Chapter 4 Answers to self check questions

1 A diet high in trans-fats can raise blood cholesterol levels. If James reduces the amount of trans-fats in his diet, this should help to reduce his blood cholesterol levels. Trans-fats are found naturally in low levels in some foods. However, artificial trans-fats are found in many processed foods such as cakes and biscuits so reducing his intake of processed foods would help.

2 Trans-fats are formed by partial hydrogenation of the double bonds in unsaturated fatty acids. The normal configuration of the double bonds in unsaturated fatty acids is cis. Catalytic partial hydrogenation of unsaturated fatty acids converts some of the remaining double bonds to the trans configuration. Trans-fats raise levels of LDL (‘bad’) cholesterol and lower levels of HDL (‘good’) cholesterol.