Lettuce (Lactuca sativa) is an annual plant of the daisy family, Asteraceae. It is most often grown as a leaf vegetable, but sometimes for its stem and seeds. Lettuce is most often used for salads, although it is also seen in other kinds of food, such as soups, sandwiches and wraps; it can also be grilled. One variety, the woju (t:萵苣/s:莴苣), or asparagus lettuce (Celtuce), is grown for its stems, which are eaten either raw or cooked. In addition to its main use as a leafy green, it has also gathered religious and medicinal significance over centuries of human consumption. Europe and North America originally dominated the market for lettuce, but by the late 20th century the consumption of lettuce had spread throughout the world. World production of lettuce and chicory for calendar year 2017 was 27 million tonnes, 56% of which came from China.

Generally grown as a hardy annual, lettuce is easily cultivated, although it requires relatively low temperatures to prevent it from flowering quickly. It can be plagued by numerous nutrient deficiencies, as well as insect and mammal pests, and fungal and bacterial diseases. L. sativa crosses easily within the species and with some other species within the genus Lactuca. Although this trait can be a problem to home gardeners who attempt to save seeds, biologists have used it to broaden the gene pool of cultivated lettuce varieties.

Lettuce is a rich source of vitamin K and vitamin A, and a moderate source of folate and iron. Contaminated lettuce is often a source of bacterial, viral, and parasitic outbreaks in humans, including E. coli and Salmonella.

The nutritional value of lettuce varies with the variety. In general, lettuce provides small amounts of dietary fiber, some carbohydrates, a little protein and a trace of fat.
Iceberg is a head lettuce that is very low in nutritional value and flavor. The most abundant nutrient in iceberg lettuce is water. Dark green lettuce leaves always indicate higher fiber, flavor and nutritional value.

• The spine and ribs of lettuce provide dietary fiber, while vitamins and minerals are concentrated in the delicate leaf portion.
• The most important nutrients in lettuce are vitamin A and potassium.
• The vitamin A comes from beta carotene (beta-carotene is converted to vitamin A in the body), whose yellow-orange is hidden by green chlorophyll pigments.
• Lettuce, except iceberg, is also a moderately good source of vitamin C, calcium, iron and copper.
• Look for salad greens that are darker green in color. Iceberg lettuce has little nutritional value.
• One cup of raw leaf lettuce has 9 calories, 1 gram of protein, and 1.3 grams of fiber.
• If possible, do not cut or slice lettuce leaves in advance. Damaged, cut lettuce leaves release an ascorbic acid oxidase, which destroys vitamin C and causes the cut edges to discolor.

As you enjoy fresh produce, follow these safe handling tips to help protect yourself and your family.

Fruits and vegetables are an important part of a healthy diet. Your local markets carry a wide variety of nutritious fresh fruits and vegetables. However, harmful bacteria that may be in the soil or water where produce grows can come in contact with fruits and vegetables and contaminate them. Fresh produce may also become contaminated after it is harvested, such as during storage or preparation.

Eating contaminated produce can lead to foodborne illness, often called “food poisoning.” So as you enjoy fresh produce, follow these safe handling tips to help protect you and your family.

Buy Right

You can help keep produce safe by making wise buying decisions.

• Choose produce that is not bruised or damaged.
• When buying pre-cut, bagged or packaged produce — such as half of a watermelon or bagged salad greens — choose only those items that are refrigerated or surrounded by ice.
• Bag fresh fruits and vegetables separately from raw meat, poultry, and seafood when packing them to take home from the market

Store Properly

Proper storage of fresh produce can affect both quality and safety.

• Store perishable fresh fruits and vegetables (like strawberries, lettuce, herbs, and mushrooms) in a clean refrigerator at a temperature of 40° F or below. Use a refrigerator thermometer to check! If you’re not sure whether an item should be refrigerated to keep its quality, ask your grocer.
• Refrigerate all produce that is purchased pre-cut or packaged .

Separate for Safety

Keep fruits and vegetables that will be eaten raw separate from raw meat, poultry, and seafood — and from kitchen utensils used for those products.

• Wash cutting boards, dishes, utensils, and countertops with soap and hot water between preparing raw meat, poultry, and seafood and preparing produce that will not be cooked.
• If possible, use one cutting board for fresh produce and a separate one for raw meat, poultry, and seafood.
• If you use plastic or other non-porous cutting boards, run them through the dishwasher after use

Prepare Safely

When preparing any fresh produce, begin with clean hands. Wash your hands for at least 20 seconds with soap and warm water before and after preparation.

• Cut away any damaged or bruised areas on fresh fruits and vegetables before preparing and/or eating. Throw away any produce that looks rotten.
• Wash all produce thoroughly under running water before preparing and/or eating, including produce grown at home or bought from a grocery store or farmers’ market. Washing fruits and vegetables with soap, detergent, or commercial produce wash is not recommended. Produce is porous. Soap and household detergents can be absorbed by fruits and vegetables, despite thorough rinsing, and can make you sick. Also, the safety of the residues of commercial produce washes is not known and their effectiveness has not been tested.
• Even if you do not plan to eat the skin, it is still important to wash produce first so dirt and bacteria are not transferred from the surface when peeling or cutting produce.
• Scrub firm produce, such as melons and cucumbers, with a clean produce brush.
• After washing, dry produce with a clean cloth towel or paper towel to further reduce bacteria that may be present on the surface

What About Pre-Washed Produce?

Many pre-cut, bagged, or packaged produce items are pre-washed and ready-to-eat. If so, it will be stated on the packaging, and you can use the produce without further washing.

If you choose to wash produce marked as “pre-washed” or “ready-to-eat,” be sure that it does not come in contact with unclean surfaces or utensils. This will help to avoid cross contamination.

About Foodborne Illness

Know the Symptoms

Consuming dangerous foodborne bacteria will usually cause illness within 1 to 3 days of eating the contaminated food. However, sickness can also occur within 20 minutes or up to 6 weeks later. Although most people will recover from a foodborne illness within a short period of time, some can develop chronic, severe, or even life-threatening health problems.

Foodborne illness can sometimes be confused with other illnesses that have similar symptoms. The symptoms of foodborne illness can include:

• Vomiting, diarrhea, and abdominal pain
• Flu-like symptoms, such as fever, headache, and body ache

Take Action

If you think that you or a family member has a foodborne illness, contact your healthcare provider immediately.