Owing to intense competition from China, manufacturing artificial sugar substitutes is not the sweet business it once was. Aspartame maker NutraSweet says it will shutter its plant in Georgia, and sucralose maker Tate & Lyle is warning investors of significant profit erosion.

By the end of the year, NutraSweet will close the plant in Augusta, Ga., which produces bulk aspartame and the precursor l-phenylalanine. About 210 people will lose their jobs.

“Low-cost imports now dominate the aspartame market, making it impossible to sustain a profitable business,” says William L. DeFer, CEO of the privately held NutraSweet. The firm will continue to make the artificial sweeteners neotame and Twinsweet, a mixture of aspartame and acesulfame potassium.

“Aspartame is a great product, but the competition, especially from China, is brutal,” says Grant E. DuBois, who once worked for NutraSweet and now has his own consulting firm, Sweetness Technologies. The shutdown will leave China’s Niutang as the dominant low-cost producer of both aspartame and sucralose.

Only one other major company besides Niutang, Japan’s Ajinomoto, will be left making aspartame, DuBois notes, and Ajinomoto’s aspartame business is also in distress. The firm recently told investors that global overcapacity and low Chinese prices were hurting profits. Ajinomoto is seeking a buyer for its aspartame plant in France, a move that would leave it with one plant in Japan.

NutraSweet traces its roots back to pharmaceutical firm G.D. Searle, which invented aspartame in 1965 and brought it to market in 1981. Monsanto bought Searle in 1985 and sold NutraSweet to the private equity firm J.W. Childs in 2000.

Aspartame lost patent protection in 1992, and NutraSweet has faced growing competition ever since. The story is similar for the artificial sweetener sucralose, whose original maker, Tate & Lyle, lost patent protection in 2009.

In a call last month with investors, Tate & Lyle CEO Javed Ahmed blamed “irrational behavior by some market participants,” referring to Chinese firms, for erosion in the price of the firm’s Splenda brand sucralose. Ahmed offered no immediate remedy other than to say that the British firm would not compete for “certain volumes where we do not see value.”