Nutrition Q&A with Dan Lukaczer, N.D. 35461

Q: Will supplementing with the amino acid taurine improve blood sugar control in diabetics?

A: Several animal studies have shown taurine reduces blood sugar, abdominal fat accumulation and insulin resistance.1 I am aware of two human studies in which researchers assessed taurine supplementation in diabetics. Results of a small, older uncontrolled trial did suggest taurine may help with glucose control.2 The first controlled human trial did not show any effect of taurine on blood sugar, insulin or cholesterol levels after four months of supplementation.3 However, taurine may still play an important role in diabetes control because of its powerful antioxidant effect. In animal studies, taurine supplementation has been helpful for some complications associated with diabetes, such as diabetic retinopathy.4 This, in all likelihood, is not attributable to taurine?s ability to lower blood sugar, but to its antioxidant activity.5 Again, we are only looking at animal studies, but given its safety and the significant research on taurine as an antioxidant, taurine may help prevent the free radical damage associated with various diabetic complications.

Q: What dietary considerations and nutritional supplements should people with recurrent kidney stones be aware of?

A: More than 500,000 individuals suffer from kidney stones each year, necessitating 200,000 hospitalizations. During the course of his lifetime, a man has a 10 percent chance of developing stones. Nutrition and supplementation are important in preventing kidney stones. Most are of the calcium oxalate variety; therefore, the most important considerations have to do with controlling oxalate intake and increasing oxalate solubility in the urine so the oxalic acid salts don?t crystallize and form stones. Several foods contain oxalates: topping the list is spinach, but rhubarb, beets, nuts, chocolate, tea, wheat bran and strawberries also contain significant amounts. Limit consumption of these foods. As far as increasing solubility, this means staying well hydrated with plenty of water each day. Magnesium, potassium and B6 top the list of nutrients with potential to improve solubility.6^,7 And last, disregard the common recommendation to keep calcium intake low. The opposite is true. Increasing calcium in the diet has been shown to decrease the incidence of calcium oxalate stones in recurrent stone formers, in part by binding oxalates from food.8^,9^,10

Q: Will isoflavones help prevent bone loss and osteoporosis?

A: It is quite possible. Hormone replacement therapy for preventing osteoporosis is no longer readily accepted by most women, largely because of increased breast cancer risk. Isoflavones may be a natural alternative. Studies involving younger women show isoflavones appear to have little or no effect on bone,11 but women beginning menopause may gain some benefit. Results of a recent population study assessing dietary intake showed soy protein/isoflavones had a modest but significant association with hip bone mineral density.12 Initial controlled trials with humans also show isoflavones have a modest positive effect on maintaining bone mineral content in menopausal women with low initial bone mass.13 A recent study even compared the isoflavone genistein (54 mg/day) to standard HRT. In this small study, researchers found both genistein and HRT reduced bone resorption and increased bone formation in menopausal women compared with placebo.14 Women should have periodic bone mass evaluations (DEXA scans) because many factors affect bone loss. However, taking isoflavones for bone health looks promising.

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. Nakaya Y, et al. Taurine improves insulin sensitivity in the Otsuka Long-Evans Tokushima Fatty rat, a model of spontaneous type 2 diabetes. Am J Clin Nutr 2000;71(1):54-8.
2. Elizarova EP, Nedosugova LV. First experiments in taurine administration for diabetes mellitus. The effect on erythrocyte membranes. Adv Exp Med Biol 1996;403:583-8.
3. Chauncey KB, et al. The effect of taurine supplementation on patients with type 2 diabetes mellitus. Adv Exp Med Biol 2003;526:91-6.
4. Hansen SH. The role of taurine in diabetes and the development of diabetic complications. Diabetes Metab Res Rev 2001;17(5):330-46.
5. Di Leo MA, et al. Potential therapeutic effect of antioxidants in experimental diabetic retina: a comparison between chronic taurine and vitamin E plus selenium supplementations. Free Radic Res 2003;37(3):323-30.
6. Ettinger B, et al. Potassium-magnesium citrate is an effective prophylaxis against recurrent calcium oxalate nephrolithiasis. J Urol 1997;158(6):2069-73.
7. Bren A, et al. Magnesium hydrogen carbonate natural mineral water enriched with K(+)-citrate and vitamin B6 improves urinary abnormalities in patients with calcium oxalate nephrolithiasis. Urol Int 1998;60(2):105-7.
8. Curhan GC. Dietary calcium, dietary protein, and kidney stone formation. Miner Electrolyte Metab 1997;23(3-6):261-4.
9. Domrongkitchaiporn S, et al. Risk of calcium oxalate nephrolithiasis in postmenopausal women supplemented with calcium or combined calcium and estrogen. Maturitas 2002;41(2):149-56.
10. Massey LK, et al. Effect of dietary oxalate and calcium on urinary oxalate and risk of formation of calcium oxalate kidney stones. J Am Diet Assoc 1993;93(8):901-6.
11. Anderson JJ, et al. Soy isoflavones: no effects on bone mineral content and bone mineral density in healthy, menstruating young adult women after one year. J Am Coll Nutr 2002;21(5):388-93.
12. Ho SC, et al. Soy protein consumption and bone mass in early postmenopausal Chinese women. Osteoporos Int 2003;14(10):835-42.
13. Chen YM, et al. Soy isoflavones have a favorable effect on bone loss in Chinese postmenopausal women with lower bone mass: a double-blind, randomized, controlled trial. J Clin Endocrinol Metab 2003;88(10):4740-7.
14. Morabito N, et al. Effects of genistein and hormone-replacement therapy on bone loss in early postmenopausal women: a randomized double-blind placebo-controlled study. J Bone Miner Res 2002;17(10):1904-12.

Natural Foods Merchandiser volume XXV/number 1/p. 58