Eat a diet high in
vitamin B12
and see if this improves your serum levels. The best sources of
vitamin B12 include eggs, milk, cheese, milk products, meat, fish, shellfish and poultry. Take probiotics to help increase good bacteria in the gut and make sure you have adequate stomach acid. If low, then supplement with betaine HCI with pepsin; supplements found at health food stores.
Try the baking soda (sodium bicarbonate, not baking powder) test...