Dr. Cannell Answers Readers' Questions

Major Depression

No, it has not. Although I'm glad you are feeling better, there are no studies in the literature showing vitamin D effectively treats major depression, only that it improves mood or well-being, an important difference. However, there are some compelling reasons to think it might help major depression.

Dr. Reinhold Vieth found 4,000 units of cholecalciferol (vitamin D3) a day was better than 600 units in improving well-being in endocrinology outpatients. Two studies using 800 units a day to improve mood gave conflicting results, but neither of these studies had patients with major depression. Lastly, low levels of vitamin D were associated with high depression scores in a recent Tromso Study. Vieth R, Kimball S, Hu A, Walfish PGRandomized comparison of the effects of the vitamin D3 adequate intake versus 100 mcg (4000 IU) per day on biochemical responses and the wellbeing of patients.Nutr J. 2004 Jul 19;3:8. Dumville JC, Miles JN, Porthouse J, Cockayne S, Saxon L, King CCan vitamin D supplementation prevent winter-time blues? A randomised trial among older women.J Nutr Health Aging. 2006 Mar–Apr;10(2):151–3. Lansdowne AT, Provost SCVitamin D3 enhances mood in healthy subjects during winter.Psychopharmacology (Berl). 1998 Feb;135(4):319–23. Jorde R, Waterloo K, Saleh F, Haug E, Svartberg JNeuropsychological function in relation to serum parathyroid hormone and serum 25-hydroxy vitamin D levels: The Tromso study.J Neurol. 2006 Apr;253(4):464–70.

As a psychiatrist, I find vitamin 5,000 units of vitamin D a day cures some patients with major depression who have low vitamin D levels but has no effect on others. In the end, I predict vitamin D deficiency (levels less than 50 ng/mL) will be found to be one of many causes of major depression, though an important one.

Vitamin D Lamp

Until now, either you had to take frequent vacations down south, go to a sun tanning parlor, or buy an ultraviolet light. Recently a better option was introduced on the market by Sperti—a dedicated vitamin D lamp. The main advantage is it has few damaging UVA rays, has peak UVB outputs in the range that optimally triggers vitamin D production in the skin, makes large amounts very quickly, and can be used at home. I hope that sun tanning parlors will soon add this light to their salons so customers can have a wider choice of lights.

Pulmonary Function

No, that is not true. What you may be referring to is the most amazing study on vitamin D recently released. Using NHANES III data, Dr's. Black and Scragg discovered that vitamin D levels were strongly associated with pulmonary function (how well your lungs work). Who would have thought? They found that people with the highest vitamin D levels who had smoked had better pulmonary function than those with the lowest levels who had never smoked! That is, of two things that hurt your lungs (vitamin D deficiency and smoking) vitamin D deficiency may cause more damage than smoking! However, the study said nothing about lung cancer—so stop smoking. Black PN, Scragg RRelationship between serum 25-hydroxy vitamin d and pulmonary function in the third national health and nutrition examination survey.Chest. 2005 Dec;128(6):3792–8.

How Much, What Kind, Where to Get It

Great question! The only vitamin D you should take is cholecalciferol. No one knows for sure how much you should take but the easy answer is 2,000 units a day. The government says 2,000 units a day is safe to take on your own, without being under a doctor's care, and without getting blood tests. Two thousand units a day will do a lot of good. However, it may not be enough for some African Americans, the obese, the aged, and for people suffering from sunlight deprivation. The safest thing to do is to get a vitamin D level, or 25-hydroxyvitamin D, two or three times a year and take enough to maintain your level around 50 ng/mL (125 nM/L) year around. Remember your highest natural level will be in the early fall and your lowest level in the early spring.

If you take more than 2,000 units a day, you should have blood levels done periodically. To my knowledge, no one has ever given 5,000 units of cholecalciferol a day for three or four years to see what happens to blood levels. We think it will be okay but still are not completely sure. I take 5,000 units in the winter, 2,000 units in the early spring and late fall, and none in the late spring, summer, and early fall when I enjoy the sun. I maintain my levels around 50 ng/mL.

The best source of cholecalciferol (vitamin D3) I found is Bio Tech Pharmacal, Inc., a federally licensed and FDA approved manufacturer. They make a 1,000 (not yet listed on their website), 5,000, and 50,000 IU capsule. The 50,000 IU capsule can definitely cause vitamin D toxicity, is meant for health care providers, and should never be taken on your own. Most health food stores sell 1,000 unit capsules of plain cholecalciferol.

Mild Dementia

There is no interventional evidence; that is, no one has given that amount of vitamin D to mildly demented patients to see if it helps. Remember, once the brain shrinks, as it does in dementia, vitamin D should have little effect. Important animal research recently showed activated vitamin D3 acts as a powerful anti-inflammatory agent and completely reverses the age-related increase in the inflammatory markers that accompany dementia, meaning they discovered the mechanism by which vitamin D may prevent dementia. Moore ME, Piazza A, McCartney Y, Lynch MAEvidence that vitamin D3 reverses age-related inflammatory changes in the rat hippocampus.Biochem Soc Trans. 2005 Aug;33(Pt 4):573–7.

