Q: With all the fortified products these days, do people need to take supplemental vitamin D?

A: It might be a good idea to supplement, particularly in the northern latitudes. Canadian researchers collected fasting blood samples every three months for one year from nearly 200 men and women. They found 34 percent of subjects had a vitamin D insufficiency in at least one of their blood samples. Researchers recommended additional vitamin D supplementation might be appropriate.1 This seems to be in concordance with a recent meta-analysis of studies on serum vitamin D levels in older people with hip fractures. This analysis revealed good evidence older people with hip fractures have reduced levels of vitamin D compared with controls.² The idea that vitamin D should be supplemented to prevent osteoporotic fractures, particularly in older women, is well supported.

Q: Is it true Co-Q10 may help with diabetes?

A: This interesting hypothesis has gained appeal in the past few years, yet its validity is still unclear.3 In four recent controlled trials, researchers looked at glycemic control and Co-Q10 supplementation. Results of the first suggested 120 mg of Co-Q10 per day improved various measures, from blood sugar levels to blood pressure.⁴ However, another trial published the same year suggested the opposite, showing no significant improvement, and two more trials published just last year failed to agree as well.5 The first study showed improved hemoglobin A1C (HA1C) levels after 12 weeks on 200 mg of Co-Q10 per day.6 HA1C is a long-term (two- to three-month) measure of blood sugar control. Results of this trial also showed a significant improvement in blood pressure, which has been documented with Co-Q10 in several studies. Yet in the second study using 200 mg per day, researchers did not show improved glycemic control.7 Why? It's hard to say. These were all placebo-controlled trials, yet the number of participants was small and differences in the types of patients in each trial may have created confounding variables. Unfortunately, this is the state of our knowledge. My advice is if a patient has diabetes and elevated blood pressure, then supplementing with Co-Q10, 150­200 mg per day, is reasonable. The literature is strong on blood pressure reduction and Co-Q10, however, since there are a variety of other dietary and nutritional therapies for diabetes, I might not use Co-Q10, at least initially, in a diabetic if he had normal blood pressure.

Q: Are there any nutritional treatments for hyperthyroidism?

A: It seems L-carnitine might have an effect. Carnitine is a vitamin-like nutrient related to the B vitamins. Essential for energy production and fat metabolism, it is synthesized in the liver, but infants, adolescents and adults under certain physiological conditions may produce insufficient amounts. Results of older studies in animals and unblinded human reports suggest the nutrient may also influence thyroid gland function.8 In a recent double-blind, placebo-controlled trial, 50 women were randomly assigned to three groups: placebo for six months; placebo for two months followed by 2 g or 4 g per day of L-carnitine for months three and four, then placebo for months five and six; or 2 g or 4 g per day of L-carnitine for the first four months followed by two months of placebo. Clinical symptoms such as palpitations and biochemical parameters worsened when patients took placebo, and returned to baseline or improved minimally during L-carnitine treatment. Bone mineral density also improved throughout the trial in all patients taking L-carnitine. The authors suggest the supplement may be useful for both preventing and treating hyperthyroidism.⁹

Dan Lukaczer, N.D., is director of clinical research at the Functional Medicine Research Center, a division of Metagenics Inc., in Gig Harbor, Wash.

References

1. Rucker D, et al. Vitamin D insufficiency in a population of healthy western Canadians. Can Med Assoc J 2002;166(12):1517-24.

2. Weatherall M. A meta-analysis of 25 hydroxyvitamin D in older people with fracture of the proximal femur. N Z Med J 2000;113(1108):137-40.

3. McCarty MF. Toward practical prevention of type 2 diabetes. Med Hypotheses 2000;54(5):786-93.

4. Singh RB, et al. Effect of hydrosoluble coenzyme Q10 on blood pressures and insulin resistance in hypertensive patients with coronary artery disease. J Hum Hypertens 1999;13(3):203-85.

5. Eriksson JG, et al. The effect of coenzyme Q10 administration on metabolic control in patients with type 2 diabetes mellitus. Biofactors 1999;9(2-4):315-8.

6. Hodgson JM, et al. Coenzyme Q(10) improves blood pressure and glycaemic control: a controlled trial in subjects with type 2 diabetes. Eur J Clin Nutr 2002;56(11):1137-42.

7. Watts GF, et al. Coenzyme Q(10) improves endothelial dysfunction of the brachial artery in Type II diabetes mellitus. Diabetologia 2002;45(3):420-6.

8. DeFelice SL, Gilgore SG. The antagonistic effect of carnitine in hyperthyroidism. Preliminary report. J New Drugs 1966;6(6):351-3.

9. Benvenga SR, et al. Usefulness of L-carnitine, a naturally occurring peripheral antagonist of thyroid hormone action, in iatrogenic hyperthyroidism: a randomized, double-blind, placebo-controlled clinical trial. J Clin Endocrinol Metab 2001;86(8):3579-94.

Natural Foods Merchandiser volume XXIV/number 3/p. 116