Fruits and vegetables are good for us – but why?

Fruits and vegetables are good for us – but why?

In the UK there are worrying reports that a lot of people, particularly young people, do not eat a mixed, balanced diet with a wide variety of foods and enough fruits and vegetables.  It is widely accepted that fruits and vegetables are good for us and many national governments run promotions aimed at encouraging increased consumption.  Granny used to say ‘Eat up your greens’, and there’s the saying ‘An apple a day, keeps the doctor away’.  Granny was right, but why?  Why should we eat our fruit and veg? 

The human body needs to get a number of different compounds from food, to keep us healthy, fit and active.  This is just a brief look at what fruits and vegetables have to offer.

Fruits and vegetables provide us with a range of compounds, many of which have more than one role, being involved both with immediate good health and with protection against diseases that develop over a long period of time, such as cancer, heart conditions, stroke and diabetes.

Vitamins are essential substances that the human body cannot make for itself so we have to get them from food.  Profound deficiency quickly leads to serious illness and lower-than-optimum intake will affect general well-being and quality of life. 
The fat-soluble vitamins A, E and K :
The fat-soluble vitamins A, E and K are stored by the body so although regular intake is needed this does not have to be everyday. 
Vitamin A is essential for growth and normal function of the retina of the eye.  Red, orange and yellow fruits and vegetables are a good source of pro-vitamin A, which is converted in the body. 
Vitamin E, found in vegetable oils, seed oils, cereals and avocado pears, is a potent antioxidant, involved in the formation of body tissues. 
Vitamin K, found in fresh green vegetables and fruit, is necessary for normal blood clotting.

The water-soluble vitamins B and C :
The water-soluble vitamins B and C, are not stored in the body so must be eaten frequently to maintain good health. 
Vitamin B is made up of several compounds essential for a healthy metabolism.  Green leafy vegetables, mushrooms and fruit are good sources.  The complex comprises B1 (thiamine), B2 (riboflavin), B6 (pyridoxine), B12 (folate) and B3 (niacin).  These vitamins have been traditionally grouped together because of similarities in their properties and functions. 

Vitamin C is needed for healthy gums, teeth and bones and it helps to speed up wound healing.  Acute-deficiency leads to scurvy.  [bgcolor=#ffff00]Vitamin C, along with vitamin E, is a potent antioxidant; it has a role in enhancing the action of vitamin E and in aiding the absorption of iron.  Good sources of vitamin C are citrus fruits, berries, blackcurrants, sweet peppers and green, leafy vegetables.  Potatoes contain modest amounts of vitamin C but they are a useful source as we eat them regularly and in fairly large proportions[/bgcolor].

Minerals are needed in enzyme systems and for other body functions.  Potassium, which is mainly derived from fruits and vegetables, has an important role in health.  Deficiency leads to muscular weakness, mental confusion and heart problems.  The amounts of minerals contained in fruits and vegetables depend on variety, climate, cultivation and soil type.

The body needs iron to make haemoglobin.  Haemoglobin is the substance that makes your red blood cells red and is used to carry oxygen around the body.  Meat and fish are good sources of easily absorbed iron.  Some plant foods, such as beans and lentils, also contain a lot of iron but it is not in a form that is easily absorbed by the body.  To help improve iron absorption from plant foods it is recommended that you eat vitamin C rich fruits or drink a glass of fruit juice with the meal. 

Fruits and vegetables help to protect us from illnesses that take time to develop.  What we eat now will affect our health in twenty years time – the time taken for some illnesses such as heart disease and cancer to develop.  Fruits and vegetables are sources of a range of antioxidants, the so-called ACE vitamins, (vitamins A, C and E), which help to prevent DNA damage.  Lycopene, found in tomatoes and the compound, lutein, found in broccoli, spinach and red peppers are also potent antioxidants.

Other protective compounds from fruit and vegetables include carotenoids, flavonoids, isothiocyanates and other substances that are often grouped together as ‘phytochemicals’.  Phytochemicals simply means, plant chemicals.  They contribute to the vivid, bright colours found in fruits and veg, which have a profound effect on our health.  Researchers are currently studying hundreds of these phytochemicals. 

Sinigrin, from Brussels sprouts, helps to protect us from cancer.  It works by persuading pre-cancerous cells to commit suicide by a natural process called apoptosis.  Sulphoraphane, from broccoli, also has powerful anti-cancer effects but, unlike sinigrin, it works by blocking cancer rather than suppressing it.  Other vegetables such as cabbage, cauliflower and kale also have useful amounts of these protective phytochemicals.

The carotenoids, -carotene, -carotene and -cryptoxanthin have pro-vitamin A activity and are converted into vitamin A in the body.  Carrots and pumpkins are excellent sources of -carotene and carrots, spinach, peaches and apricots are rich sources of -carotene and -cryptoxanthin occurs in oranges and some other fruits.

The beneficial components of fruits and vegetables reinforce one another and we get best overall effect by eating a wide range of produce. 

What we eat does affect our health.  We need to eat some foods from each of the four main groups every day.  These groups are:
•   starchy foods, which include bread, pasta, rice, breakfast cereals and potatoes
•   dairy products that include milk, cheese and yoghurt
•   meat and fish
•   fruits and vegetables

Fresh, frozen and canned fruits and vegetables are all useful.

Enjoy your food and remember eating is supposed to be fun and having fun is all part of a healthy lifestyle.

Written by:
Jenny Matthew and Dawn Barrett
Institute of Food Research

Issued by:
Communications Office
Institute of Food Research
Norwich Research Park
Colney
Norwich NR4 7UA


Tel: +44 (0) 1603 255 328
Fax: +44 (0) 1603 255 168
www.ifr.bbsrc.ac.uk


Further information can be found on the following web sites:

www.horticom.com/tem_aut/congres.html (both English and Spanish texts available)
www.ifr.bbsrc.ac.uk/fhbc/newsletter1.pdf part I
www.ifr.bbsrc.ac.uk/fhbc/newsletter2.pdf part II
www.fruitveg.com/uk/welcome.html