FIBER

Definition

Dietary fiber is found in plant foods. Fiber cannot be digested by humans. It has no calories because the body cannot absorb it.

Food Sources
There are two forms of fiber: soluble and insoluble. Soluble fiber attracts water and turns to gel during digestion. This slows digestion and the rate of nutrient absorption from the stomach and intestine. It is found in oat bran, barley, nuts, seeds, beans, lentils, peas, and some fruits and vegetables. Insoluble fiber is found in foods such as wheat bran, vegetables and whole grains. It appears to speed the passage of foods through the stomach and intestines and adds bulk to the stool.

功能
规定饮食的纤维提供成熟的感情和加进容积日常饮食。这帮助消化力和除去。

Including fiber in your daily diet helps prevent many problems and brings many benefits. It may be helpful in controlling weight by making you feel full sooner. It helps prevent constipation. It may be helpful in the prevention or treatment of diverticulosis, diabetes, and heart disease (ask your health care provider or registered dietician about recommendations for these conditions).

Recommendations
The average American now eats 10 to 15 grams of fiber per day. The recommendation for older children, adolescents and adults is 20 to 35 grams per day. Younger children will not be able to eat enough calories to achieve this, but introducing whole grains, fresh fruits and other high fiber foods is suggested. To ensure an adequate fiber intake, eat a variety of foods, including more fruits, vegetables, whole grains, cereals, and dried beans and peas. Add fiber gradually over a period of a few weeks to avoid abdominal discomfort. Water aids the passage of fiber through the digestive system. Drink plenty of fluids (approximately 8 glasses of water or noncaloric fluid a day).

Peeling can reduce the amount of fiber in a food. Cooking may actually increase your intake by decreasing the volume of the food that is prepared.

Side Effects
Eating a large amount of fiber in a short period of time can cause intestinal gas (flatulence), bloating, and abdominal cramps. This subsides once the natural bacteria in the digestive system get used to the increase in fiber in the diet. The problem with gas or diarrhea can be reduced considerably by adding fiber gradually to the diet.

Too much fiber may interfere with the absorption of trace minerals including iron, zinc, magnesium, and calcium. This effect is minimal because high-fiber foods are usually rich in minerals.

ZINC

Definition
Zinc is one of the most common elements in the earth's crust and is present in all foods. It is an essential element for our bodies.Zinc deficiency is fairly common now as a result of soil losses and losses in food processing, and this deficiency or depletion can produce a variety of symptoms.

Food Sources

Most animal foods contain adequate amounts of zinc. Oysters are particularly high, with more than ten times as much as other sources. Zinc is added to animal feeds to increase growth rates, so meat usually contains high amounts. Red meats (beef, lamb, and pork) and liver are fairly high; herring is good, as are egg yolks and milk products (though the zinc in eggs and milk products may not be as available to the body as that found in other sources). Other fish and poultry also contain fair zinc levels. As with iron, the zinc in animal foods seems to be better absorbed than that in the vegetable sources, but one can reduce meat foods and eat whole grains and beans and still obtain adequate zinc.

Whole grains such as whole wheat, rye, and oats are rich in zinc and are good sources for vegetarians. Even though the mineral from these foods is utilized less well because the fiber and phytates in the grain covering bind some zinc in the gastrointestinal tract, much of the zinc in these foods is still available to the body. Nuts are fairly good sources, with pecans and Brazil nuts the highest. Pumpkin seeds contain zinc and are thought to be helpful to the prostate gland. Ginger root is a good zinc source, as are mustard, chili powder, and black pepper. In general, fruits and vegetables are not good zinc sources, although peas, carrots, beets, and cabbage contain some zinc.

The zinc in grains is found mainly in the germ and bran coverings, so refining them will lower the zinc content. Approximately 80 percent of zinc is lost in making white flour from whole wheat. Since zinc is soluble in water, canning foods or cooking in water can cause zinc losses. Zinc losses have also been prevalent in agricultural soils, and it is therefore less available in foods. Chemical fertilizers also decrease zinc soil levels. Many soils -nearly 30 states in the United States- are deficient in zinc. Water, especially from some wells, contains zinc. Water was a better source when some of the water pipes were galvanized (containing zinc), as were some cooking pots. Now, water pipes are more commonly made of copper, which can become toxic at higher levels.

Functions

Zinc is involved in a multitude of human body functions and is part of many enzyme systems. With regard to metabolism, zinc is part of alcohol dehydrogenase, which helps the liver detoxify alcohols, including ethanol (drinking alcohol), methanol, ethylene glycol, and retinol (vitamin A). Zinc is also thought to help utilize and maintain body levels of vitamin A. Through this action, zinc may help maintain healthy skin cells and thus may be helpful in generating new skin after burns or injury. By helping collagen formation, zinc may also improve wound healing. Zinc aids the skin's oil glands and so may help in acne problems.

