Then there was the reader last time who has vertical ridges on her fingernails and horizontal ones on her toenails. What do these signify? They can be caused by a vitamin B deficiency, severe stress or it could indicate a tendency for arthritis, says one reader. Transverse, or horizontal, ridges often indicate stress, and they can occur when a woman menstruates. Vertical ridges indicate an iorn deficiency, another reader tells us. Dowsing, vega testing, radionics or kinesiology may also help ascertain the cause. Another readers wonders if a fungal disease is causing the ridges. If so, rubbing castor oil onto the nails should do the trick. Then again, poor nutrient absorption could be the cause, which may suggest a leaky gut or candida. Take psyllim husk and vitamin C powder and probiotics to help clear the problem.