What is nutrition?
Nutrition is the process of absorption of macronutrients and micronutrients from food to help the body grow and be healthy. Healthy or “balanced” nutrition begins by choosing foods from all of the food groups, which includes proteins, carbohydrates, fats, vitamins and minerals. A more varied diet helps the body meet all of its nutrient needs.

Macronutrients.  Macronutrients are defined as proteins, carbohydrates and fats. As a group, they provide the body with energy and help to maintain and regulate normal body functions. The average person should consume approximately 50% to 60% of their total daily calories as carbohydrate, 15% to 20% as protein and 30% as fat.

Proteins.  Amino acids are the basic building blocks of protein, and provide the raw material for all proteins. Protein is present in every living cell in the body. Our bodies use protein from the foods we eat to help build and maintain bone, muscle and skin. Around the world, millions of people don't eat enough protein. Protein malnutrition leads to a condition known as kwashiorkor. Lack of protein can cause growth failure, loss of muscle mass, decreased immunity, weakening of the heart and respiratory system and death. In the United States and other industrialized countries, eating the minimum daily requirement of protein is not difficult to do.

Protein is present in meat, dairy products, nuts and certain grains and beans. Protein from meat and other animal products are called “complete” proteins. This means that they supply all of the amino acids the body cannot make on its own. Plant proteins are “incomplete,” which means the body must ingest many different plant proteins to get all of the amino acids it needs to stay healthy. Because the body doesn't store amino acids, as it does for fat and carbohydrate, it needs a daily supply of amino acids to make new protein. It is important to eat enough dietary protein for bodily health. Healthy adults need a daily estimate of 0.8 grams of protein for every kilogram of body weight to keep from slowly breaking down organ tissues. That's just over 7 grams of protein for every 20 pounds of body weight, or 50-65 grams of protein each day. This is the amount of protein present in four ounces of meat plus a cup of cottage cheese.

Carbohydrates.  Carbohydrates come in a variety of forms, but the most common and abundant are sugars, starches and fibers. The basic building block of carbohydrates is the sugar molecule, a simple union of carbon, hydrogen and oxygen molecules. Starches and fibers are essentially chains of sugar molecules. Some of these chains are straight and contain only a few sugars, while others branch wildly and contain hundreds of sugars. Carbohydrates come from a wide variety of foods such as bread, beans, milk, popcorn, potatoes, cookies, spaghetti, corn and fruit. Carbohydrates were once grouped into two main categories as follows:

Simple carbohydrates include sugars such as fruit sugar (fructose), corn or grape sugar (dextrose or glucose), and table sugar (sucrose).

Complex carbohydrates include everything made of three or more linked sugars.
Simple sugars were once considered bad and complex carbohydrates good, but the picture is much more complex. The digestive system handles all carbohydrates in much the same way by breaking them down (or trying to break them down) into single sugar molecules small enough to enter the bloodstream. It also converts most digestible carbohydrates into glucose (blood sugar) because body cells are designed to use glucose as a universal energy source. Fiber is a carbohydrate exception. Fiber is put together in such a way that it cannot be broken down into simple sugar molecules, and passes through the body partially undigested.

Fats.  Fats are also referred to as lipids, and are made up of monounsaturated fats, polyunsaturated fats, saturated fats and cholesterol. Fats are a major source of energy and are important for proper growth and development, especially for infants and toddlers. Fat assists in the taste of food, is important to absorb fat-soluble vitamins (A, D, E and K) and provides satiety or a sense of feeling “full.” However, not all fats are the same as there are good and bad dietary fats. What is becoming clear is that bad fats increase the risk for certain diseases while good fats lower the risk.

Good Fats.  Some fats, called unsaturated fats, are good or healthy fats. Unsaturated fats are found in plant products such as vegetable oils, nuts and seeds. There are two types of unsaturated fats:

• Polyunsaturated fats are found in high concentrations in sunflower, corn and soybean oils.
• Monounsaturated fats are found in high concentrations in canola, peanut and olive oils.

Unsaturated fats are commonly used in the Mediterranean diet.  In studies in which polyunsaturated and monounsaturated fats were eaten in place of carbohydrates, these good fats decreased bad (LDL) cholesterol levels and increased good (HDL) cholesterol levels.

