FAQs Frequently Asked Questions
Q. Why eat 5 or more servings of fruits and vegetables a day?
A. Over 200 studies showed that people who eat 5 or more servings of fruits and vegetables daily have only half as many digestive and respiratory cancers as those who consume fewer than 2 servings a day. Many other studies have confirmed that a diet high in fruits and vegetables reduces the risks of obesity, heart disease, stroke and diabetes, as well as many forms of cancer.
Q: What do you mean by a serving?
A. One serving is a piece of fruit, 1/2 cup chopped fruit, 1/2 cup cooked vegetable, 3/4 cup juice, 1 cup leafy vegetable, or 1/4 cup dried fruit.
Q: Does 5-a-Day mean I should eat 5 servings of fruits and 5 servings of vegetables each day?
A. No, it means a total of 5 servings of fruits and vegetables combined.
Q: Where does food come from?
A. Food in the U. S. is hauled an average of 1,300 miles from the farm to the market shelf.
Q: What is Community Supported Agriculture?
A. Community Supported Agriculture (CSA) is a way to get the best produce for your table and to help strengthen the local farm economy at the same time. It began in the 1960's with a Japanese movement called teikei or "putting the farmers' face on food."
Q. Do beans count towards 5-a-Day?
A. Yes. And not just green beans. Pinto beans, black beans, soybeans, lima beans, etc. all count towards your 5-a-Day.
Q. Do potatoes count?
A. Unless they have a lot of added oil or fat. Fried vegetables like french fries, potato chips, onion rings, etc. don't count for 5-a-Day.
Q: Do frozen and canned fruits and vegetables count?
A. They do.
Q: What if I eat more than 5-a-Day?
A. That's great. Many nutritionists think we should be eating 9 a day, but it was so far from what Americans were eating that 5-a-Day was thought to be a more attainable goal. It may be raised in the future after Americans become accustomed to eating more fruits and vegetables.
Q: What about pesticides on fruits and vegetables?
A. The evidence that fruits and vegetables help protect against cancer and heart disease and other diseases is much stronger than the evidence that pesticides on the produce we eat cause health problems. The advantages of eating fruits and vegetables far outweigh the disadvantages.
Q. How can I reduce the amount of pesticides on my produce?
A. Consider growing a garden or buying organically grown produce. Washing produce well with water can reduce pesticide residues by 30% - 100%. Peeling the produce skins and removing the outer leaves of lettuce and cabbage greatly reduces pesticide levels in produce.
Q. What's so great about green leaves?
A. The green leaves of plants power almost all life on earth by converting the sun's energy into forms that animals, including humans, can use. Put another way, virtually all the food we eat is created in green leaves before being relocated into fruits, grains, tuber, meat, milk , and eggs. There are nearly 1000 species of plants known to have edible leaves. Green leaf crops produce more nutrients per acre than any other crop. Dark green leafy vegetables are low in calories, have no cholesterol, and are rich in vitamins, minerals, fiber and cancer fighting antioxidants. Eating more of them helps reduce the risk of heart disease and gastrointestinal problems as well as cancer.
Q. If greens are so great, why don't people eat more of them?
A. Greens, such as spinach or kale are typically about 85% water. This makes them very perishable. Without refrigeration, which most of the world's people lack, greens become an uninviting wilted mess in a day or two. In much of the world a prolonged period of cold or dry weather is normal and as a result fresh greens are not available much of the year.
Many greens have a tough stringy texture that makes them especially unappealing to children who are developing lifelong eating habits. This texture makes greens difficult to incorporate in many foods and is partly responsible for pushing greens into a secondary side dish role at the human supper table.
Another factor limiting the popularity of greens is the strong slightly bitter flavor of some of them. Children are especially sensitive to bitter flavors because the taste buds are very close together on their tongues. As a result, many people develop a dislike for greens as children.
Q. Can anything be done to reduce these limitations?
A. Yes. Drying greens and grinding them to a fine meal eliminates the short shelf life problem and the stringy texture problem. It also allows us to add greens to a much greater variety of foods. With dried leaf meal you can offer children greens in foods they really enjoy, such as spaghetti, birthday cakes, and dinosaur shaped cookies.
Q. What is fiber and why is it important in the human diet?
A. Fiber refers to a variety of indigestible substances in plant foods. There are two basic forms of fiber. Water insoluble fibers, which make up the structural parts of plant cell walls, include substances like cellulose, hemicellulose, and lignin that are found primarily in whole wheat products, wheat bran, and fruit and vegetable skins. Water soluble fibers come primarily from fruits, vegetables, beans, and oats, and include pectins and gum.