At least four studies have incidentally found that demented patients have low vitamin D levels. The obvious explanation is that demented patients dont go outside as much. However, Dr. Dhesi found associations between vitamin D and cognition within a narrow range of cognition, harder to explain by outdoor behavior. Dr. Flicker found the association, even after adjusting for outdoor exposure, suggesting causation. Kipen E, Helme RD, Wark JD, Flicker LBone density, vitamin D nutrition, and parathyroid hormone levels in women with dementia.J Am Geriatr Soc. 1995 Oct;43(10):1088–91. Dhesi JK, Bearne LM, Moniz C, Hurley MV, Jackson SH, Swift CG, Allain TJNeuromuscular and psychomotor function in elderly subjects who fall and the relationship with vitamin D status.J Bone Miner Res. 2002 May;17(5):891–7. Flicker L, Mead K, MacInnis RJ, Nowson C, Scherer S, Stein MS, Thomasx J, Hopper JL, Wark JDSerum vitamin D and falls in older women in residential care in Australia.J Am Geriatr Soc. 2003 Nov;51(11):1533–8. Sato Y, Honda Y, Hayashida N, Iwamoto J, Kanoko T, Satoh KVitamin K deficiency and osteopenia in elderly women with Alzheimer's disease.Arch Phys Med Rehabil. 2005 Mar;86(3):576–81.

Recently the Australians showed that multiple areas of the human brain contain both the vitamin D receptor and the ability to activate vitamin D into the powerful steroid hormone, calcitriol. This means vitamin D therapy may have implications for a wide variety of neurological and psychiatric illnesses. I'm glad your grandmother is better but I'm not surprised. One on the doctors I work with noticed similar improvements with his mildly demented mother. Eyles DW, Smith S, Kinobe R, Hewison M, McGrath JJDistribution of the vitamin D receptor and 1 alpha-hydroxylase in human brain.J Chem Neuroanat. 2005 Jan;29(1):21–30.

Athletic Performance

I've heard it from many of people; remember that activated vitamin D is a potent steroid hormone. I've never been a good athlete—and I'm still not—but my tennis game is clearly better since I've been maintaining my level at 50 ng/mL. The literature is actually quite convincing that vitamin D improves the athletic abilities of older people who are vitamin D deficient. That is, vitamin D makes them fall less, and improves their choice reaction time, muscle strength, percentage and area of type II (fast) muscle fibers, and balance. However, to date, no one has directly tested the theory by giving physiological amounts of vitamin D (5,000 units a day) to young vitamin D deficient athletes. I predict whomever does that study will be all over the news. Furthermore, idiopathic (which means the doctors are too idiotic to know why) low back pain is rampant among athletes, especially indoor athletes. There is good reason to think that many of them are vitamin D deficient. I'm not going to cite the references to any of this because I'm writing a paper. However, it looks as if levels of about 50 ng/mL will optimize athletic ability.

Vitamin D and the Flu

Dr. Hope-Simpson, one of my heroes, was an English general practitioner who became famous in 1965 after he single-handedly discovered the cause of shingles. It was one of the greatest discoveries by a GP in modern medical history. Hope-Simpson REThe Nature of Herpes Zoster: A Long-Term Study and a New Hypothesis.Proc R Soc Med. 1965 Jan;58:9–20.

After that he dedicated his life to studying influenza. I believe he correctly predicted that vitamin D plays a major role in preventing influenza epidemics although he didn't know it was vitamin D; he called it the "seasonal stimulus." Hope-Simpson REThe role of season in the epidemiology of influenza.J Hyg (Lond). 1981 Feb;86(1):35–47.

After reading Hope-Simpson and researching the topic, I wrote a newsletter about my theory. If you talk to people who keep their levels around 50 ng/mL, they will tell you they just don't get respiratory infections very often and if they do, they are mild. I believe the reason is simple: vitamin D dramatically increases the amount of naturally occurring antibiotics (antimicrobial proteins) in your lung and respiratory tract. Wang TT, Nestel FP, Bourdeau V, Nagai Y, Wang Q, Liao J, Tavera-Mendoza L, Lin R, Hanrahan JW, Mader S, White JHCutting edge: 1,25-dihydroxy vitamin D3 is a direct inducer of antimicrobial peptide gene expression.J Immunol. 2004 Sep 1;173(5):2909–12. Gombart AF, Borregaard N, Koeffler HPHuman cathelicidin antimicrobial peptide (CAMP) gene is a direct target of the vitamin D receptor and is strongly up-regulated in myeloid cells by 1,25-dihydroxyvitamin D3.FASEB J. 2005 Jul;19(9):1067–77. Liu PT, Stenger S, Li H, Wenzel L, Tan BH, Krutzik SR, Ochoa MT, Schauber J, Wu K, Meinken C, Kamen DL, Wagner M, Bals R, Steinmeyer A, Zugel U, Gallo RL, Eisenberg D, Hewison M, Hollis BW, Adams JS, Bloom BR, Modlin RLToll-like receptor triggering of a vitamin D-mediated human antimicrobial response.Science. 2006 Mar 24;311(5768):1770–3.