Bad Fats.  Saturated fats and trans fatty acids are bad fats because they tend to worsen blood cholesterol levels.

• Saturated fats are mainly animal fats. They are found in meat, seafood, high-fat dairy products (cheese, whole milk and ice cream), poultry skin and egg yolks. Some plant foods are also high in saturated fats and include coconut, coconut oil, palm oil and palm kernel oil. Saturated fats raise total blood cholesterol levels more than dietary cholesterol because they increase both HDL and LDL cholesterol. The net effect is negative, meaning it's important to limit saturated fats in the diet.


• Trans fatty acids are fats produced by heating liquid vegetable oils in the presence of hydrogen, a process called hydrogenation. The more hydrogenated an oil is, the harder it will be at room temperature. For example, a tub of spread margarine is less hydrogenated and has fewer trans fats than stick margarine. 

Most of the trans fats in the American diet are found in commercially prepared baked goods, stick margarines, snack foods and processed foods. Commercially prepared fried foods, like French fries and onion rings, also contain trans fat.

It is important to limit dietary intake of saturated fats, but it is very important to eliminate trans fats from the diet. Trans fats are the worst fats for health because they raise LDL and lower HDL levels (compared to saturated fats that raise both LDL and HDL cholesterol). Trans fats have been implicated in the vascular disease of heart attacks, stroke and diabetes.

• Cholesterol content of the diet is important, especially if one has diabetes, but it is the cholesterol level in the bloodstream that is most important for health risk. High blood cholesterol levels greatly increase the risk for heart disease. The liver is responsible for 75% of blood cholesterol, while only 25% is absorbed from food. The biggest influence of the diet on the blood cholesterol is the mix of fats that is consumed. The key is to substitute good fats for bad fats in the diet.

Micronutrients.  Vitamins and minerals are substances the body needs in small but steady amounts for normal growth, function and health. Together, vitamins and minerals are called micronutrients. The body cannot make most micronutrients, so it must get them from foods or dietary supplements.

Vitamins. Vitamins must be absorbed from food because the body cannot make them. The body only needs small amounts of vitamins (that's why they are referred to as micronutrients) and uses them without breaking them down. Vitamins are needed for a variety of body functions to include muscle and skeletal health, food digestion and nerve function. Vitamins are involved in many bodily processes that use carbohydrates, fats and proteins for energy and repair.

There are thirteen compounds classified as vitamins. Vitamins A, D, E and K are fat-soluble vitamins. They accumulate in the body and have a long body retention time. Vitamin C and the eight B vitamins (biotin, folate, niacin, pantothenic acid, riboflavin, thiamin, vitamin B6, and vitamin B12) are water-soluble. They do not accumulate in the body because excess amounts consumed are readily excreted by the kidney. Vitamins are labeled by "letter" or name, and some common vitamins include:

Vitamin A          = retinol, retinaldehyde, retinoic acid
Vitamin B1        = thiamin
Vitamin B2        = riboflavin
Vitamin B3        = niacin, nicotinic acid
Vitamin B12      = cobalamin
Vitamin C          = ascorbic acid
Vitamin D          = calciferol
Vitamin E          = tocopherol, tocotrienol
Vitamin K          = phylloquinone

Minerals. These micronutrients include calcium, magnesium and phosphorus.  They are the main components in teeth and bones and also serve as building blocks for all cells, help regulate body fluids, and are involved in nerve impulses and muscle function.

Signs and symptoms

Food labels. If you eat a healthy diet, do you need to take vitamins? Not long ago, the answer from most experts would have been a resounding "no.” The reason was that by eating a well balanced variety of foods one more than likely would consume all of the vitamins and minerals needed for health.  Nutritious eating includes: 

• Eating a variety of foods, including vegetables, fruits and whole-grain products.   
• Eating lean meats, poultry, fish, beans and low-fat dairy products.
• Limiting consumption of salt, sugar, alcohol, saturated fats and trans fats.
• Reading food labels to ensure a healthy diet.

