If you boil rice on v high heat & some bits are burnt black will this destroy the nutrients or have any other side effects? if you do quite regularly

No: It is not likely to have any ill-effects. Overcooking does damage some nutrients and you may wish to invest in a rice cooker. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex.