Sir: Dietary supplements encompass a wide range of products that include vitamins and minerals, herbal products, amino acids, tissue extracts and other compounds. Many dietary supplements are extremely helpful in preventing illness; for example, folic acid can prevent birth defects, and calcium and vitamin D can prevent fractures. However, not all supplements are effective. Even worse, some might actually cause more harm than good. Little is known about the safety of supplements; all supplements are harmless until proven otherwise. Consumers should be careful when purchasing supplements. For an overall healthy lifestyle, regular exercise, eating a healthy diet, getting enough sleep, and visiting a healthcare professional regularly are also necessary.Tahira Suleman Karachi