Asthma

Vitamin C, present in fruits, is a powerful antioxidant and anti-inflammatory agent. Its anti-inflammatory activity may decrease the incidence of asthma symptoms. A large preliminary study has shown that young children with asthma experience significantly less wheezing if they eat a diet high in fruits rich in vitamin C.

Atherosclerosis

A diet high in fiber prevents coronary heart disease. Eating fruits high in the soluble fiber pectin has also been linked with reduced cholesterol levels, which protects against atherosclerosis.

Athletic performance

Carbohydrates are the most efficient fuel for energy production and can also be stored as glycogen in muscle and liver, functioning as a readily available energy source for prolonged, strenuous exercise. For these reasons, carbohydrates may be the most important nutrient for sports performance. Depending on training intensity and duration, athletes require up to 4.5 grams of carbohydrates per day per pound of body weight or 60–70% of total dietary calories from carbohydrates, whichever is greater. Emphasizing intake of fruits and other high-quality carbohydrates while reducing intake of fatty foods may be beneficial for athletic performance.

Bronchitis

A diet high in antioxidants may protect against the free-radical-damaging effect of environmental toxins or cigarette smoke. Studies comparing different populations have shown that increasing fruit consumption may reduce the risk of developing chronic bronchitis.

Bruising

Many Americans eat insufficient amounts of foods containing vitamin C; the disease caused by vitamin C deficiency, scurvy, causes easy bruising. While very few people actually have scurvy, even minor deficiencies of vitamin C can increase bruising. People who experience easy bruising may want to try eating more fruits—common dietary sources of vitamin C. The diet can be assessed by doctors by using a diet diary, sometimes accompanied by computerized diet analysis. A diet diary is a written record of what and how much a person is eating, usually divided into sections by meal and/or day. As used by many doctors, diet diaries lasting one week are most common. If such an analysis reveals a lack of dietary vitamin C and flavonoids (related compounds present in most fruit), the diet requires more fruits and vegetables to correct the problem.

Cancer

Consumption of fruits is widely accepted as lowering the risk of most common cancers except prostate cancer. A meta-analysis of studies on breast cancer risk and diet found that high consumption of fruit was associated with a 6% reduction of breast cancer compared to low consumption in 12 studies. Many doctors recommend that people wishing to reduce their risk of cancer eat several pieces of fruit and several portions of vegetables every day. Optimal intakes remain unknown.

Capillary Fragility

Eating plenty of fruit will provide more of the nutrients mentioned in the following paragraph that support the structure of capillaries.

Patients undergoing dialysis may develop low levels of vitamin C, which can lead to capillary fragility. As little as 100 mg per day may help people with artificially induced fragility, an amount that can be obtained by eating several pieces of fruit per day. For others, higher amounts may be necessary (1 gram or more), which requires vitamin C supplementation. Widespread plant compounds called flavonoids help strengthen weakened capillaries. In test tube and animal studies, they have been shown to protect collagen, one of the most important components of capillary walls. Flavonoids are abundant in fruits, although increasing fruit consumption alone may not be sufficient to prevent or reverse capillary fragility. Studies showing a benefit to capillary integrity from flavonoids have used dietary flavonoid supplements.

Cardiovascular disease

A diet high in fruits appears protective against heart disease. The total number of deaths from cardiovascular disease was significantly lower among men with high fruit consumption in one preliminary study. A large study of male healthcare professionals found that those men eating mostly a “prudent” diet (high in fruits, vegetables, legumes, whole grains, fish, and poultry) had a 30% lower risk of heart attacks compared to men who ate the fewest foods in the “prudent” category. A parallel study of female healthcare professionals showed a 15% reduction in cardiovascular risk when they ate a diet high in fruits and vegetables compared to the effect of a low fruit and vegetable diet.

Cataracts

People with low blood levels of antioxidants and those who eat few antioxidant-rich fruits and vegetables have been reported to be at high risk for cataracts.

Some but not all studies have reported that eating more fruits and vegetables rich in beta-carotene was associated with a lower risk of cataracts. It remains unclear whether natural beta-carotene from food or supplements would protect the eye or whether beta-carotene in food is merely a marker for other protective factors in fruits and vegetables high in beta-carotene.

Chronic candidiasis

Based on their clinical experience and on very preliminary research, several doctors have suggested that a number of dietary factors may promote the overgrowth of Candida. Dried fruits, which are high in sugar, have been blamed for contributing to promotion of Candida overgrowth. However, few clinical trials have investigated whether such dietary factors affect people with conditions for which Candida albicans is the causative agent.

Congestive heart failure (CHF)

Whole fruit and fruit and vegetable juice, which are high in potassium, are recommended by some doctors for CHF; however, this dietary change should be discussed with a healthcare provider, because several drugs given to people with CHF can actually cause retention of potassium, making dietary potassium, even from fruit, dangerous. Bananas are a rich source of potassium and need to be avoided in persons taking potassium-sparing diuretics.

