Importance of Fruits and Vegetables in Human Diet

Fruits and vegetables are important sources of micronutrients including vitamin C, vitamin A, thiamine, niacin, folate, minerals and dietary fibre. They can also provide antioxidants.

Aiming for nine total servings of fruits and veggies per day might seem unrealistic, but five is a good place to start. Here are the health benefits you can expect if you hit that goal:.

Vitamins

There is a huge variety of fruit and vegetables that provide the body with important vitamins and minerals. These nutrients are essential to human health, and many diseases can be prevented if people get enough fruits and vegetables. The human body needs vitamin A, C, E and K, thiamin, folate, calcium, iron, magnesium, potassium, sodium, and zinc.

In addition to vitamins, fruits and vegetables also contain antioxidants, which can prevent damage to cells. These nutrients are crucial to the human diet, and it is recommended that adults consume at least 400g of fruits and vegetables per day, or five servings.

The distinction between fruits and vegetables is a tricky one, and largely depends on whether one is thinking like a botanist or a chef. For example, tomatoes are botanically a fruit, but most of us would consider them a vegetable, because they do not have the same sweet taste as other fruits. Similarly, butternut squash is a vegetable but most of us would call it a fruit because it makes a good pie. Despite the confusion, fruits and vegetables are an important part of any healthy diet.

Minerals

Minerals are naturally-occurring chemical elements that form the basis of plant growth. They are passed down from stone, rocks and particulate through erosion to the soil and then absorbed by plants. Herbs, roots and some fruits are also rich in minerals.

Our bodies need two kinds of minerals: the major ones and the trace minerals. We need the major ones, like calcium, phosphorus, magnesium, sodium, potassium and sulfur, in larger amounts (100 milligrams or more a day). We need the trace minerals, including iron, iodine, zinc, copper, chromium and selenium, in smaller amounts.

Fruits and vegetables are low in fat and calories, yet provide a high amount of vitamins, minerals and dietary fibre. They are important contributors to a healthy diet and should be consumed regularly. The Food and Agriculture Organisation and the World Health Organization recommend adults consume at least five servings of fruit and vegetables a day excluding starchy vegetables. However, many people do not meet these recommendations. High levels of food loss and waste, and the need to manage pests and diseases, can limit accessibility, and production requires substantial inputs of water, energy and chemicals.

Carbohydrates

Carbohydrates are an important source of energy for the body. They provide fuel for the central nervous system and help to sustain working muscles, according to the NHS. Carbohydrates also help to spare protein from being used for energy, and are necessary for lipid (fat) metabolism.

The body breaks carbohydrates down into small sugar molecules that the cells can absorb, called monosaccharides. Monosaccharides are absorbed and transported to the liver, where they are converted to glucose for use as energy. Carbohydrates that contain two sugar molecules are called disaccharides, and examples of this include sucrose (table sugar), lactose and maltose.

Carbohydrates in foods that are naturally occurring, such as fruit and vegetables, are better for you than those that are processed or refined, which have little to no nutritional value. Refined sugars, often known as “empty calories,” are found in many products such as sweetened beverages, candy, cookies and pastries. They cause high spikes in blood sugar and can contribute to weight gain over time. Carbohydrates in whole fruits and vegetables, on the other hand, are slowly absorbed into the blood stream, resulting in a more steady supply of energy over time.

Fibre

The fibre of fruits and vegetables is important for the human diet. Fibre is usually classified chemically by its molecular size, with sugars (1-2 monomers) and oligosaccharides (3-9 monomers) being digestible, whereas polysaccharides (>10 monomers) and lignin are non-digestible (i.e. dietary fibre) [14].

A number of studies have shown that a high-fibre diet is associated with improved glucose control, reduced risks of diabetes mellitus, cardiovascular disease, colon cancer and increased intestinal motility. These beneficial effects of dietary fibre are likely to be mediated via modulation of the colonic microflora and production of SCFAs such as butyrate, which are known to reduce chronic inflammatory pathways both in the colon and systemically.

It is recommended that adults should consume at least 5 portions of vegetables and 2 portions of fruit per day to ensure an adequate intake of nutrients such as vitamin C, potassium and dietary fibre. It is important to remember that different fruits and vegetables have different nutrient profiles, for example orange fruits are rich in carotenoids whilst dark green vegetables contain a large amount of dietary fibre.

Phytochemicals

Phytochemicals are plant-based bioactive compounds that have been shown to have health benefits. They can reduce the risk of cancer, prevent heart disease, regulate gene transcription and enhance gap junction communication. They also have antimicrobial, antioxidant, antidiarrheal and antispasmodic activities. More than a thousand phytochemicals have been identified and they can be found in whole foods, vegetables, fruits and herbs.

Eating a variety of fruit and vegetables is important because each offers different nutrients. For example, green leafy vegetables (e.g. spinach and broccoli) are high in vitamin C and potassium. Orange coloured fruits are high in carotenoids.

The phytochemical content of food varies greatly and the yield, purity and structural stability of extracted compounds depend on the method used. Enzyme-based extraction methods such as cellulase, a-amylase and pectinase offer better quality than hexane. However, these methods are expensive. They are also limited by the availability of enzymes. A more cost effective approach is the maceration method (soaking soft tissue in a solvent/menstruum for several days). This produces tinctures and extracts of the highest quality and is suitable for small batches.