Vegetables calcium from green leafy

Tables lO.l to 10.5 may be useful as an orientation and a source of specific information for sections in this chapter. Table 10.1 lists the inorganic nutrients in various foods. One of the more striking aspects of these data is the fact that potassium concentrations in plant foods are much higher than those of sodium. Another point, raised under calcium and phosphate, is that green leafy vegetables (broccoli) and dairy products (cottage cheese) are high in calcium, whereas meats have relatively low levels of this nutrient. The calcium/phosphate ratios of various fcKids are also discussed in this section. These ratios can be easily calculated from the data in the table. Food iron data from tw o sources are listed. Milk and milk products, which contain high levels of many nutrients, are very low in iron.

Calcium consists of six stable isotopes, " Ca, Ca, Ca, Ca, Ca, and Ca, with average natural abundances of96.941,0.647,0.135, 2.086,0.004, and 0.187%, respectively. All stable calcium isotopes can be used as tracers apart from Ca with its high natural abundance. The least abundant isotopes Ca, Ca, and Ca are most suitable, in particular for intravenous administration. The lower the natural abundance, the smaller is the required dose and, thus, its effect on calcium homeostasis in plasma. For isotopic labeling, differences in calcium speciation between the isotopic label and calcium in the meal or compound to be tested must be taken into account. Calcium absorption from intrinsically and extrinsically labeled meals was found to be equivalent for wheat [75] and dairy products [76], but not for green leafy vegetables [77, 78]. Heaney et al. [79] found a difference in calcium absorption from labeled calcium chloride and tricaldum phosphate when added to soy milk, but no difference for calcium carbonate and calcium citrate [80]. In the latter studies, the calcium salts were directly synthesized from the label as the standard procedure for intrinsic labeling of chemical compounds. 

Calcium deficiency may result from diets containing only small amounts of dairy products and/or green, leafy vegetables. 

SOURCES OF CALCIUM. Among common foods, the milk and milk products group contains many of the richest sources of calcium. Some leafy green vegetables and some fish are also rich sources of calcium. However, in the United States, more than 70% of the calcium intake is derived from milk and milk products. Other foods contribute smaller amounts. 

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