Crohn’s disease

In one trial, patients (rather than doctors) were asked which foods aggravated Crohn’s disease symptoms. Those without ileostomies said that raw fruit and tomatoes were among the most problematic foods, though responses varied from person to person, and other reports have come up with different lists. People with Crohn’s disease wishing to identify and avoid potential problem foods should consult a doctor.

Diabetes

Eating carbohydrate-containing foods, including some fruits, temporarily raises blood sugar and insulin levels. On the other hand, a diet rich in the soluble fiber found in fruit may lower the risk of type 2 diabetes, despite the high carbohydrate content of most fruit.

High-fiber supplements, such as pectin from fruit, have improved glucose tolerance in some studies. A review of the research revealed that the extent to which moderate amounts of fiber help people with diabetes in the long term is still unknown, and the lack of many long-term studies has led some researchers to question the importance of fiber in improving diabetes. Nonetheless, most doctors advise people with diabetes to eat a diet high in fiber. Focus should be placed on fruits, vegetables, seeds, oats, and whole-grain products.

Eczema

Eczema can be triggered by allergies. Most children with eczema have food allergies, according to data from double-blind research. A doctor should be consulted to determine if allergies are a factor. Once the trigger for the allergy has been identified, avoidance of the allergen can lead to significant improvement. However, classical food allergens are often not the cause of eczema in adults. A variety of substances have been shown, in a controlled trial, to trigger eczema reactions in susceptible individuals; avoidance of these substances, such as aromatic compounds found in fruits, has similarly been shown to improve eczema. These reactions do not represent true food allergies, but are instead a type of food sensitivity reaction. The authors of this study did not identify which substances are the most common triggers of the condition.

Heart attack

A high-fiber diet, particularly one that is high in water-soluble fiber (such as fruit), is associated with decreased risk of both fatal and nonfatal heart attacks, probably because presence of such fiber is known to lower cholesterol. In a preliminary study, the total number of deaths from cardiovascular disease was found to be significantly lower among men with high fruit consumption.

Making positive dietary changes immediately following a heart attack is likely to decrease one’s chance of having a second heart attack. In one study, individuals began eating more vegetables and fruits, and substituted fish, nuts, and legumes for meat and eggs 24 to 48 hours after a heart attack. Six weeks later, the diet group had significantly fewer fatal and nonfatal heart attacks than a similar group that did not make these dietary changes. This trend continued for an additional six weeks.

High cholesterol

Soluble fiber from fruit pectin has lowered cholesterol levels in most trials. Doctors often recommend that people with elevated cholesterol eat more foods high in soluble fiber.

High homocysteine

A controlled trial showed that eating a diet high in fruits and vegetables containing folic acid, beta-carotene, and vitamin C effectively lowered homocysteine levels. Healthy people were assigned to either a diet containing a pound (454 grams) of fruits and vegetables per day, or to a diet containing three and a half ounces (100g) of fruits and vegetables per day. After four weeks, those eating the higher amount of fruits and vegetables had an 11% lower homocysteine level compared to those eating the lower amount of fruits and vegetables.

High triglycerides

There is evidence that ingesting fructose in amounts that are found in a typical Western diet can raise TG levels, although not all studies agree on that point. It should be noted that most studies of fructose investigated the refined form, not the fructose that occurs naturally in some fruits.

Diets high in fiber have reduced TG levels in several clinical trials, but have had no effect in other clinical trials. Water-soluble fibers, such as the pectin found in fruit, may be particularly helpful in lowering triglycerides.

Hypertension

As with conventional drugs, the use of natural substances sometimes controls blood pressure if they are taken consistently, but does not lead to a cure for high blood pressure. Thus, someone whose blood pressure is successfully reduced by weight loss, avoidance of salt, and increased intake of fruits and vegetables would need to maintain these changes permanently in order to maintain control of blood pressure. Left untreated, hypertension significantly increases the risk of stroke and heart disease.

Vegetarians have lower blood pressure than do people who eat meat. This occurs partly because fruits and vegetables contain potassium—a known blood pressure–lowering mineral. The best way to supplement potassium is with fruit, which contains more of the mineral than do potassium supplements. However, fruit contains so much potassium that people taking potassium-sparing diuretics can consume too much potassium simply by eating several pieces of fruit per day. Therefore, people taking potassium-sparing diuretics should consult the prescribing doctor before increasing fruit intake. In the Dietary Approaches to Stop Hypertension (DASH) trial, increasing intake of fruits and vegetables (and therefore fiber) and reducing cholesterol and dairy fat led to large reductions in blood pressure in just eight weeks.

Hypoglycemia

Doctors find that individuals with hypoglycemia usually improve when they eliminate refined sugars and alcohol from their diet; eat foods high in fiber (such as fruit); and eat small, frequent meals. Few studies have investigated the effects of these changes, but the research that is available generally supports the observations of doctors.

Indigestion

Citrus fruits may aggravate indigestion in some individuals. Medical doctors often recommend that people with indigestion avoid citrus fruits and other potentially irritating foods.

