Nitrates are salts of nitric acid. The primary toxicity of nitrates is relatively low. Nitrates and nitrites are permitted as food additives in Europe under E 249 - E 252. They are mainly added to meat, as their addition preserves the fresh, red colour of the meat.
Organic nitrates can release nitric oxide (NO) in the body. This leads to a rapid dilatation of the vascular musculature. The blood vessels as well as the coronary arteries dilate immediately. This effect is used medically in the case of an attack of angina pectoris. At the same time the blood pressure is lowered.