Zinc is needed for lactate and malate dehydrogenases, both important in energy production. Zinc is a cofactor for the enzyme alkaline phosphatase, which helps contribute phosphates to bones. Zinc is also part of bone and tooth structure. Zinc is important to male sex organ function and reproductive fluids. It is in high concentration in the prostate gland as well as in the eye, liver, and muscle tissues suggesting its functions in those areas.

Zinc in carboxypeptidase (a digestive enzyme) helps in protein digestion. Zinc is important for synthesis of nucleic acids, both DNA and RNA. As part of superoxide dismutase (SOD), it helps protect cells from free radicals. Through this antioxidant effect, zinc is also helpful in cell membrane structure and function.

Zinc has also been shown to support immune function. Zinc will improve antibody response to vaccines and can improve cell-mediated immunity by helping regulate the function of the white blood cells. A somewhat higher amount of zinc has caused an increase in production of T lymphocytes, important agents in cell-mediated immunity.

Zinc is important to normal insulin activity and seems related to normal taste sensation. Zinc may have an anti-inflammatory function, especially in the joints and artery linings. It may also be involved in brain function, in maintaining acid-alkaline balance through carbonic anhydrase, another zinc-containing enzyme, and in phosphorus metabolism.

MAGNESIUM

Definition
Magnesium is a major mineral that is involved in more than 300 enzyme reactions in the body.

Food sources

Magnesium is found in nuts, soybeans, legumes and whole grains. It is also found in seafood, dark green vegetables, cereals, bananas, and milk. Following are some foods and the amount of magnesium in them:

Functions
Magnesium is an important mineral in bone structure. Magnesium works together withcalcium andphosphorus to form bones. It is also found in muscle, body fluids and soft tissue, such as the heart and kidneys. Magnesium helps changecarbohydrates,proteins, andfats to energy. It is involved in muscle relaxation and contraction, as well as nerve transmission.

Magnesium helps preventdental cavities by holding calcium in tooth enamel. It is needed to help preventcoronary artery disease and irregular heartbeats, orarrhythmias. It also helps to regulate body temperature. Because magnesium helps the body use calcium properly, getting enough magnesium aftermenopause helps promote healthy bones and avoidosteoporosis.

Information

Most Americans do not have enough magnesium in their diet. Whole, natural foods are rich in magnesium. Many people eat only processed and refined foods. Processing food and water removes a lot of magnesium. Softened water replaces calcium and magnesium with sodium.

Although clinical deficiency is rare, minor deficiency is more common. A low level of magnesium in the diet can increase the chances forcoronary artery disease,high blood pressure, andkidney stones. Low levels of magnesium may also contribute tosleep disorders,premenstrual syndrome, and menstrual cramps.

Clinical deficiencies of magnesium can be caused by extremevomiting ordiarrhea.Malnutrition and alcohol abuse may also cause clinical deficiency. Long-term use of diuretics, or water pills,diabetes, and kidney disorders may cause magnesium deficiency. A deficiency of magnesium affects all tissues, especially the heart, nerves and kidneys.

High levels of magnesium taken from supplements, not from food and water, can cause gastrointestinal problems such asdiarrhea. Therefore the Tolerable Upper Intake Level, or UL, for supplementary magnesium is 350 mg. It is always smart to consult with a healthcare provider before beginning any supplement intake.

Toxicity from magnesium is rare, because the kidneys are good at removing excess magnesium. It can occur, however, in people with kidney disease. It can also occur in elderly people with weak kidney function. These people may not be able to excrete magnesium properly.

PECTIN

Definition
Pectin is a complex carbohydrate which cannot be absorbed from the intestinal system. It is used in the food industry as a thickening agent and in the production of jams and jellies.

Functions

Several studies have shown pectin to have positive influences on decreasing serum cholesterol levels, without effecting serum triglyceride levels. Pectin has also shown the ability to reduce the rise of blood sugar when combined with a meal. These effects have been demonstrated in both healthy individuals and those with diabetes (Jenkins).

Information

The search for ways to reduce weight in obese individuals is never-ending. Recently, it is more imperative that scientists discover safe ways for overweight individuals to shed pounds. It appears that ingesting certain fibers could play a role. Pectin is certainly one possibility. However, there could be many others that could be beneficial, including psyllium. One significant uncertainty is whether overconsumption of these fibers could somehow interfere with the absorption of certain vitamin, nutrients, and minerals. However, for the time being, it appears that adding a small amount of pectin or other fiber supplement to a meal would seem like a reasonable approach to enhance satiety, and certainly much safer than currently available pharmaceutical approaches.