Post Ride Illness

I ride to work everyday in all weathers and Im frequently ill.  

I find that diet makes the best difference and eating loads of rubbish really doesnt help.  I also find that the Boots cold sinus spray stuff really does work and Wellman vitamins and cod liver oil appears to help with lethergy.

You could be overtraining, you should rest until you feel completely better. As you mention, exercising can lower your immune system so maybe you just aren't giving your body the chance to fully recover before you go for your next ride.  Ensure you are eating a balanced diet and resting plenty, then once you are feeling fully fit get back out there and just take it slowly.

the one supplement British rowing advocate is brazil nuts for the selenium (which boosts the immune system).

Whilst anecdote isn't evidence 3-4 brazil nuts a day has seen me right over the last several years.

That said,make sure you are only training when you are well, otherwise you are inviting other problems

Sounds like Overtraining....so to much / to hard with not adequate recovery . Take some time off or go easy. Yes your more susceptible when overtraining and your asthma certainly will have an affect, do you get hay fever ? Recovery wise it's more rest than anything else although after a hard / long session I've noticed I recover faster with a SIS Rego shake ...so I can ride hard / long again the next day 

I am a bit sceptical about there being specific immune boosting foods I have to say- like everything you need a good balanced diet with plenty of fresh fruit and veg.

Exercise should be good for you, you have to be really going some to do so much it knackers your immune system- are you taking time to recover and eating well?

I am a bit sceptical about there being specific immune boosting foods I have to say- like everything you need a good balanced diet with plenty of fresh fruit and veg.

Exercise should be good for you, you have to be really going some to do so much it knackers your immune system- are you taking time to recover and eating well?

Go to bbcgoodfoods.com and they list immune boosting foods.  Try doing a little less on your bike until you feel better.

Have you tried talking to your GP, and maybe getting some blood tests / allergy testing done?

In my case it was gluten intolerance but not with your symptoms. I experienced nausea and fatigue after cycling and had to stop for 15 years before finally diagnosing it myself.

I know of at least 3 people that have suffered from various viral & bacterial infections after riding in "agricultural" areas - where cow muck & the like has been kicked up on to their drink bottles from the road and then they've swigged without cleaning...

Personally I just get hayfever when riding between May & August - and only when riding - in normal wandering around there are no symptoms - I can only surmise that the extra effort means I get a lot more irritants so the symptoms are amplified. Antihistamine stops it outright though.