Yes, it is true that it is no longer necessary to do a blood test to measure cholesterol after the age of 75. This is because there is limited data on the benefits of measuring cholesterol levels in older individuals, and the existing mathematical models used for treatment recommendations may not be accurate for this age group. Despite the known risks of high cholesterol, it is recommended for individuals over 75 to focus on healthy lifestyle habits such as staying active, avoiding smoking, eating fruits and vegetables, avoiding saturated fats, and following a Mediterranean diet if possible. However, the impact of these measures may not be tested through blood tests.