One model for a “balanced” and nutritious meal would be to use the "plate method" for planning food portions:

• 50 percent as assorted vegetables
• 25 percent as protein
• 25 percent as whole grains (e.g., brown rice)
• One fruit

Vitamin deficiencies. Fat soluble vitamins may be deficient in diseases of malabsorption such as Celiac disease (sprue), cystic fibrosis, chronic pancreatitis, inflammatory bowel disease or short bowel from multiple bowel resections. Water soluble vitamin deficiencies are uncommon, but may be seen in wasting states (cancer, HIV, etc.), or after gastric bypass surgery during rapid weight loss and non-compliance with vitamin intake.  Vitamin and mineral deficiencies may cause the following signs or symptoms:

Vitamin A = difficulty seeing at night, xerophthalmia (corneal erosions and scarring), dry skin
Vitamin B1 = double vision (nystagmus, ophthalmoplegia), impaired gait, confusion, memory loss
Vitamin B2 = anemia, dermatitis, sore throat-mouth-tongue
Vitamin B3 = vomiting, hyperpigmented rash, diarrhea, disorientation-delusions-dementia
Vitamin B12 = anemia, abnormal gait and balance, impaired memory and irritability, dementia
Vitamin C = scurvy (poor wound healing, bleeding gums, petechiae, arthralgias, hyperkeratosis)
Vitamin D = osteomalacia or rickets (in children), bone loss, muscle weakness or spasm
Vitamin E = abnormal gait and balance, muscle weakness, neurologic abnormalities
Vitamin K = poor blood clotting, skin bruising

Conditions

Not Enough Fiber.  Fiber refers to carbohydrates that cannot be completely digested. Fiber is present in all edible plants to include fruits, vegetables, grains and legumes. However, not all fiber is the same. One way to categorize fiber is by its source of origin. For example, fiber from grains is referred to as cereal fiber. Another way to categorize fiber is by how easily it dissolves in water. Soluble fiber partially dissolves in water whereas insoluble fiber does not dissolve in water. These differences are important in understanding fiber's effect on the risk of developing certain diseases.

Fiber adds bulk to the diet and creates a sense of satiety (feeling “full” faster) and helps to control body weight. Fiber also aides in digestion and helps prevent constipation. Current recommendations suggest that adults should consume 21-38 grams of dietary fiber daily, depending on age and gender. Children aged 1 and older should consume at least 19 grams of fiber daily. The average American adult eats only 15 grams of dietary fiber a day. The following ideas may help to increase dietary fiber:

• Eat at least 4 to 5 cups of fruits and vegetables each day. Fruits that are high in fiber include apples, oranges, berries, pears, figs and prunes. Vegetables that are high in fiber include broccoli, cauliflower, brussel sprouts, green peas, carrots and beans
• Replace white bread with whole-grain breads and cereals. Eat brown rice instead of white rice. Eat more bran muffins, oatmeal, multiple-grain cereals (cooked or dry), brown rice, 100% whole-wheat bread and popcorn.
• Check labels on food packages for the amounts of dietary fiber, as some foods/brands may have less fiber than you think.

Fiber may cause abdominal bloating, cramping or flatus (gas). These symptoms can be prevented by making small changes in dietary fiber intake over a period of time. Start with one of the changes listed above, then wait several days to a week before making another. Drink more fluid (nine 8 ounce glasses daily for women, and twelve 8 ounce glasses daily for men) as liquids help to digest fiber.

Too Much Salt (Sodium).  About 11% of the sodium in an average American diet comes from adding salt (or sodium-containing condiments) to foods while cooking or eating. However, 77% of sodium consumed comes from eating prepared or processed foods that contain salt.
The kidneys regulate the amount of sodium in the body. If the kidneys cannot eliminate excess sodium, it accumulates in the blood, attracts and holds water, and increases blood volume and blood pressure which increases the work on the heart. Certain diseases such as congestive heart failure, cirrhosis of the liver and chronic kidney disease can retain sodium in the body. Individuals older than 50 years of age, African-Americans, or those with a health condition such as hypertension, chronic kidney disease or diabetes may be more sensitive to the blood pressure effects of sodium. The National Academy of Sciences' Institute of Medicine has published recommendations for daily sodium intake between 1500 and 2400 milligrams (mg) daily for healthy adults. The following may also help to control sodium intake:

• Eat more fresh foods and fewer processed foods. Most fresh fruits and vegetables are naturally low in sodium. Fresh meat is lower in sodium than luncheon meat, bacon, hot dogs, sausage and ham.
• Read labels. Remove salt from recipes whenever possible. Leave out the salt in many recipes, including casseroles, stews and other main dishes. (Baked goods are an exception, as leaving out salt may affect the quality and taste of the food.)
• Limit the use of condiments high in salt content. Salad dressings, sauces, dips, ketchup, mustard and relish all contain sodium.
• Use herbs, spices and other flavorings to enhance foods. Use salt substitutes wisely. Some salt substitutes contain a mixture of sodium and other compounds, and using too much salt substitute may not reduce sodium intake. In addition, many salt substitutes contain potassium that may be harmful if one has kidney problems, heart failure or is taking medication that retains potassium.