Insoluble fiber is important in maintaining a healthy digestive tract. It absorbs water and speeds the transit time of waste moving through the large intestine. This reduces the risk of constipation, hemorrhoids (swollen distended veins in the rectal area), and diverticulosis (a common ailment that develops pouches in weak areas of the large intestine). There is some evidence that a good supply of insoluble fiber also reduces the risk of colon cancer. This is one of the most common cancers in the industrialized countries and has about a 50% mortality rate. In parts of the world where dietary fiber intake is high, colon cancer rates are extremely low.
Soluble fibers, such as oat bran, have been reported to lower blood cholesterol and thus the risk of heart disease. These fibers have also reduced insulin requirements in some people with adult-onset diabetes. Both of these effects are still being studied, so these results should be considered preliminary.
Q. Is there a danger of getting too much fiber in the diet?
A. In industrialized societies the danger from too little fiber far outweighs the danger of too much. For adults 25 - 35 grams of fiber per day are recommended (Americans consumes just 11 grams of fiber per day on average). For children the recommendation is 5 grams of fiber plus an additional gram for each year of age. A tablespoon of leaf powder contains about 1 -2 grams of fiber.
A diet very high in fiber makes calcium, iron and zinc more difficult to absorb. This usually is a problem only when pregnant women and children have a marginal intake of these minerals combined with a very high intake of fiber.
Q. Aren't most nutrients destroyed when greens are cooked?
A. The USDA Composition of Foods estimates that dark green leafy vegetables that have been boiled and drained retain the following percentages of essential nutrients that were present in the raw leaves:
Q. What is the most common nutritional deficiency disease in the world?
A. Iron deficiency anemia is considered the most common nutritional deficiency, affecting roughly 50% of the women of childbearing age and 40% of the children under five years in developing countries. Anemia is an insidious condition that causes fatigue, apathy, lowered resistance to infection, and reduced mental functioning. It is most common where people can't afford meat, which contains iron in an easily absorbed form. While iron from meat and fish is better utilized, vegetable sources of iron can meet the body's requirements. Iron from vegetable sources is absorbed up to four times better when it is eaten with a source of vitamin C, such as fruit juice or fresh greens. Dark green leafy vegetables are inexpensive foods that are rich in iron and could greatly reduce anemia throughout the world.
Q. What are antioxidants and why are they important?
A. Antioxidants are compounds that combine with and neutralize the highly reactive free radicals that otherwise can damage the cell walls throughout our bodies. Free radicals come from by-products of normal bodily processes such as the digestion of food, and from environmental factors such as cigarette smoke, ultraviolet radiation in sunlight, and a range of industrial chemicals that people are exposed to routinely. Unless they are neutralized by antioxidants they will "steal" electrons from molecules in our cell walls. These molecules then become unstable and a chain reaction is initiated that can contribute to a variety of chronic health problems, including cancer and heart disease.
Your body depends on a continual supply of a range of different antioxidants to neutralize different free radicals. Some antioxidants are enzymes created within your body, notably superoxide dismutase, glutathione peroxidase, and catalase. Others are nutrients from our diet, including beta-carotene, vitamin C, vitamin E and selenium. Some of the other known antioxidants and important food sources of them are:
Q. Why do turnip greens and kale taste better after a frost?
A. When winter temperatures arrive, hardy greens try to protect their leaf tissues from freezing by converting some stored starch into soluble sugars. The presence of the dissolved sugar lowers the temperature at which the plant sap will freeze by several degrees. When the sap or juice in the these plants does freeze, it expands and ruptures cell walls and other structures, often killing the plant. We generally prefer the flavor of the greens with the increased sugar content.
Q. What is folacin and why is it important ?
A. Folacin, folic acid, and folate, are different names for an essential B vitamin. The name comes from the same root as foliage because it is plentiful in the leaves of plants. It is required by the body for DNA metabolism and plays an important role in genetic functions such as cell division and tissue growth. Folacin is also involved in the formation of hemoglobin in red blood cells. A lack of folacin during pregnancy can lead to miscarriage and birth defects such as spina bifida (exposed spinal cord).
Foods that are high in folacin include dark-green leafy vegetables, liver, kidneys, fruits, and beans and peas. However, since folacin is easily destroyed by oxidation, the vitamin may be lost by overcooking or processing of foods.
Except in prescribed pre-natal vitamins, taking large amounts of folic acid in supplement form is not advised because it can mask the symptoms of a serious vitamin B-12 deficiency.
Q. I've tried spinach, kale, collards, Swiss chard, mustard and turnip greens. What other dark green leafy vegetables are there?
A. Cornucopia: The Handbook for Edible Plants by Stephen Facciola lists 983 species of plants with leaves that are edible to humans.
