Agriculture Reference
In-Depth Information
12.2
Importance of Vegetables in Human Dietary System
Vegetables are considered a cheap source of energy as compared to other foods
(Alertor et al.
2002
; Hussain et al.
2009
) but serve as a rich source of essential
nutrients such as carbohydrates, carotene, protein, vitamins, calcium, iron, ascorbic
acid, dietary fiber, and concentration of trace minerals (Salunkhe and Kadam
1995
).
Major nutritional components of some of the widely consumed vegetables are listed
in Table
12.1
. Indeed, vegetables are one of the important food components of
human diets world over and have numerous health benefits. Cruciferous vegetables,
for instance, contain protein, carbohydrate, and vitamins (ascorbic acid, folic acid,
tocopherols, and provitamin A). The cruciferous vegetables contain both major
essential mineral elements such as Ca, K, P, and Na, Mg, etc. (Singh et al.
2001
),
while Fe, Se, Cu, Mn, and Zn are micronutrients found in these vegetables. Among
the root vegetables, carrot is rich in carotenoids and dietary fibers with high levels
of several other functional components that aid in improving human health. Spin-
ach, on the other hand, has a high nutritional value and is extremely rich in
antioxidants and has vitamin A, vitamin C, vitamin E, vitamin K, Mg, Mn, folate,
betaine, Fe, vitamin B
2
, Ca, K, vitamin B
6
, Cu, protein, P, Zn, niacin, Se, omega-3
fatty acids, and folic acid. Spinach also has a high Ca content. Potato contains
several vitamins and minerals along with carbohydrate (starch) (
26 g/medium-
sized potato). The starch of potato has the similar physiological effects and health
benefits as fiber and offers protection against colon cancer, improves glucose
tolerance and insulin sensitivity, lowers plasma cholesterol and triglyceride con-
centrations, and reduces even fat storage. Tomatoes on the contrary are versatile
vegetable in daily dietary practice and contain lycopene, one of the most powerful
natural antioxidants. Lycopene has also been shown to protect against oxidative
damage in many epidemiological and experimental studies. In addition to its
antioxidant activity, other metabolic effects of lycopene have also been demon-
strated. Tomato consumption has been associated with decreased risk of breast,
head, and neck cancers and might be strongly protective against neurodegenerative
diseases. In general, diets rich in these foods are associated with a lower risk of the
chronic disease of cancer (Hennekens
1986
) and heart diseases (Vanpoppel
et al.
1994
). Apart from human health benefits, vegetables in general improve the
quality of the soil where they are growing (Hussain et al.
2010
).
12.3
Importance of P to Some Vegetable Crops
Worldwide crop production remains limited due to low phytoavailability of P (Abd
El-Salam et al.
2005
; Khan et al.
2010
). Therefore, it is required at regular basis to
overcome the P deficiency to crop plants in P-deficient soils. Among different
vegetables, potato, for example, has a relatively high P requirement, but it uses
soil P inefficiently due to the limited accessibility of P. However, from the primary
