Probiotics is known to boost the immune system of the body although I am uncertain if it can help treat Lyme since Lyme is essentially parasite in the blood.
Late last year I was bitten by a deer tick in Mass, USA. Developed a rash around the bite area with a distinct "ring" - sure sign of deer tick's bite. Went to see doc within 7 days and all they could do to treat was Antibiotics . Took a course for 21 days and although I should have rechecked, did not since I did not experience any debilitating effects or illnesses. Will do so some time.
Another very good immune boosting natural food is mushrooms. The best are shiitake, maitake, wood ear, oyster, himmenmatustake, ling zhi, reishi, yun zhi, cauliflower or a combination of these in powder form. They help boost the macrophage and T-cells mostly against carcinogenic matter that invade the body.