The taste for salt is acquired, so it's also reversible. Decreasing salt intake gradually allows the taste buds to adjust to a lower salt diet.

Pregnant with Diabetes. It is estimated that 8% of all pregnancies are complicated by diabetes. Approximately, 60% of these cases represent gestational diabetes (GDM), 30% type 2 diabetes and 10% type 1 diabetes. The estimated total number of pregnant women per year in the United States who have diabetes is up to 400,000 per year. Early diagnosis and maintenance of normoglycemia (normal blood sugar) during pregnancy dramatically reduces the risk of congenital birth defects, large for birth infants (macrosomia), birth related trauma and a host of other possible complications.

For these reasons, all pregnant patients should be tested for diabetes. Once the screening tests are completed, patients can then be educated in a proper balanced meal plan. The following guidelines are recommended for diabetes screening during pregnancy.

• Positive family history (parents, siblings, and children)
• Previous gestational diabetes
• Previous premature infant or unexplained stillbirth
• Prior large for birth ( ≥ infant with congenital anomaly
• Prior infant >/ = 4000 grams or ≥ 9 lbs)
• Poor reproductive history (infertility) or recurrent spontaneous abortions.
• Overweight (BMI > 25) or obese (BMI > 30)
• Elevated blood pressure or hypertension
• Glucosuria

If the GCT test results are abnormal, (> 130 mg/dl) initiate the GDM diet and Home Glucose Monitoring (HGM) immediately.

Home Glucose Monitoring (HGM) and Diet can help manage glucose levels during antepartum, the time of pregnancy between conception and onset of labor. HGM is performed by checking a finger stick blood glucose at morning fasting, (before breakfast), before (AC) and one hour post (PC) every meal. Glucose goals for HGM are as follows:

Fasting and AC </ = 90 mg/dl
PC glucose, 1-hour after the first bite of meal, ≤ 120 mg/dl

The goals of nutrition therapy during GDM to promote fetal well-being are to achieve normoglycemia, prevent ketosis and provide adequate weigh gain. Seek counsel from a registered dietician or use the Nutrition Jump Start teaching tool. You will then be able to identify the food that should be avoided and those that can be eaten to satiety.

Also, keep in mind the following calorie and BMI ratios:

• 30 Kcal/kg of present pregnancy body weight if the women’s pregnancy BMI is 19 to 24
• 24 Kcal/kg if her BMI is 24-29
• 18 Kcal/kg if her BMI is greater than 30
• 40 Kcal/kg if her BMI is less than 12

Patients should eat three daily meals with calorie distribution as 30% protein, 40% fat. Snacking should be de-emphasized and used only to abate hunger. Snacks are advised if unexpected low blood sugars occur during daily administration of insulin, but planned daily snacking should never be used to compensate for poor insulin placed on consistency of diet, exercise, and monitoring of glucose to achieve blood glucose control and appropriate weight gain during pregnancy.

For women with, “Low-Risk Diet Controlled GDM,” defined as meeting the home glucose monitoring (HGM) goals outlined above, the following is recommended:

• Diabetes diet and home glucose monitoring throughout pregnancy.
• Doctor office visits in high-risk clinic 2 weeks until 34 weeks gestation; then weekly.
• Begin antepartum surveillance at 39-40 weeks with biweekly nonstress testing of the fetus.
• Consider delivery by 40 weeks gestation or sooner for macrosomia (estimated Birth Weight > 4000 grams) or other maternal or fetal indications.

