Fruit and Vegetable Intake and Prevention of Chronic Disease

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Fruits and vegetables are nutrient-dense foods, meaning they provide high nutrients, with lower energy (kilocalories). Fruits and vegetables also are low in fat and sodium, yet high in fiber and potassium. Higher intakes of potassium have been shown to decrease hypertension. In addition, fruits and vegetables are excellent sources of vitamins and minerals, including vitamin A, vitamin C, folate, iron, calcium, magnesium, and manganese, to name a few (¹).

It has been well-established that increased fruit and vegetable intake, because of their high nutrient content, prevent certain chronic diseases. Boeing et al. (²) conducted a critical review of the literature to evaluate the effect of fruit and vegetable consumption on chronic disease prevention. The researchers evaluated the effects of fruit and vegetable consumption on the following diseases: obesity, type 2 diabetes mellitus, coronary heart disease, cerebrovascular accident (stroke), hypertension, various cancers, chronic obstructive pulmonary disease, asthma, chronic inflammatory bowel disease, rheumatoid arthritis, osteoporosis, eye diseases, and dementia.

Boeing et al. (²) reported that there was compelling evidence that increased consumption of fruits and vegetables reduces the risk for coronary heart disease, stroke, and hypertension. They reported “probable evidence” that increased fruit and vegetable intake reduces the risk of cancer (generally). They also reported that there is “possible evidence” that increased fruit and vegetable intake results in prevention of weight gain, which, in turn, may reduce the risk of type 2 diabetes mellitus (because overweight and obesity are related to increased risk of type 2 diabetes mellitus). Boeing et al. (²) also reported that there is “possible evidence” that increased intake of fruits and vegetables would decrease the risk of chronic obstructive pulmonary disease, asthma, rheumatoid arthritis, osteoporosis, certain eye diseases, and dementia.

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However, the researchers stated that there was “insufficient evidence” of fruit and vegetable intake on the prevention of chronic inflammatory bowel disease, glaucoma, and diabetic retinopathy. Despite lower evidence of increased fruit and vegetable intake benefits with respect to some diseases, the increased consumption of these nutrient-dense foods needs to be encouraged, because of their positive effects on the prevention of numerous chronic conditions and disease states. In addition, increasing fruit and vegetable intake results in greater vitamin, mineral, antioxidant, and fiber intake, as well as increased variety in food intake.

Ribeiro et al. (³) conducted a longitudinal study to evaluate fruit and vegetable intake and physical activity on disability in 432 late middle-aged African Americans. With respect to fruit and vegetable intake, they reported that the consumption of fruits and vegetables, other than carrots, potatoes, or salads, was associated with better hand grip strength and less frailty. Conversely, fruit juice intake was associated with worse hand grip strength and increased frailty. They also reported that leisurely walking was associated with favorable health outcomes.

In a study conducted in Ecuador, Ochoa-Avilés et al. (⁴) assessed the effect of a school-based intervention that focused on dietary intake and physical activity. They evaluated dietary intake, physical activity, body mass index, waist circumference, and blood pressure in 1,046 adolescents, 12 to 14 years of age, representing 20 schools in Ecuador.

Compared with the control schools, adolescents in the intervention schools decreased their intake of unhealthy snacks and added sugar. Unfortunately, they reported a decrease in fruit and vegetable intake in both the intervention and control schools; however, the decrease was less in the intervention group. They also reported a lower waist circumference in the intervention group. Although there were no improvements in fruit and vegetable intake, there was a decrease in the consumption of unhealthy snacks. Ochoa-Avilés et al. (⁴) stated that, “The program strategies must be implemented at the national level through collaboration between the academia and policy makers to assure impact on a larger scale.”

FRUIT AND VEGETABLE INTAKE IN THOSE IN THE MILITARY AND ATHLETES

The health of soldiers is an important factor that influences their ability to perform difficult and physically demanding tasks. Jayne et al. (⁵) evaluated the nutrition knowledge, eating identity type, and food choice behaviors in 575 drill sergeant candidates in the U.S. Army. The food choice behavior analysis included questions about the drill sergeants’ frequency of eating out, fruit and vegetable intake, and their frequency of skipping meals. They reported that a healthy eating identity was significantly associated with greater fruit and vegetable intake and negatively associated with the regularity of eating out and the occurrence of skipping meals. They also reported that the greater the nutrition knowledge, the less likely meals would be skipped. Jayne et al. (⁵) emphasized that encouraging drill sergeants to develop a healthy eating identity may be more beneficial than nutrition education.

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Fruits and vegetables provide dietary nitrate (nitrate can lead to increased vasodilation and blood flow, and hence, to improved exercise performance). Most research on nitrate intake has been conducted using beetroots or beetroot juice. Jonvik et al. (⁶) evaluated habitual dietary nitrate intake in 226 female and 327 male highly trained Dutch athletes. They reported that most of the dietary nitrate intake of these athletes was consumed through vegetables (spinach and lettuce contributed to 74% of the total nitrate intake), potatoes, and fruit. Female athletes consumed more dietary nitrates compared with male athletes.

Porcelli et al. (⁷) examined whether a high nitrate diet improved exercise performance. They conducted a randomized, cross-over design trial, where seven healthy men were measured six days after a high nitrate diet or six days after a control diet (8.2 vs. 2.9 mmol/d of dietary nitrate, respectively). The researchers reported that, during the high nitrate diet, there was a significant decrease in oxygen consumption during moderate-intensity cycling exercise compared with the control diet. In addition, they reported a significantly higher muscle effort during sub-maximal isometric knee extension, when the athletes were consuming the high nitrate diet. Porcelli et al. (⁷) also reported an improvement in repeated sprint testing during the high nitrate diet period. Teaching athletes that dietary nitrate can be obtained from a variety of fruits and vegetables may encourage them to consume a more varied diet and lead to improved exercise performance.

SUMMARY

We have been told to consume more fruits and vegetables since we were children. In addition, there is strong evidence that increased fruit and vegetable intake can prevent some chronic diseases and enhance exercise performance. In addition to enhancing food variety, increased fruit and vegetable intake will lead to greater consumption of a variety of vitamins and minerals. Consuming five servings of fruits and vegetables per day is better than any vitamin or mineral supplement!