Is it true that b12 levels in the low-normal range could cause neurological problems, such as peripheral neuropathy?

May be: Low normal in older folks are more of a concern. Your doctor could get a urine test to see if your "low" levels are causing any metabolic issues. It would not do any harm to take oral vitamin B12. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Drink enough water daily so that your urine is mostly colorless. Practice safe sex.