its Select Harvest soups range to appeal to more label-conscious consumers by spelling out on tin exactly what has gone into it and ingredients that have been avoided.
The ingredients it avoided included MSG, high fructose corn syrup, artificial flavors and hydrogenated oils. The packaging affected the 44 new soups.
However, Campbell highlighted that some of the soups contained yeast extract, a natural ingredient that contains a small amount of naturally occurring monosodium glutamate. Naturally occurring glutamate is also found in foods like mushrooms, cheese and tomatoes.
In 1959, the US Food and Drug Administration classified MSG as a "generally recognized as safe".
Since then some academics have warned of health risks from consuming MSG. In 1992, the FDA asked an independent group of scientists - The Federation of American Societies for Experimental Biology (FASEB) - to complete a review of available scientific data on glutamate safety.
The report reaffirmed the safety of MSG when consumed at usual levels. A large dose would be three grams or more per meal. A typical serving of glutamate-treated food contains less than 0.5 grams of MSG.
However it did identify short-term reactions known as MSG Symptom Complex, which people can experience after eating large doses of MSG, particularly on an empty stomach, as well as those with severe and poorly controlled asthma.
Symptoms include numbness, burning sensation, tingling, facial pressure or tightness, chest pain, headache, nausea, rapid heartbeat, and drowsiness.