Q. Which leaf crops are the most nutritious?
A. Generally speaking, the darker green the leaves are, the more nutritious they are as food. Plants make vitamin C from sugars, which are supplied by the leaves as the product of photosynthesis. So the more light a plant gets, the more photosynthetic activity there is, the more sugars are produced, and the more plentiful is the vitamin C. In addition, the more light a plant gets, the more pigments-both chlorophylls and carotenoids-are needed to handle the energy input, and so the darker the coloration of the leaves and stem surfaces. Carotenoids include beta-carotene, the precursor to vitamin A, and antioxidants, such as lutein. So the darker the color of a leafy vegetable, the more vitamin C, vitamin A precursor, and antioxidants it is likely to contain. Leaves that are not exposed to sunlight such as the inner leaves of head cabbage and head lettuce have less than 5% of the beta-carotene as the outer leaves of the plant.
Consider, for example, that a serving of dark green kale (Brassica oleracae) contains 4.5 times more protein, 4 time more iron, 9 times more calcium, 19 times more vitamin C, and 26 times more vitamin A than the same amount of iceberg lettuce.
Q. How are organically grown greens different than non-organically grown greens?
A. Greens grown by organic methods will usually have somewhat lower levels of nitrates in the leaves. These are compounds that can be converted to carcinogenic nitrites either within your body or by bacterial action in food left out at room temperature. Organically grown greens should be free from pesticide residues, unlike industrially grown greens. Other than that, the nutritional composition of the two is very similar. Some of the minerals, like iron, are affected by how much of the mineral is in the soil in which the plants are grown, but most other components of greens are genetically pre-determined.
More significant nutritional differences are found between different varieties of a leaf crop than between organic and non-organic versions of the same crop. Besides genetics, the most important factor in the nutritional value of greens is the length of time between harvest and eating. This is where home gardens shine. For the very best greens select nutritious varieties, grow them organically, and eat them immediately after harvest. For those unable to grow their own greens, for whatever reason, the best strategy is to buy them as fresh and as locally grown as possible.
In my opinion, the biggest value of organic agriculture is not in producing better food so much as in maintaining a healthy soil structure through better management of organic matter. This has a great many benefits on the entire ecosystem involved, one of which is the ability to produce human food in the future.
Q. What common weeds are edible?
A. Some of the more common weeds are also edible and nutritious greens. These include dandelions, lambsquarters, pigweed, purslane, plantain, chickweed, and sorrel.
Q. Can we eat leaves from trees?
A. The leaves from most trees are too tough and fibrous to be of much use in our diet. Also it is inconvenient harvesting young green leaves from tall trees and they are far too fibrous by the time they fall.
Despite these limits, there are a number of tropical and sub-tropical trees and perennial shrubs whose leaves are eaten locally. These include Indian mulberry, Sesbania grandiflora, Acacia nilotica, Cassia obtusifolia, and Baobab. Moringa oleifera (Horseradish or Drumstick Tree) is probably the best of all trees for edible and nutritious leaves. It is small, fast growing and pan-tropical . Tropical tree leaves tend to vary genetically from tree to tree and place to place in the amount of alkaloids and other toxins they contain.
Q. Are some leaves poisonous?
A. Yes. Socrates was reportedly executed by being forced to drink the juice from the common water hemlock, a parsley relative. Diffenbachia, or dumb cane, is a relatively common houseplant whose foliage has caused poisonings in many children. Daffodil leaves are poisonous. In the vegetable garden tomato, potato, and rhubarb leaves are toxic. Poke and comfrey are two common plants whose leaves used to be considered health giving, but are no longer considered safe to eat. To avoid possible poisoning from plant leaves use the following:
Q. What is the best way to cook greens?
A. Generally, greens retain the best combination of color, texture, and nutritional value when they are cooked very quickly at a high temperature. Stir frying is good because a temperature higher than that of boiling water is used and pieces are cut quite small. Microwave ovens also cook greens very quickly and don't allow water soluble vitamins to be lost in cooking water. To retain the brightest color, greens must pass as quickly as possible through the temperature range of 150° - 170° F. (66° - 77° C.). Within this temperature range the enzyme chlorophyllase, which breaks down the green pigment chlorophyll, is most active. Putting leaves in a large volume of boiling water is good for color but bad for losing water soluble vitamins.
Q. What is the best way to preserve leaves?
A. From a nutritional point of view, freezing is probably the best and canning the worst. Drying leaves is excellent if it is done well. That is at about 120° F (50° C), with a good flow of air, and out of direct sunlight. Dried leaves can be ground to a fine leaf meal which is more versatile in recipes than other forms of greens.
Even more versatile, though significantly more difficult to prepare, is dried leaf concentrate. Leaf concentrate is made by pressing the juice from pulped fresh green leaves and coagulating that juice by heating it quickly to the boiling point. The curd that floats to the top of the heated juice is pressed and crumbled, then dried in the same manner described above. Almost all of the fiber is removed by this process making a product with very different texture than the greens. Leaf concentrate can only be made from certain leaf crops, as the juice from many will not coagulate well.