If the patient is at “high risk GDM” during antepartum when HGM goals are not met, Insulin Requiring GDM/Type 1 or Type 2 Diabetes, the following insulin therapy should be initiated:

Gestational Age:
6 – 12 weeks    0.7 U/kg day
12 – 28 weeks   0.8 U/kg day
28 – 36 weeks   0.9 U/kg day
36 – 40 weeks   1.0 U/kg day

Insulin should be prescribed such that 50% of the total daily dose is the basal insulin dosage and 50% is meal-related insulin dosage. The insulin analogs aspart and lispro have clinical trials that prove they are safe in pregnancy. To date there are not clinical trials in pregnancy for the long acting insulin detemir and glargine. The basal insulin needs to be given either with a continuous infusion pump or as three doses of NPH spaced 8 hours apart.

High risk patients should also schedule weekly visits with their obstetrician, ensure co-management occurs with their endocrinologist, and schedule early ultrasound scans to establish dates. The upper level ultrasound scan should be conducted at 20-22 weeks gestation with fetal echocardiogram, growth scan at 4 weeks and scans for EFW as indicated. Antepartum surveillance should begin at 34 weeks and include biweekly NSTS and weekly AFIs. Earlier testing will be indicated by associated maternal and fetal conditions. Delivery should occur no later than 40 weeks. An earlier delivery should be considered if pulmonary maternity is established or maternal or fetal indications are present. If induction or scheduled Cesarian Section is needed, patients should take bedtime insulin the night before admission, fast in the morning, and do not take insulin the morning of admission.

Prevention

The days of the four basic food groups - dairy, meat, vegetables and fruit - are long gone. Today, a healthy diet encompasses a far wider range of options and includes whole grains, legumes, seeds and nuts, fish and even plant oils such as olive oil. Add in ethnic, religious, cultural and personal preferences and there are more options than ever before when planning healthy meals and snacks.

A Healthy Eating Plan.  A healthy eating plan can be illustrated in many ways, but guidelines for choosing foods are widely represented in various food pyramids. These pyramids reflect the general principles of healthy eating but allow for different food choices.  The triangular shape of the pyramid helps to focus on selecting healthy foods. Most foods should be chosen from the lower half of the pyramid, and foods to eat in smaller amounts or less frequently are shown farther up the pyramid. A pyramid familiar to most Americans is the Food Guide Pyramid, established by the United States Department of Agriculture (USDA) and the Department of Health and Human Services in 1992. The Food Guide Pyramid has since been replaced with MyPyramid, a new symbol and interactive food guidance system that provides a more personalized eating plan based upon age, gender and daily physical activity.  Many other pyramids exist, and include the Asian, Latin American and Mediterranean diet pyramids, the Mayo Clinic Healthy Weight Pyramid, and the Vegetarian Diet Pyramid.

Food Pyramids.   

The lower number of servings in each food group is based on 1,200 calories and the higher number is based on 2,000 calories. If you exercise regularly and aren't overweight, you may need more calories.

Diet Planning.  Here are a few simple practices for a healthy diet plan.

• Choose a variety of foods from each major food group to ensure intake of adequate amounts of calories, protein, vitamins, minerals and fiber. Choosing a wide range of foods also helps to make meals and snacks more interesting.
• Adapt the meal plan to meet specific tastes and preferences. For example, a serving of grains doesn't only mean a slice of wheat bread. It can be wild rice, whole-wheat pasta, grits, bulgur, cornmeal muffins or even popcorn.
• Combine foods from different major groups. For example, create a meal of (1) tortillas (grain group) and beans (meat and beans group), or (2) fish topped with fruit salsa served with steamed vegetables over pasta.
• Select meals and snacks wisely and chose nutrient-rich foods within each group. For example, in the setting of lactose intolerance, choose foods from other groups that are good sources of the nutrients found in dairy products.

Treatment

When Sugar Management Goes Away. Digestible carbohydrates are broken down in the intestine into their simplest form, sugar, which then enters the bloodstream as glucose. Insulin is a hormone secreted from the pancreas in response to the rising blood glucose, and helps lower blood glucose by depositing it into body cells for energy or storage. In some people, this cycle doesn't work properly. People with type-1 diabetes do not make enough insulin to respond to the rising blood glucose. Individuals with type-2 diabetes have tissue cell insulin resistance, which prevents lowering of the blood glucose. Genetic makeup, a sedentary lifestyle, being overweight, and eating an unhealthy diet can all promote insulin resistance. Data from the Insulin Resistance Atherosclerosis Study suggests that substituting whole grains for refined grains in the diet can improve insulin sensitivity.

