The most common claims made on the company's websites are that cherries contain potent anticancer agents, can relieve pain of gout or arthritis, and are beneficial for heart health.
In fact, a number of studies exist that point to the health benefits of cherries. These include the work of Russel Reiter and colleagues at the University of Texas Health Center, who detected high levels of the anti-oxidant melatonin, understood to function as a free-radical scavenger, in tart cherries.
They reported their findings in the Journal of Agricultural and Food Chemistry (2001 Oct;49(10):4898-902): "The implication…is that consuming cherries could be an important source of dietary melatonin inasmuch as melatonin is readily absorbed when taken orally."In 2003, scientists reported in The Cancer Letter (Bourquin et al; May 8;194(1):13-9) that phytochemicals called anthocyanins, which are found in specially-enriched tart cherries, had been seen to inhibit the development of tumors in mice and reduce the proliferation of human colon cancer cells.
In 1950 a study investigated a cherry diet as a control for gout and arthritis (Blau LW, Tex Rep Biol Med. 1950;8(3):309-11). The mechanism for the anti-gout effect was more recently explained by Kader et al in the Journal of Nutrition (2003 Jun;133(6):1826-9), in a study which observed a decrease in plasma urate in cherry consuming women.
As to cherries' role in heart health, research is currently underway at Michigan State University to assess the effect of tart cherries on c-reactive protein, a biomarker for cardiovascular risk.
But the health claims legislation in the United States is strict: only after a body of evidence to support a health claim for a particular food or ingredient has been submitted, reviewed and approved by the FDA can products carry specific wording about health-promoting properties.
There are three different types of health claim: 'unqualified' health claims must meet the Significant Scientific Agreement standard, whereas 'qualified' health claims acknowledge the benefit of providing consumers with information on labels concerning diet and health even if the science is only 'somewhat settled' (ie does not need the Significant Scientific Agreement standard).
The third type, structure/function claims, refer only to the effect that a substance has on the structure or function of the body, nor a specific disease. For example, "calcium builds strong bones".
In the absence of formal health claims linking cherries to a reduce risk of any disease or specific effect on the body, the FDA told the companies that wording on their websites and/or product labels constitutes "serious violations of the federal Food, Drug, and Cosmetic Act".
It warned that enforcement action may be carried out if these violations are not promptly corrected - which could include seizure of products, injunction against manufacturers and distributors, and criminal sanctions.
Phil Korson, executive director of the Michigan Cherry Committee, told NutraIngredients-USA.com that he was surprised at the warning letters.
"We are trying to sort out the connection between the websites and the labeling," he said.
"The industry continues to invest in research, and the evidence is very compelling."
He added that there is a danger the FDA's action could prove damaging to the industry.
"People don't understand the background behind this. When a warning letter goes out we take it very seriously. We want companies to be in compliance." Eighteen of the 29 companies that received warning letters are based in Michigan, and many are small, family-run enterprises.