Which word in the passage means 'easy to damage or break'?

Vitamins and minerals are essential nutrients because they perform hundreds of roles in the body They help shore up bones, heal wounds and bolster our immune system. They also convert food into energy, and repair cellular damage. They are known mainly by their initials (such as vitamins A,B,C,D,E, and K—to name just a few). Vitamins and minerals are often called micronutrients because our body needs only tiny amounts of them. Yet failing to get even those small quantities virtually guarantees disease. Although they are all considered micronutrients, vitamins and minerals differ in basic ways. Vitamins are organic and can be broken down by heat, air or acid. Minerals are inorganic and hold on to their chemical structure. It means the minerals in soil and water easily find their way into our body through the plants, fish, animals and fluids we consume. But it’s tougher to shuttle vitamins from food and other sources into our body because cooking, storage and simple exposure to air can inactivate these more fragile compounds. There is a fine line between getting enough of these nutrients (which is healthy) and getting too much (which can end up harming you). Eating a healthy diet remains the best way to get sufficient amounts of the vitamins and minerals you need.