Carbohydrates and the Glycemic Index. The glycemic index, measures how fast and how high blood sugar rises after eating food that contains carbohydrates. White bread, for example, is digested almost immediately to sugar and causes the blood glucose to rise rapidly, and thus is classified as having a high glycemic index. Brown rice is digested more slowly to sugar, has a low glycemic index, and results in a lower and more sustained rise in blood glucose. Diets rich in high-glycemic-index foods have been linked to an increased risk for both diabetes and heart disease. Conversely, lower glycemic index foods have been shown to help control type-2 diabetes.

• High glycemic index foods include sugar, potatoes, and refined foods such as white bread, white rice, white spaghetti and cereals (i.e., Corn Flakes, Cheerios).
• Low glycemic index foods include legumes, whole fruits, oats, bran, and whole-grain cereals.

One of the most important factors that determine a food's glycemic index is how highly processed its carbohydrates are. Processing carbohydrates removes the fiber-rich outer bran and the vitamin-rich and mineral-rich inner germ, leaving mostly the starchy endosperm. Finely ground grain is more rapidly digested, and has a higher glycemic index than coarsely ground grain. Other factors that influence how quickly the carbohydrates in food are digested, release sugar and raise glucose include:

• Fiber content. Fiber protects the starchy carbohydrates in food from rapid digestion, slowing the release of carbohydrate sugar molecules into the bloodstream.
• Ripeness. Ripe fruits and vegetables tend to have more sugar than unripe ones, and therefore tend to have a higher glycemic index.
• Type of starch. Starch comes in many different (linear and branched) forms, and some release sugar molecules more easily than others. The starch in potatoes, for example, is digested and absorbed into the bloodstream relatively quickly.
• Fat and acid content. The more fat or acid a food contains, the slower its carbohydrates are converted to sugar and absorbed into the bloodstream.

There is one important item that is not disclosed in a food's glycemic index: the relative amount of carbohydrate in a given food. For example; watermelon is a sweet-tasting fruit with a high glycemic index. However, a slice of watermelon has only a small amount of carbohydrate per serving and (as the name suggests) is made up mostly of water. Thus, the glycemic index alone may not tell us everything about a food's impact on blood sugar (glucose) levels. A new classification of food, called the glycemic load, takes into account both the amount of carbohydrate in the food and the impact that carbohydrate has on the blood glucose level. A food's glycemic load is determined by multiplying its glycemic index by the amount of carbohydrate it contains. Although seemingly complicated, the basic message is simple: whenever possible, replace highly processed grains, cereals and sugars with minimally processed whole-grain products.

Health Effects of Eating Fiber.  Fiber appears to reduce the risk of developing various conditions, including heart disease, diabetes, colon diverticular disease and constipation. However, fiber may have little, if any, effect on preventing colon cancer.

Fiber and colon cancer. Well designed studies have failed to show a link between fiber and prevention of colon cancer. One of these - a Harvard study - followed over 80,000 female nurses for 16 years and found that dietary fiber was not strongly associated with a reduced risk for either colon cancer or colon polyps (a precursor to colon cancer).

Fiber and heart disease. Dietary fiber intake has been linked to a lower risk of heart disease in a number of large studies. In one study - a Harvard study of over 40,000 male health professionals - a high total dietary fiber intake was associated with a 40% lower risk of coronary heart disease. Cereal fiber seemed particularly beneficial. A related Harvard study of female nurses produced similar findings.

Fiber and type 2 diabetes. Type 2 diabetes is the most common form of diabetes. It is characterized by sustained high blood sugar (glucose) levels and resistance to the effects of insulin to lower glucose. Harvard studies of male health professionals and female nurses both found that a diet low in cereal fiber and rich in high glycemic index foods more than doubled the risk of type 2 diabetes compared to a diet high in cereal fiber and low in high glycemic index foods. Fiber intake has also been linked with the metabolic syndrome, a constellation of factors that increases the chances of developing heart disease and diabetes. Factors of the metabolic syndrome include high blood pressure, high insulin levels and elevated blood glucose, excess weight (especially around the abdomen), high levels of triglycerides and low levels of HDL cholesterol. Several studies suggest that consuming a higher intake of fiber may help prevent metabolic syndrome and the risk for diabetes.