Insulin resistance syndrome (IRS)

A recent preliminary study suggested that a healthy, balanced diet low in fried foods and sausages, and high in fruits, vegetables, fish, and complex carbohydrates (such as brown rice and whole wheat pasta) was associated with protection from many aspects of IRS.

Irritable bowel syndrome (IBS)

The conventional treatment for IBS includes limiting the intake of fructose. Fructose is found in concentrated amounts in dried fruit and fruit juice. Preliminary evidence suggests that some people with IBS have greater trouble absorbing fructose (as found in high concentration in fruit juice and dried fruit). In this report, restricting intake of fructose and lactose (as found in milk) led to reduction in symptoms in 40% of people with IBS symptoms. Therefore, when attempting to uncover food sensitivities, people with IBS should consider the possibility that fruit juice and dried fruit might trigger symptoms.

Kidney stones

Potassium reduces urinary calcium excretion, and people who eat high amounts of dietary potassium appear to be at low risk of forming kidney stones. Most kidney stone research involving potassium uses the form of the element called potassium citrate. However, increasing dietary potassium may reduce the risk of kidney stone recurrence. The best way to increase potassium is to eat fruits and vegetables. The level of potassium in food is much higher than the small amounts found in supplements.

Macular degeneration

Eating a diet rich in fruits and vegetables raises blood levels of antioxidants. People with high blood levels of antioxidants have a lower risk of macular degeneration. Those with the highest levels (top 20th percentile) of the antioxidants selenium, vitamin C, and vitamin E may have a 70% lower risk of developing macular degeneration, compared with individuals with the lowest levels of these nutrients (bottom 20th percentile). People who eat fruits and vegetables high in beta-carotene, an antioxidant, are also at low risk. However, a preliminary study found no association between age-related macular degeneration and intake of antioxidants, either from the diet, from supplements, or from both combined.

Measles

Flavonoids are a nutrient found in the white, pithy parts of fruits and vegetables. In preliminary laboratory research, certain flavonoids have been found to inhibit the infectivity of measles virus in the test tube. Whether eating fruits high in flavonoids could be effective in preventing or treating measles is unknown.

Night blindness

Night blindness can be an early sign of vitamin A deficiency. Low intake of fruits and vegetables containing beta-carotene, which the body can convert into vitamin A, may contribute to a vitamin A deficiency. However, beta-carotene is less effective at correcting vitamin A deficiency than is vitamin A itself, as it is less well absorbed and is only slowly converted by the body into vitamin A.

Pap smear

Most dietary studies have found that women receiving high amounts of nutrients from fruits and vegetables have less risk of cervical dysplasia.

High blood levels of folate (the food form of folic acid) have been linked to protection against the development of cervical dysplasia. However, the high folate in the diet may only be a marker for eating more fruits and vegetables.

Parasites

When traveling in less-developed countries, people should avoid eating fruits that cannot be peeled. They are potential sources of parasitic infection.

PMS

Several studies suggest that diets low in fat or high in fiber may help to reduce symptoms of PMS. Many doctors recommend diets very low in meat and dairy fat and high in fruit, vegetables, and whole grains.

Pregnancy

A well-balanced and varied diet that includes fresh fruits and vegetables is a good way for pregnant women to avoid nutrient deficiencies.

Retinopathy

Animal studies suggest that dietary fructose may contribute to the development of retinopathy. Although such an association has not been demonstrated in humans, some doctors advise their diabetic patients to avoid foods containing added fructose or high-fructose corn syrup. On the other hand, the fructose that occurs naturally in some fruits has not been found to be harmful.

Stroke

Diets high in fruit and/or vegetables are associated with a reduced risk of stroke, according to most studies. In a large preliminary study, consumption of citrus fruit and juice conferred a high degree of protection. The protective effect of fruit and fruit juices may result from a variety of components found in these foods, including potassium, vitamin C, and beta-carotene, according to most, but not all, research. Flavonoids found in fruit and vegetables have also been inconsistently associated with decreased stroke risk. Because the effects of specific components in produce responsible for the protective effect against stroke remain poorly understood, people should rely primarily on eating more fruits and vegetables themselves rather than taking supplements in order to achieve lower stroke risk.

Researchers have found an association between diets low in potassium and increased risk of stroke. People who take potassium supplements have been reported to have a low risk of suffering a stroke. However, the association of increasing dietary potassium intake and decreasing stroke mortality only occurred in black men and hypertensive men in one study. Others have found an association between increased risk of stroke and the combination of low dietary potassium plus high salt intake. Increasing dietary potassium has lowered blood pressure in humans, which by itself should reduce the risk of stroke; however, some of the protective effect of potassium appears to extend beyond its ability to lower blood pressure. Maintaining a high potassium intake is best achieved by eating fruits and vegetables.

Vaginitis

Many doctors advise women who have a yeast infection (or are predisposed to such infections) to limit their intake of fruit juices and other sources of refined carbohydrates. For persistent or recurrent infections, some doctors recommend that fruit also be avoided.