Some cultures make fermented products from leaves to preserve them. These include the relatively well known sauerkraut and kim chi, and more obscure products, such as kawal , made from fermented cassia leaves in parts of Africa. While the fermentation process improves the digestibility of some nutrients, generally fermented leaf products are excessively high in salt and have lost much of the initial vitamin content of the greens. They are often so strongly flavored that they are used in small quantities to spice up other foods.
Q. What is leaf concentrate or leaf protein and how is it different from dried green leaf powder?
A. Leaf powder is the whole leaf dried with the stems sifted out. Leaf concentrate or leaf protein, as it was originally called, is made by coagulating juice pressed from certain green leaves. Virtually all of the fiber has been removed. Leaf concentrate is a more expensive product made by a more complex process. Leaf concentrate is extremely rich in nutrients and is about 55% protein when dried. It is an excellent food for rehabilitating malnourished children. Dried leaf powder is much easier to make at home and is intended for day to day use by people trying to maintain basically good health.
Q. Can I just dry leaves in the sun?
A. No. Beta-carotene is quickly destroyed by exposure to direct sunlight. It is much better to dry leaves in a simple solar dryer with a covering that captures the heat of the sun without allowing the sun's ultraviolet rays to pass. Greenhouse grade polyethylene film is excellent for this. A 6 mil thick ultraviolet blocking film rated for three years costs under US $ 0.10 per square foot (about US $1.0 per square meter). This and other ultraviolet blocking glazing that will work for solar dryers is sold by several greenhouse supply companies. Unfortunately they often sell only very large sheets. For example, Rough Bros in Cinncinati (1-800- 543-7351) sells a 25 ' X 100' sheet of 6 mil 3 year poly for US $ 145.00 plus shipping.
Q. Isn't it easier to get people to take vitamin capsules or to fortify common foods with lacking nutrients than to get people to change their eating habits?
A. It is generally agreed that, while it may be difficult, the most lasting way to improve people's nutritional status is by incorporating more nutritious foods into the normal diet. Increasingly we see health benefits from eating a complex range of vegetables that cannot be duplicated with capsules or fortification programs. We believe in showing people the value of eating more leafy greens and teaching them improved methods of growing and preparing them. When this is successful, the people's diet and health are improved without a long term dependence on chemical companies, like Hoffman-LaRoche, and government agencies to oversee the distribution of essential nutrients.
Q. What is the deal with products like Spirulina, Super Blue-Green Algae, and Magna Green that I've seen in health food stores?
A. Spirulina and Super- Blue Green Algae are algaes grown in alkaline waters that have been dried and ground. Algaes, which include seaweeds, are simple plants that grow in water and lack the indigestible fiber cell wall of land plants. They are extremely nutritious, and are much appreciated foods in many cultures. Magna Green is made from the dried juice of young barley plants mixed with brown rice.
The drawback with these products and many others like them is that the price is completely out of proportion to their nutritional value. Unless you are wealthy, you are better off drying your own greens. It is simple and inexpensive and yields a product of very similar nutritional value.
Q. How about wheat grass juice? I was told it was very good for you but it made me nauseous.
A. Wheat grass juice has been promoted as a super food by Ann Wigmore and her Boston based group for over 40 years. It is juice pressed from 7-10 day old wheat plants grown inside in trays. The presence of simple sugars in the juice makes some people nauseous.
If you have the space it is much easier to let the wheat plants grow normally outside than to fuss with growing them in trays indoors. Like most plant leaves, wheat leaves reach their nutritional peak just before the plant begins transferring nutrients from the leaves to the reproductive system for creating seeds. Spring wheat takes about a month to do this, and winter wheat planted in Kentucky in October won't peak until April. When it is about ten inches high, harvest the top half of the plants and dry these leaves (wheat grass). At this stage it is much more complete nutritionally and less likely to cause stomach upset. The powdered dried wheat grass can add nutrition to a variety of drinks, pasta, and other foods. It is inexpensive, very nutritious, and far more versatile to use than the wheat grass juice.
Some health food advocates claim that the enzymes in raw foods like wheat grass juice have important benefits, but plant enzymes are proteins that are broken down into amino acids like other proteins we eat, and then reassembled into new proteins including enzymes that humans need. Enzymes function in very complex and specific biochemical environments. Our bodies protect us from foreign enzymes disturbing our body chemistry by reducing them to components that we can either burn as fuel, use to create new tissue, or make new enzymes with, as needed. The only exceptions are a few digestive enzymes that are able to briefly hold their own in our digestive tracks.