Fiber and diverticular disease. Diverticulitis is an inflammation of the intestine and is one of the most common age-related disorders of the colon. In North America, this painful disease is estimated to occur in one-third of individuals over age 45 and in two-thirds of those over age 85. Among male health professionals in a long-term follow-up study, eating dietary fiber, particularly insoluble fiber, was associated with about a 40% lower risk of diverticular disease.

Fruits, Vegetables, and Health.  There is compelling evidence that a diet rich in fruits and vegetables can lower blood pressure and cholesterol, and decrease the risk of heart disease and stroke. There is also data to suggest that eating fruits and vegetables likely provides protection against certain types of cancer.

Fruits and Vegetables and Cardiovascular Disease. The largest and longest study to date, done as part of the Harvard-based Nurses' Health Study and Health Professionals Follow-up Study, found that the higher the average daily intake of fruits and vegetables, the lower the chances of developing cardiovascular disease. This study included almost 110,000 men and women whose health and dietary habits were followed for 14 years. Compared with those in the lowest category of fruit and vegetable intake (< 1.5 servings a day), those who averaged > 8 servings a day were 30% less likely to have had a heart attack or stroke.  

Fruits and Vegetables, Blood Pressure and Cholesterol. Hypertension is a primary risk factor for developing heart disease or stroke. One of the most convincing associations between diet therapy and lower blood pressure was found in the Dietary Approaches to Stop Hypertension (DASH) study. The study diet was rich in fruits, vegetables and low-fat dairy products and also restricted the amount of saturated and total fat consumed. The upper (systolic) blood pressure fell by about 11 mm Hg and the (lower) diastolic blood pressure declined by almost 6 mm Hg with diet therapy; decreases similar to that achieved by medications.

In the National Heart, Lung, and Blood Institute's Family Heart Study of 4,466 men and women, those with the highest consumption (> 4 servings/day) of fruits and vegetables had significantly lower levels of LDL cholesterol. Eating more fruits and vegetables can help lower cholesterol, but how this occurs is still unknown. It is possible that eating more fruits and vegetables (1) results in eating less meat and dairy products, and thus less cholesterol and saturated fat, and (2) soluble fiber in fruits and vegetables may help block the absorption of cholesterol ingested.

Fruits and Vegetables and Cancer. Numerous early case-control studies revealed what appeared to be a strong link between eating fruits and vegetables and protection against cancer. However, it is possible that these results may have been skewed by problems such as recall bias and selection bias. Data from cohort studies that follow large groups of initially healthy individuals for many years have not consistently shown that diets rich in fruits and vegetables prevents cancer. For example, the 14-year Nurses' Health Study and Health Professionals Follow-up Study reported men and women with the highest intake of fruits and vegetables (> 8 servings/day) were just as likely to have developed cancer as those who ate only 1.5 servings daily.

It may be possible that fruits and vegetables protect against certain types of cancer. The International Agency for Research on Cancer, of the World Health Organization, recently reported that there is limited evidence for a cancer-preventive effect of total consumption of fruit and vegetables for cancers of the mouth and pharynx, esophagus, stomach, colon-rectum, larynx, lung, ovary, bladder and kidney. The International Agency for Research on Cancer acknowledges that specific fruits and vegetables may also protect against certain types of cancer. For example, lycopene (red pigment) in tomatoes may help protect men against prostate cancer (Health Professionals Follow-up Study).

Supplements.  Are dietary supplements necessary in otherwise healthy adults? The answer depends on eating patterns, lifestyle habits, and other factors such as age. A standard multivitamin supplement doesn't come close to making up for an unhealthy diet. A multivitamin provides a dozen or so of the vitamins known to maintain health, a mere shadow of what's available from eating a healthy diet. However, there's good evidence that taking a daily multi-purpose vitamin may be reasonable even in otherwise healthy adults. A standard multivitamin can ensure the Recommended Daily Intake (RDI) of vitamins and minerals needed for health. Vitamin supplementation should not exceed more than 100% of the RDI value.  Dietary supplements may be appropriate if any of the following exist:

• Poor dietary habits. Many people don't receive all of the nutrients they need from their diet because they either cannot (or do not) eat enough, or an adequate variety, of healthy foods. Eating less than five total servings of fruits and vegetables daily may not provide all of the vitamins and minerals the body needs. Also, eating only once or twice a day may limit the number and variety of servings from the various food groups.
• Consuming less than 1,200 calories a day. Low-calorie diets limit the types and amounts of foods, and nutrients, consumed. Unless monitored by a doctor, a low-calorie diet isn't usually recommended.
• Vegetarian diets. Vegetarians may not consume enough calcium, iron, zinc, vitamin B-12 or vitamin D. However, these nutrients are naturally present in non-meat sources, such as fortified soy products, green leafy vegetables, legumes, whole-grain products and nuts.
• Medical conditions affecting nutrient absorption. Food allergies or intolerance (such as protein or dairy products) may limit nutrient intake. Diseases of the liver, gallbladder, intestines or pancreas may cause malabsorption or maldigestion of nutrients.
• Postmenopausal women. After menopause, women are at an increased risk of bone loss due to estrogen deficiency. Postmenopausal women should ingest 1000-1500 milligrams elemental calcium in divided doses daily. Vitamin D guidelines are 400 international units (IU) for young postmenopausal women, 600 IU for women over 70 years, and 800 IU in the setting of osteoporosis.
• Heavy menstrual bleeding. Additional iron may be needed to treat anemia and replace iron depleted by blood loss.
• Pregnancy. Requirements for calcium, folate and iron all increase during pregnancy. Folate is needed very early in pregnancy to help protect the baby against neural tube birth defects, such as incomplete closure of the spine (spina bifida). Iron can help prevent fatigue by treating iron deficiency anemia. The National Academy of Sciences recommends 1000 mg/day elemental calcium for women 19-50 years and lactating women.  It's important to take these supplements during planning of pregnancy, before becoming pregnant.
• Smoking. Tobacco decreases the absorption of many vitamins and minerals, including vitamin C, folate, magnesium and calcium. Dietary supplements won't make up for the major health risks caused by smoking, and it is safest to avoid all tobacco products.
• Excessive alcohol intake. Long-term excessive alcohol intake, as a substitute for food calories, may result in a diet lacking in essential nutrients. Excessive drinking is defined as more than two drinks a day for men and more than one drink a day for women. Taking dietary supplements will not make up for the major health risks caused by excessive alcohol consumption.

Choosing and using supplements. There are upper limits for intake of vitamins and minerals, and more is definitely not always better.  Randomized trials of vitamin C, vitamin E, and beta-carotene have not revealed much in the way of protection from heart disease, cancer or age-related eye diseases. In addition, over consumption of one vitamin has the potential to mask a deficiency of another. For instance, (1) if excess folic acid is taken, it can mask a vitamin B12 deficiency, and (2) excess zinc supplementation can lead to a deficiency in copper and can cause problems with red or white blood cell production. When taking a vitamin or mineral supplement, consider these factors:

• Look for “USP” on the label. This ensures that the supplement meets the standards for strength, purity, disintegration and dissolution established by the testing organization U.S. Pharmacopeia (USP).
• Read labels carefully. Product labels list the serving size, and the active ingredients and nutrients per serving (for example, capsule, packet or teaspoonful).
• Avoid supplements that provide “megadoses” of individual vitamins or minerals.  In general, choose a brand name multivitamin-mineral supplement (i.e., Centrum, One-A-Day, or others) that provides about 100% of the Daily Value (DV) of all the vitamins and minerals. The exception to this is calcium as most calcium-containing vitamin supplements don't provide 100% of the DV for calcium.

Beware of gimmicks. Synthetic vitamins are usually the same as so-called "natural" vitamins, but "natural" vitamins usually cost more. Added herbs, enzymes or amino acids mostly add only cost, and some herbs can interact negatively with certain prescribed medications.

References
http://mayoclinic.com/health/HealthyLivingIndex/HealthyLivingIndex/ (mayo clinic web site)
http://www.hsph.harvard.edu/nutritionsource/index.html (harvard school of public health web site)
http://www.glycemicindex.com (glycemic index web site)
http://mypyamid.gov (government pyramid web site)   
http://nccam.nih.gov (national center for complementary and alternative medicine)