Health importance of fruits and vegetables

Introduction

Botanically, a fruit is a part of a flowering plant that derives from specific tissues of the flower, one or more ovaries and in some cases accessory tissues. Fruits are the means by which these plants disseminate seeds. Many of them that bear edible fruits, in particular, are propagated with the movement of humans and animals in a symbiotic relationship as a means of seed dispersal and nutrition respectively. In fact humans and many animals have become dependent on fruits as a source of food (Lewis, 2002).

According to Schlegel (2003), fruits normally means the fleshy seed – associated structures of a plant that are sweet or sour and edible in the raw state, such as apples, oranges, grapes, strawberries, bananas and lemons.

In culinary terms, a vegetable is an edible plant or its part, intended for cooking or eating raw (Harri & Bianchini, 2003). They added that vegetables are most often consumed as salads or cooked in savoury or salty dishes, while culinary fruits are usually sweet and used for desserts but not the universal rule.

Gruda (2005) states that in everyday, grocery store, culinary language, the word fruits and vegetables are mutually exclusive; plant products that are called fruits are hardly ever classified as vegetables and vice versa.

Fruit structure and development

The outer, often edible layer of a fruit is the pericarp, formed from the ovary and surrounding the seeds, although in some species. Other tissues contribute to or form the edible portion. The pericarp may be described in three layers from outer to inner, the epicarp, mesocarp and endocarp (Mauseth, 2003).

According to Lewis (2002), fruit results from maturation of one or more flowers and the gynoecium of the flower(s) form all or part of the fruit. Inside the ovary/ovaries are one or more ovules where the mega gametophyte contains the egg cell. After double fertilization, these ovules will become seeds. The ovules are fertilized in a process that starts with pollination.

As the ovules develop into seeds, the ovary begins to ripen and the ovary wall, the pericarp, may become fleshy (as in berries or drupes) or form a hard outer covering (as in nuts). The pericarp is often differentiated into two or three distinct layers called the exocarp, mesocarp and endocarp (Schlegel, 2003).

According to Mauseth (2003), there are three general modes of fruit development which are;

1. Apocarpous fruits develop from a single flower having one or more separate carpels and they are the simplest fruits.
2. Syncarpous fruits develop from a single gynoecium having two or more carpels fused together.
3. Multiple fruits form from many different flowers.

Types of fruits

Plant scientists have grouped fruits into three main groups, simple fruits, aggregate fruits and composite or multiple fruits. The grouping is not evolutionally relevant, since many diverse plants types may be the same group, but reflect how the flower organs are arranged and how the fruits develop.

1. Simple fruits: Simple fruits can be either dry or fleshy and result from the ripening of a simple compound ovary in a flower with only one pistil. Dry fruits may either dehiscent (opening to discharge seeds) or indehiscent (not opening to discharge seeds). (McGee, 2004). Types of simple fruits are; achene (e.g. strawberry), caryopsis (e.g. wheat), drupe (e.g. coconut), legume (e.g. bean, peanut) berry (e.g. tomato), stone fruits (e.g. plum, cherry, peach), etc.
2. Aggregate fruits: Aggregate fruits form from single flowers that have multiple carpels which are not joined together, i.e. each pistil contains one carpel. Types of aggregate fruits include etaerois of achenes, follicles, drupelets and berries.
3. Multiple fruits: A multiple fruit is one formed from a cluster of flowers (called an inflorescence). Each flower produces a fruit, but these mature into a single mass. Examples are pineapple, fig, mulberry, osage-orange and bread fruit.

Parts of plants forming vegetables

Larkcom (2002) states that the list of food item called vegetable is quite long and include many different parts of plants amongst which are;

• Flower bud e.g. broccoli, capers, cauliflowers.
• Leaves e.g. spinach, beet green, turnip green, lettuce, etc.
• Leaf sheaths e.g. leaks
• Buds e.g. Brussels sprouts
• Stem e.g. ginger.
• Tubers e.g. potatoes, taro and yams
• Roots e.g. carrots
• Bulbs e.g. onions, shallots, garlic
• Fruits in botanical sense but used as vegetables e.g. tomatoes, cucumbers, pumpkins, egg plant, okra, avocado, etc.

Nutritional value of fruits and vegetables

Fruits are generally high in fibre, water, vitamin C and sugars, although this latter varies widely from traces as in limes, to 61% of the flesh weight of the date. Fruits also contain various phytochemicals which are required for proper long term cellular health and disease prevention (Kohli, 2008).

