The phrase "high risk" means that there is a greater chance of something going wrong or not going as expected. It suggests that there are more potential dangers or negative outcomes involved. Full definition
This is why early diagnosis is important, so if you have been identified as at high risk of developing the disease you should be tested yearly. (womenshealthandfitness.com.au)
You really don't want to supplement since adding more cholesterol is generally associated with higher risk of heart attacks. (nutritionfacts.org)