DH has high blood pressure and too many red blood cells - can this be fixed by lifestyle changes?

[Titsywoo]

So DH went to the GP a couple of weeks ago with low back pain that has been going on for a couple of months. His BP was 152/115 so he was told to keep a BP diary for a week or so and had lots of blood drawn for testing.

He went back today and was told he has polycythemia (excess red blood cells) and they need to do a kidney scan and chest xray. They did an ECG which they said was normal. His BP hasn't come down so they have given him Ramipril.

He has been very tired recently and feeling unhealthy in general. He works a lot (mostly at home at the moment but it's non stop from 9am until he goes to bed - emails, phonecalls etc). He also travels a lot for work. He loves his job but it can be stressful. He smokes about 20 a days, his BMI is about 29, he does no exercise and eats badly (no fruit or veg lots of carbs and sugar). He is 38. I'm pretty sure he has aspergers (our DS does and DH although very high functioning is very similar). This has caused food issues since childhood which never got sorted so he eats a very limited (and bad) diet.

He's concerned about the BP medication as a side effect is tiredness. He would need to make big changes but if he did could he bring his BP down naturally and not have to stay on medication. Obviously this is presuming there isn't another cause to these problems.

GP is just getting on with tests and not really dealing with the back pain or tiredness at the moment (understandably) so I'm just trying to work out what he can do to help himself. Any ideas or stories of similar experiences would be appreciated! Thanks :)