# Seareed Exhibits Therapeutic Properties against Chronic Diseases: An Overview
## 4 Nutritional Value of Seaweed
### Minerals and Vitamins  
Seaweeds are rich sources of important minerals and vitamins. However, amounts vary according to seaweed species, phylum, season, and environmental, geographical, and physiological factors. In particular, seaweeds contain substantial amounts of calcium (Ca), magnesium (Mg), sodium (Na), phosphorus (P), iodine (I), zinc (Zn), and iron (Fe), at much higher levels than in terrestrial plants. Ca and Mg were found to be the major minerals in seaweed. A study of several seaweeds from the Kenyan Coast demonstrated that brown seaweed (_Hypnea musciformis_ and _Sargassum oligocystum_) and red seaweed (_Laurencia intermedia_) contain high amounts of Ca and Mg [67]. Calcium phosphate is more bioavailable in seaweeds than calcium carbonate, which is found in milk [57]. [PERSON] and colleagues [66] demonstrated that 8 g of _Ulwa lactuca_ (sea lettuce), which provides 260 mg of Ca, provides approximately 37% of the RNI of Ca for an adult male, while cheddar cheese only provides 5% of the RNI in the same portion. Furthermore, seaweed also contains one of the best natural sources of P, which is beneficial in the human diet. According to the World Health Organization (WHO) and Food and Agriculture Organization (FAO), the dietary reference value of P for adults (>13 years) is 700 ug/day [7]. Brown algae have been identified as important sources of I for the prevention and treatment of iodine deficiency goiters. The daily intake of I for adults is 150 ug/day, and excessive consumption should be avoided [7]. Ca and P are essential for heart and smooth muscle contraction, as well as for the skeleton. Mg is an important cofactor of many enzymes, including those involved in cellular respiration, while Na is responsible for maintaining the body's water and electrolyte balance. A high intake of Ca, Na, and K is linked to a lower mean systolic pressure and a lower risk of hypertension [7].  
Edible seaweeds are also a valuable source of vitamin content, particularly water-soluble vitamin C and B complexes and the fat-soluble vitamins A and E [21]. A study on several red seaweeds showed that, in general, the concentration of vitamin C was higher than that of vitamin A and vitamin E [61]. Research by [PERSON] and [PERSON] [57] reported that red and brown algae are rich in vitamin C and A. _Undaria pinnatifida_ and _Porphyra umbilicalis_ are rich in B vitamins [7]. Vitamins A, B, C, and E are important antioxidants produced by seaweeds. Vitamin A is found in large amounts in _Fucus spiralis_ (1.41 mg/100 g of dry weight), _Osmundea pinnatifida_ (1.20 mg/100 g of dry weight), and _Porphyra/Pyropia_ spp. (1.27 mg/100 g of dry weight). Vitamin C is present in large amounts in _Ulva lactuca_ (10 mg/8 g of dry weight) and _Undaria pinnatifida_ (14 mg/100 g of dry weight). Vitamin B12 is abundant in species such as _Ulva_ spp. and _Porphyra/Pyropia_ spp., with a recommended dietary allowance (RDA) of 2.5 mg/day for adults [66]. These findings indicate that seaweed minerals and vitamins have a greater potential to be exploited in high-demand functional food categories.