Salt and pepper mills, X-ray. Table salt (left) consists of crystals of sodium chloride. It is an essential part of the diet that is mainly obtained as part of a normal diet. Excess salt intake may lead to raised blood pressure. Peppercorns (right) are the dried fruit of the Piper nigrum plant. The metal parts of the mills (white) are revealed in this X-ray. Both pepper and salt are added to food as flavourings.