U. S. Food and Drug Administration
January - February 1999
What Are Sprouts?
How to Eat Sprouts Safely
Sprouting About Sprouts
by Paula Kurtzweil
Sprouts--those crunchy, healthy newborn plants
often associated with the hippie days of the 1960s--have in this decade become regulars in
salad bars and produce departments across the country. But along with their increasing
presence has come an increasing frequency of sprout-related food-borne illness.
The federal government has linked the most common
kind--alfalfa sprouts--to a number of food-borne disease outbreaks, most occurring since
1995. The disease culprits included the bacteria Salmonella and Escherichia coli O157:H7,
a particularly dangerous pathogen.
These outbreaks led the Food and Drug
Administration in August 1998 to issue a health advisory for high-risk groups warning them
not to eat raw alfalfa sprouts and, in September, to conduct a public hearing to determine
what further steps, if any, are needed to ensure the safety of sprouts.
"There are some interesting questions raised
about sprouts," says Karen Hulebak, a science policy analyst in FDA's Office of
Policy. "What do we know about the source of sprout contamination? What should
consumers do? ... There are a lot of uncertainties."
What Are Sprouts?
Sprouts, which are the germinating form of seeds
and beans, are easy to produce. They require no soil, only water and cool temperatures.
They emerge in two to seven days, depending on the type of seed or bean. In addition to
raw alfalfa sprouts, other varieties include clover, sunflower, broccoli, mustard, radish,
garlic, dill, and pumpkin, as well as various beans, such as mung, kidney, pinto, navy and
soy, and wheat berries. Many are sold individually, some in mixtures.
Potomac Glen Farms in Potomac, Md., sells a wide
array. Each offers a distinct flavor, suggesting, as sprout growers like to point out,
that sprouts indeed work well in a variety of dishes, such as soups, salads, sandwiches,
and stir fries. Nancy Snider, owner of Potomac Glen Farms and president of the
International Sprout Growers Association, says one of her favorite foods is sprouts with
peanut butter and crackers.
While versatile, sprouts also are favored for
their nutritional value. Like other fresh produce, sprouts are low in calories and fat and
provide substantial amounts of key nutrients, such as vitamin C, folate and fiber. A 1997
Johns Hopkins University study suggested raw broccoli sprouts may be particularly rich in
sulforaphane, a compound that may mobilize the body's natural cancer-fighting resources
and reduce the risk of developing cancer.
Though popular in this country in only the past
few decades, sprouts have actually been around for thousands of years. Mung beans have
been used in Chinese foods for years--though usually in cooked dishes.
Today, sprouts in the United States are a
$250-million market. Some 475 U.S. sprout growers produce 300,000 tons of sprouts every
year, according to the International Sprout Growers Association. As many as 10 percent of
Americans eat sprouts regularly.
Sprouts have only recently emerged as a recognized
source of food-borne illness. Since 1995, health officials have attributed 13 food-borne
disease outbreaks worldwide to sprouts. Ten of these outbreaks occurred in the United
States, resulting in illnesses in at least 956 Americans and at least one death.
Four of the outbreaks were caused by E. coli
bacteria, and three of those involved the most dangerous strain, E. coli O157:H7. The
biggest outbreak occurred in Japan in 1996; 9,000 people were sickened and 17 died after
eating radish sprouts contaminated with E. coli O157:H7.
The O157:H7 strain produces toxin in the human gut
that damages cells of the intestinal lining. This allows blood to pass into the stool.
Other symptoms of O157:H7 infection are stomachache, nausea and vomiting. Infection can
lead to hemolytic uremic syndrome (HUS), a major cause of acute kidney failure in children
in this country. HUS is fatal in about 3 to 5 percent of cases.
Many of the outbreaks have involved raw alfalfa
sprouts or mixed sprouts containing raw alfalfa sprouts contaminated with Salmonella.
In people, Salmonella can cause salmonellosis, an
illness characterized by fever, stomach cramps, and diarrhea. The illness can last as long
as seven days, and severe cases may require hospitalization. In some people, it can cause
death. A small number of illnesses may develop into recurring joint pain and arthritis.
Where do these bacteria come from? It's believed
that the seeds from which sprouts are derived are often the source. Some of the seeds may
become contaminated by animals in the field or during post-harvest storage, for example.
Also, the use of animal manure in fields of alfalfa intended for nonhuman use may be a
problem if seed is used for sprouting.