I have personally given 50,000 unit capsules of vitamin D to patients in early stages of what appears to be influenza (1,000 units/kg per day for three days—so a 120 pound person would take 50,000 units/day for three days and a 240 pound person would take 100,000 units/day for three days) and found it either stops their illness or ameliorates it. I find it has less effect on people with well-established respiratory infections and I don't understand why.

Cod Liver Oil and Vitamin A Toxicity

There are lots of studies showing cod liver oil helps lots of things. Did you know there are at least seven studies from the '20s and '30s showing it reduces colds, flu, and absenteeism in both children and adults? Did you know there are two recent studies indicating it either helps prevent or ameliorates respiratory infections in children? Which one of the three nutrients in cod liver oil: vitamin A, vitamin D, or omega-3 (fish oil) fats is responsible, or is it two of them, or is it the three combined? We don't know—at least I don't. I am leery of the vitamin A. Cod liver oil has anywhere from 5,000 to 15,000 units of preformed vitamin A in each tablespoon, sometimes more, besides the vitamin D and omega-3 fats. The question is what is the ideal amount and ideal combination of all three nutrients? The answer for vitamin D is becoming clearer: enough to get levels up to about 50 ng/mL year-round. Optimum omega-3 intakes are less clear and depend on the amount of omega-6 fats (most vegetable seed oils) in your diet. The answer for vitamin A is unclear, at least to me.

Vitamin A and vitamin D interact in unknown ways. Vitamin A protects against vitamin D toxicity and visa versa but we don't know why. There is increasing evidence that some Americans, perhaps quite a few, are suffering from sub-clinical vitamin A toxicity, mainly from the preformed vitamin A in their multivitamin supplements. Penniston KL, Tanumihardjo SAThe acute and chronic toxic effects of vitamin A.Am J Clin Nutr. 2006 Feb;83(2):191–201.

I am not convinced that because cod liver oil is "natural," it is therefore good. Tsunamis and strychnine are natural. In fact, cod liver oil is a processed food and Paleolithic man didn't drink it. There is evidence that at least one Paleolithic African women suffered severe vitamin A toxicity, probably from the liver she consumed. Chronic consumption of chicken liver caused vitamin A toxicity in twin girls. Walker A, Zimmerman MR, Leakey REA possible case of hypervitaminosis A in Homo erectus.Nature. 1982 Mar 18;296(5854):248–50. Mahoney CP, Margolis MT, Knauss TA, Labbe RFChronic vitamin A intoxication in infants fed chicken liver.Pediatrics. 1980 May;65(5):893–7.

A recent review of the literature found evidence that higher vitamin A levels are associated with bone problems. Women who consumed more than 15,000 units of vitamin A per day in food and supplements had a three and a half times higher risk for birth defects in their children than women who consumed less than 5,000 IU. Crandall CVitamin A intake and osteoporosis: a clinical review.J Womens Health (Larchmt). 2004 Oct;13(8):939–53. Rothman KJ, Moore LL, Singer MR, Nguyen US, Mannino S, Milunsky ATeratogenicity of high vitamin A intake.N Engl J Med. 1995 Nov 23;333(21):1369–73.

Vitamin A antagonizes the actions of vitamin D, probably at the receptor level, although that is not clear. The amount of vitamin A in one serving of liver antagonizes the rapid intestinal calcium response to physiological levels of vitamin D in man. Rohde CM, DeLuca HFAll-trans retinoic acid antagonizes the action of calciferol and its active metabolite, 1,25-dihydroxy cholecalciferol, in rats.J Nutr. 2005 Jul;135(7):1647–52. Johansson S, Melhus HVitamin A antagonizes calcium response to vitamin D in man.J Bone Miner Res. 2001 Oct;16(10):1899–905.

We just don't know if large amounts of vitamin A (more than 5,000 IU/day) causes problems when consumed with a large amount of vitamin D, as would be the case in people consuming large amounts of cod liver oil. A very well-written and entertaining rebuttal to my cod liver oil position, which I presented to the Weston A. Price Foundation, was recently published by that same foundation. However, Dr. Noel Solomon—a vitamin A researcher who spoke at the same conference—also cautioned against high vitamin A intakes. Masterjohn, CVitamin A on Trial; Does vitamin A Cause Osteoporosis?

In the end, my natural conservatism wins out. More is not better. What was the diet we evolved on? I know my Paleolithic ancestors didn't drink cod liver oil. Neither will I, unless my mother makes me, or until I have to choose between cod liver oil or nothing—and I don't.