On the other hand, vegetables are eaten in a variety of ways, as part of main meals and as snacks. The nutritional content of vegetables varies considerably though generally they contain little protein or fat and varying proportions of vitamins such as vitamin A, vitamin K and vitamin B₆, provitamins, dietary minerals and carbohydrates (Harrison, 2009). Some vegetables also contain fibre, important for gastrointestinal function and contain important nutrients necessary for healthy hair and skin as well.

According to Munro and Small (2007), international dietary guidelines recommends 3 to 5 servings of vegetables daily. This recommendation can vary based on age and gender, and is determined based upon standard portion sizes typically consumed, as well as general nutritional content. For most vegetables, one serving is equal to ½ cup and can be eaten raw, cooked while a leafy green such as lettuce and spinach, a single serving is typically 1 cup.

Storage of fruits and vegetables

The plant hormone ethylene causes ripening of many types of fruits. Maintain most fruits in an efficient cold chain is optimal for post harvest storage with the aim of extending and ensuring shelf life. (Kohli, 2008). He added that this is also applicable for vegetables. During the storage, leafy vegetables lose moisture and the vitamin C in them degrades rapidly and they should be stored for as short a time as possible in a cool place, in a sealed container or in a plastic bag.

Health importance of fruits and vegetables

Eating fruits and vegetables are of great health importance as people who eat more fruits and vegetables as part of or an overall healthy diet are likely to have a reduce risk of some chronic diseases (Watson, 2010).

Gollner (2010) added that fruits and vegetables provide nutrients vital for health and maintenance of the body and summarized the health importance of fruits and vegetables as follows;

1. Eating a diet rich in fruits and vegetables may reduce the risk of heart disease including heart attack and stroke.
2. Diet rich in fruits and vegetables when consumed protects humans against certain types of cancers such as mouth, stomach, colon and rectum cancers.
3. Diets rich in foods containing fibre, such as fruits and vegetables may reduce the risk of obesity and type 2 diabetes.
4. Eating fruits and vegetables rich in potassium lowers blood pressure and may also reduce the risk of developing kidney stones and decrease bone loss.
5. Fruits and vegetables consumption provide the body with vitamin C which is important for growth and repair of all body tissues, helps heal cuts and wounds and keeps teeth and gum healthy.
6. Folic acid from fruits and vegetables help the body form red blood cells.

Hernandez (2010) opined that fruits and vegetables nutrition is a great way to strengthen the body’s immune system, fight disease and boast the overall body health as well as providing more water in one diet. Along with health benefits, eating fruits and vegetables can make weight management easier.

Conclusion/recommendation

In conclusion, it is of great importance finding out that fruits and vegetables provide health benefits and are important for the prevention of illness. Based on these, it is recommended that;

1. Individuals should try as much as possible to fill half of their plate with fruits and vegetables at each meal.
2. Individuals should eat the recommended amount of fruits and vegetables each day.
3. The government should organise seminars and workshops on the importance of fruits and vegetables to healthy living.
4. The general public should be encouraged to plants at least one type of fruit in their garden.
5. Medical practitioners and nutritionist should emphasize on the need for fruits and vegetables to their clients.

References

Gollner, A.J. (2010). The Fruit Hunters: A Story of Nature, Adventure, Commerce and Obsession. Scribner.

Gruda, N. (2005). Impact of Environmental Factor on Product Quality of Greenhouse Vegetables for Fresh Consumption. Critical Reviews in Plant Sciences. 24(3): 227-247.

Harri, V. & Bianchini, (2003). Fruits and Vegetables. Washington: IARC.

Harrison, J. (2009). The Essential Allotment Guide. United Kingdom: Right Way.

Hernandez, A. (2010). Why are Fruits and Vegetables Important? Washington: Western Michigan University Press.

Kohli, P. (2008). Fruits and Vegetables Post Harvest Care: The Basic. Crosstree Techno – Visors.

Larkcom, J. (2002). Grow your Own Vegetables. United Kingdom: Frances Lincoln.

Lewis, R. A. (2002). CRC Dictionary of Agricultural Sciences. London: CRC Press.

Mauseth, J.D. (2003). Botany: An introduction to Plant Biology. London: Jones and Bartlett.

McGee, G. (2004). Food and Cooking. New York: Columbia University Press.

Munro, D.B. & Small, E. (2007). Vegetables of Canada. NRC Research Press.

Schlegel, M. (2003). Encyclopaedic Dictionary. Munich Science Publishers.

Watson, R.R. (2010). Bioactive Foods in Promoting Health: Fruits and Vegetables. London: Academic Press.