NUTRITIONAL IMPORTANCE OF POTASSIUM, MAGNESIUM AND CALCIUM IN HUMAN NUTRITION
CHAPTER ONE
- Introduction
The significance of the mineral elements in hormones, animals and plants nutrition cannot be over emphasized. The pressure of mineral elements in animal feed is vital for the animal’s metabolic process. Grazing livestock from tropical countries often do not receive mineral supplementation except for common salt and must depend almost exclusively upon forage for their mineral requirements (McDowell et al., 1984). Mineral deficiencies or imbalance in soils and forages account partly for low animal production and reproduction problems. Soil acidity and season are factors affecting mineral uptake by plants.
There are two types of minerals important to the body – major minerals and trace minerals. Major minerals are the minerals of which the body requires the most quantities while trace minerals are minerals that are still essential to the body, but in smaller quantities.
The seven major minerals are Calcium, Phosphorus, Potassium, Sulphur, sodium, chloride and magnesium. The nine trace minerals are Iron, Zinc, Copper, Iodine, Selenium, Manganese, Fluorine, Chromium and Molybdenum.
Sweet potato, Ipomoea batatas L. (Lam) from the family convolvulaceae, is world’s sixth largest food crop which is widely grown in tropical, subtropical and warm temperate regions (Scott.,1992). The sweet potato plant is originated in central America but China is considered the leading producer of sweet potatoes, producing about 80% of the yearly global output (Li et al., 1992). About 40% of China’s annual sweet potato production is destined for animal, particularly pig feed use (Scott, 1992). The plant is widely cultivated and consumed throughout the world. It is an herbaceous perennial vine with alternate heart-shaped, lobed leaves and medium-sized flowers. The root is edible and is often long and tapered. The skin maybe red, purple or brown and white in colour. The flesh may be white, yellow, orange or purple. The leaves and shoots are eaten as vegetables (Zhao et al., 2005). In comparison to other major stable food crops, sweet potatoe has the following positive attributes, wide production geography, adaptability to marginal conditions, short production cycle, high nutritional value and sensory versatility in terms of flesh colours, taste and texture (Truong et al., 2010). It is commonly used as feed livestock and as a medicinal plant.
- Botanical Classification of Ipomoea batatas
Kingdom – Plantae
Phylom – Magnohiophyta
Class – Eudicotyledones
Order – Solanales
Family – Convolvulaceae
Genus – Ipomoea
Species – Ipomoea batatas
Local name – Ediam
- Constituents, Properties and Uses of Ipomoea batatas
Sweet potatoe roots are a good source of carbohydrates, an excellent source of vitamin A (in the form of beta-carotene), a very good source of vitamin C and manganese and a good source of copper, dietary fibre, vitamin B6, potassium and Iron (Candenas et al., 1993).
The roots and skin contain high levels of polyphenols such as anthrocyanins and phenolic acids (e.g. caffcic acid) (Konczak et al., 2003). Caffeoylquinci acid derivatives like chlorogenic, dicaffeoylquinic and tricaffeoylquinic acids are formed in the roots that protect them from fungal disease and have potential cancer chemoprotective effects (Konczak et al., 2003; Konczak et al., 2004).
The numerous acylated anthocyamins (Goda et al., 1997) are the major colour constituent in the storage root and are important in the plant’s use in diabetes (Matsui et al., 2004). Structural properties of the anthocyamins important for bioactivity include phenolic esters of the sugar, presence of 2 hydroscyl groups on the aromatic ring, and the presence of an unsaturated alkyl chain in the acylated moiety (Wilson and Burka, 1979).
- Pharmacological Properties
Owing to the large variety of constituents, sweet potato has been implicated in the treatment of more than ten pharmacological conditions. Research studies on sweet potatoes have focused on the following major areas; Antioxidant capacities, due to the presence of beta carotene, anthocyamins, caffeoyldancic acid and caffeoylquinic acid derivatives (Dini et al., 2006; Oki et al., 2006, Oki et al., 2002).
Antidiabetic properties due to flavones and proteins (Miyazaki et al., 2005; Zhao et al., 2007; Berberich et al., 2005).
Antiviral activities, due to caffeoylquinic acid derivatives (Kwon et al., 2000).
Anti-HIV, anti-diabetic, anti-inflammatory, hepatoprotective, gastroprotective, hypolipidemic and atherosclerotic effect due to triferpene saponins (Kashiwada et al., 1998; Banno et al., 2004; Saraswat et al., 1996, Lee et al., 2001, Min et al., 1999).
Anti-tumor effect at various stages of tumor development, including tumorigenesis inhibition, tumor promotion, induction of tumor cell differentiation, agiogeneisis and metastasis inhibitions (Lee et al., 2001, Somava et al., 2003, Liu, 2005; Lee et al., 1994; Cardenas et al., 2004).
- Antioxidant Properties
Sweet potatoes and preparations made from leaves of the sweet potatoe are powerful antioxidant (Ching et al., 2001). The plant’s antioxidant activity is associated with its alpha-tocopherol content, which is the most common form of vitamin E and comprises 25mg per 100g of sweet potatoe shoots (Ching and Maechima,
