Anxiety due to health worries.

Eat as much fat (meat, dairy) (and vegetables) as you want as it does not have much effect on blood cholesterol levels but cut down on processed food and carbohydrates (sugar, bread, pastry, pasta, cereal, fruit juice, potatoes) as they get converted in the liver to cholesterol. Eat plenty of nuts for snacks as they contain healthy fats and curb appetite.

Doing more exercise will help reduce cholesterol and anxiety levels.

Try to cut out coffee as that makes anxiety and heart rate worse.

It is worth talking to your doctor again about the heart murmur for further tests or reassurance. I found diazepam helpful as a short term medication for anxiety but doctors are often reluctant to prescribe, propranolol reduces the physical symptoms of anxiety of tight chest and racing heart but doesn't help the anxious thoughts. It might be also worth asking about counselling through your GP to help with the anxiety.

With diazepam it takes a few months of continuous use to get addicted. I take them just once or twice a week when very anxious (due to work related stress) and find them helpful, but get tired if I take them too often or when feeling more relaxed.

Although it is cholesterol that forms blockages in arteries, the traditional view that cholesterol in the diet (from meat, dairy, eggs etc.) causes this is not supported by current research, and a low fat diet (where often fat is replaced by sugar or other carbohydrates) can do more harm than good. There is also research that suggests that we consume too much vegetable oils which can cause inflamation in the body and this could be why deposits form in the arteries. I have switched back to butter and use coconut fat to cook with. If you look at the ingredients for many products they now contain palm oil, which is used because it is cheap, rather than healthy.

My levels of triglycerides (another fat carried in the blood) were 10 times what they should have been, due to an unhealthy diet and genetics (as other family members also had similar levels).

A lot of foods advertised and promoted as being healthy are full of sugar, good examples are breakfast cereals and yoghurts. Checking the information label for sugar should aim for 5g or less per 100g.

As you are not overweight be careful not to under-eat, but try to get a higher proportion of your calorie intake from protein and fat rather than carbohydrate. Obviously our circumstances and genetics are different and I am not medically trained, but I found I had a lot of misconceptions about food and reducing carbohydrates and exercise worked for me.