Q: My doctor says I need to take vitamin D-3, but I know from past history that vitamin D-3 upsets my stomach, no matter what the dose.
I was pleased to learn that there are two different kinds of vitamin D-3 (cholecalciferol). The most common is animal-based, but the other is plant-based. It is derived from lichen. This does not upset my stomach, and I'm grateful to have learned the difference.
A: Frequently when doctors discover that a patient has insufficient vitamin D circulating in the body, they will prescribe 50,000 IU per week of vitamin D-2 (ergocalciferol). This supplement is derived from plant sources, and it has been considered equivalent to vitamin D-3. A systematic review last year found that while supplementation with vitamin D-3 reduces mortality, vitamin D-2 has no impact on longevity (Cochrane Database of Systematic Reviews, Jan. 10, 2014). Perhaps prescribing practices should change in light of this evidence.
The form of vitamin D-3 that you encountered is relatively new. It is marketed under the name Vitashine and is included in several brands of vegetarian vitamin D-3 supplements. We are glad to hear that it does not cause you digestive distress.
We offer much more detail about the consequences of inadequate vitamin D along with recommendations on supplementation in our Guide to Vitamin D Deficiency. Anyone who would like a copy, can download it for $2 from our website: peoplespharmacy.com.
Q: You've discussed treatments for restless legs syndrome (RLS) in your column, but you have not mentioned folic acid.
Decades ago, I was renting a room from a medical student. She observed my dis
tress and pointed out a page in a textbook. That was the first time I had ever heard of "restless legs syndrome." The book said that it was caused by folic-acid deficiency.
I started taking folic acid, and it worked like gangbusters. It's cheap and readily available, and it has never stopped working for me.
A: Your report is fascinating. Restless-legs syndrome has been attributed to vitamin D deficiency (Neuropsychiatric Diseases and Treatment online, May 21, 2014) or lack of iron (Sleep Medicine, December 2014). Although folic-acid deficiency is considered less often, it, too, seems to be linked to RLS (Alternative Medicine Review, June 2007).
Q: I had never had a urinary-tract infection (UTI) until I was 65 years old. Then I had two within a few months of each other.
When I saw the urologist about this unwelcome development, she recommended I take a cranberry tablet each day as well as a spoonful of a powder called D-mannose. This has solved my problem. I have not had another UTI since then, for which I am very thankful.
A: There has not been much research on this combination for preventing urinary-tract infections, although other readers have reported success with one or the other of these supplements. A recent pilot study suggests that the combination of cranberry, D-mannose and two probiotics in the Lactobacillus family might alleviate the symptoms of acute cystitis (Journal of Clinical Gastroenterology, Supplement 1, November-December 2014).
In their column, Joe and Teresa Graedon answer letters from readers. Email them via PeoplesPharmacy.com. Their newest book is "Top Screwups Doctors Make and How to Avoid Them."