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Salt consumption has been intensely studied for its role in human physiology and impact on human health. In particular, excessive dietary salt consumption over an extended period of time has been associated with hypertension and cardiovascular disease, in addition to other adverse health effects. Most forms of edible salt are composed primarily of sodium and chloride, as other minerals such as magnesium and calcium make unrefined salts bitter and therefore are rarely eaten.〔Ann Louise Gittleman, Sodium is essential to life. Total health magazine, vol 22, no 2.〕 An excessive intake of the ionic compound sodium chloride has long been suspected to increase blood pressure.〔 Sodium and chloride serum levels are both carefully controlled by the kidneys, and acute and chronic excessive intake of both ions can cause adverse health effect. However, only serum sodium is thought to be strongly correlated to blood pressure levels and cardiovascular disease. == Effect of salt on blood pressure == The human body has evolved to balance salt intake with need through means such as the renin-angiotensin system. In humans, salt has important biological functions. Relevant to risk of cardiovascular disease, salt is highly involved with the maintenance of body fluid volume, including osmotic balance in the blood, extracellular and intracellular fluids, and resting membrane potential 〔 The well known effect of sodium on blood pressure can be explained by comparing blood to a solution with its salinity changed by ingested salt. Artery walls are analogous to a selectively permeable membrane, and they allow solutes, including sodium and chloride, to pass through (or not), depending on the body's needs. Circulating water and solutes in the body maintain blood pressure in the blood, as well as other functions such as regulation of body temperature. When salt is ingested, it is dissolved in the blood as two separate ions - Na+ and Cl−. The water potential in blood will decrease due to the increase solutes, and blood osmotic pressure will increase. While the kidney reacts to excrete excess sodium and chloride in the body, water retention causes blood pressure to increase. Blood pressure may continue to increase as water is consumed hours after salt is ingested. As excess sodium is excreted by the kidneys, blood pressure drops accordingly. Diets that consistently contain high salt content will increase blood pressure over time . Fortunately, as many studies have shown, limiting salt intake in the diet can reverse these effects. Since most cases of hypertension are essential hypertension, it is unlikely that a single factor can be attributed to the cause of hypertension in most hypertensive patients. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Salt and cardiovascular disease」の詳細全文を読む スポンサード リンク
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