The ideal conditions provided by germinating seeds
and beans--namely abundant nutrients in this phase of plant growth, high levels of
moisture needed to produce sprouts, and heat generated from the sprouting process--help
ensure the survival and growth of bacteria. "In the sprouting environment, bacteria
can grow quickly," says Robert Wick, Ph.D., a plant pathologist with the University
of Massachusetts and one of the presenters at FDA's September 1998 public hearing on
So far, mishandling of sprouts during production,
packing or distribution has not been implicated as the source of sprout contamination.
However, bacteria already present in the sprouting seed can continue to thrive in
conditions in which poor food handling techniques are practiced--for example, lack of
refrigeration, infected workers, and dirty and unsanitary sprouting facilities.
Following three 1998 food-borne disease outbreaks
involving raw alfalfa sprouts, FDA in August reaffirmed a warning that had been issued by
the national Centers for Disease Control and Prevention in 1997. The advisory urged people
at high risk for severe food-borne disease--children, the elderly, and people with
compromised immune systems--to avoid raw alfalfa sprouts until methods to improve the
safety of sprouts can be identified and put in place.
In September, the agency held a two-day public
meeting on sprout safety to learn, among other things, possible preventive measures to
ensure safe sprouts. Representatives from the sprout industry and consumer groups, as well
as scientists and regulators, presented information to the Fresh Produce Subcommittee of
the National Advisory Committee on Microbiological Criteria for Food.
High on the list of possible strategies was
decontamination of sprout seeds. The most promising method is chemical treatment with
calcium hypochlorite. It already is in use in California on an emergency basis, as
approved by the state's environmental protection agency. FDA is working with the U.S.
Department of Agriculture to get the treatment approved by the U.S. Environmental
Protection Agency, which oversees use of chemicals on raw agricultural products, such as
Irradiation, in which a measured dose of ionizing
radiation is applied to a food product, appears to work well in decontaminating sprout
seeds, especially when used in conjunction with calcium hypochlorite. Irradiation of
sprout seeds would require FDA approval.
Heat treatment (the same as pasteurization) has
limited appeal because there is such a fine threshold at which bacteria can be killed and
germination not destroyed.
Other preventive measures would focus on
production and distribution of sprouts. Possibilities include mandatory Hazard Analysis
and Critical Control Point (HACCP) programs for sprout growers. HACCP focuses on
identifying and preventing hazards, such as bacterial contamination, rather than relying
on spot-checks of production processes and random sampling of finished products. Emphasis
on good agricultural and manufacturing practices of sprouts also may help reduce the
incidence of sprout-related food-borne disease outbreaks. Another option might be to
include a list of safe handling practices or a mandatory warning on labels of sprout
packages. The warning would echo FDA and CDC recommendations for high-risk groups.
According to LeAnne Jackson, Ph.D., a science
policy analyst in FDA's Center for Food Safety and Applied Nutrition, the National
Advisory Committee on Microbiological Criteria for Food was awaiting the subcommittee's
recommendations at press time. If endorsed, the recommendations will be forwarded to FDA
In the meantime, the International Sprout Growers
Association planned to begin in November 1998 a voluntary quality assurance program in
which sprout growers agree to follow ISGA-established sanitation guidelines based on good
manufacturing practices. According to ISGA president Snider, sprout growers that
participate could label their products as ISGA-certified as long as their facilities pass
inspection by a third-party auditor.
The sprout industry also is working with the
National Center for Food Safety and Technology--a consortium of government, industry and
academia devoted to food safety research--in Summit-Argo, Ill., to study sprout safety.
The center is conducting a six-month research project to verify the effects of chemical,
heat and irradiation treatment of seeds on sprout safety.
Snider says the industry is involved because it
wants to reduce any hazards associated with sprouts. "This is a difficult time for
us," she acknowledges. "But out of difficulties, something good can come. We
expect [these concerns over sprout safety] to turn out to be our best friend. We want our
products to carry zero risk."
Paula Kurtzweil is a member of FDA's public
How to Eat Sprouts
If you belong to one of the groups at high risk
for food-borne disease--children, the elderly, and people with compromised immune
systems--avoid raw alfalfa sprouts.
If you are a healthy adult, follow these tips:
- Buy only sprouts kept at refrigerator temperature.
Select crisp-looking sprouts with the buds attached. Avoid musty-smelling, dark, or
- Refrigerate sprouts at home. The refrigerator
should be set at no higher than 40 degrees Fahrenheit (4 degrees Celsius).
- Wash hands with warm water and soap for at least 20
seconds before and after handling raw foods.
- Rinse sprouts thoroughly with water before use.
Rinsing can help remove surface dirt. Do not use soap or other detergents.