Q: Can selenium supplementation help thyroiditis?
A: Thyroiditis is inflammation of the thyroid gland. The most common type is autoimmune thyroiditis, in which, for unknown reasons, the body attacks the thyroid gland, decreasing its production of thyroid hormones.
Selenium appears to have two essential functions in humans, both of which may be related to the thyroid. First, it is a component of the detoxifying enzyme glutathione peroxidase. If selenium is unavailable, this enzyme does not work as effectively. Since glutathione peroxidase helps to quench free radicals, lowered activity may result in increased free-radical generation and increased damage to an already inflamed thyroid gland.
Second, selenium is a key cofactor in the enzymatic conversion of thyroid hormone thyroxine (T4) to the more active triiodothyronine (T3). Poor conversion may also decrease thyroid function. Because of these connections, researchers have hypothesized that selenium supplementation may help in cases of autoimmune thyroiditis.
In two recent studies, researchers tested this idea by giving subjects T4 with or without selenium supplements. In both studies the combined supplementation of T4 and selenium, compared with T4 only, was beneficial in decreasing the autoimmune-induced inflammation as measured by antibodies against thyroid peroxidase, particularly in those with very high antibody levels.1,2 T3 levels were unchanged, which suggests selenium works, not by increasing levels of that hormone, but possibly by enhancing the activity of detoxifying enzymes, thereby protecting the thyroid gland against oxidative stress. Whatever the mechanism, these two studies do show selenium is helpful and well-tolerated at the dose of 200 mcg daily.
Q: Is soy useful as a source of iron?
A: Soybeans are rich in iron; one-half cup of soy nuts contains about the same amount as a 3-ounce serving of beef. However, the iron in soy may not be well-absorbed. Iron exists in two forms—heme and nonheme. Heme iron is part of the hemoglobin and myoglobin molecules in animal tissues. About 40 percent of the iron in meat is in the heme form. Although the body absorbs both forms, it absorbs heme iron much more efficiently than nonheme iron. (Vitamin C enhances the absorption of nonheme iron.) The iron in soy, as well as in other nonmeat sources, is nonheme. Complicating the iron-absorption issue are soy?s phytates, which can bind minerals such as iron and decrease absorption.3 Mineral absorption may be more efficient from fermented soy foods because of their reduced phytate content. So growing children and menstruating women should not rely heavily on soy as a primary iron source. Other good nonmeat food sources for iron include pumpkin seeds, molasses, leafy green vegetables (collards, kale, broccoli and other dark greens), eggs, legumes (lentils, red beans), apricots and figs.
Q: What dietary supplements would help a customer who recently had surgery to remove a piece of torn cartilage from a knee?
A: Partial meniscectomy is removal of part of a torn meniscus, the cartilage between the tibia and the femur in the knee joint. The menisci—there are two, a medial and lateral—play important roles in the knee?s biomechanics. Many years ago, a damaged meniscus was completely removed, but doctors discovered these operations increased the likelihood of osteoarthritis. Now only partial meniscectomies are performed as a general rule. Rarely, menisci can be repaired and not removed. Although the surgery is common and quite successful in returning a person to full activity, partial meniscectomy does eliminate some of the cartilage in that area. Therefore, there are questions as to whether this surgery does increase osteoarthritis risk. Two recent studies suggest it does, even for younger patients who have a torn meniscus from a traumatic injury.4,5
It makes sense, then, to encourage cartilage growth after such a surgery. For this task, I recommend glucosamine sulfate. It stimulates the synthesis of glycosaminoglycan, proteoglycan and hyaluronic acid, thus essentially increasing cartilage tissue. Results of long-term placebo-controlled trials show beneficial effects from oral glucosamine therapy in preventing joint-space narrowing and improving osteoarthritis symptoms.6,7 For someone with menisci knee surgery, taking glucosamine at least initially may help build cartilage. Although no studies have been done using glucosamine with patients who have had partial meniscectomy—such a trial would have to proceed for 10 to 15 years to assess results—supplementation makes sense. Because glucosamine has proven to be very safe, I think using it for three to six months after surgery is a reasonable therapy to pursue.
Dan Lukaczer, N.D., is director of clinical research at the Functional Medicine Research Center, a division of Metagenics Inc., in Gig Harbor, Wash.
1. Gartner R, et al. Selenium supplementation in patients with autoimmune thyroiditis decreases thyroid peroxidase antibodies concentrations. J Clin Endocrinol Metab 2002 Apr;87(4):1687-91.
2. Duntas LH, et al. Effects of a six-month treatment with selenomethionine in patients with autoimmune thyroiditis. Eur J Endocrinol 2003 Apr;148(4):389-93.
3. Hurrell RF, et al. Soy protein, phytate, and iron absorption in humans. Am J Clin Nutr 1992 Sep;56(3):573-8.
4. Englund M, et al. Impact of type of meniscal tear on radiographic and symptomatic knee osteoarthritis: a 16-year follow-up of meniscectomy with matched controls. Arthritis Rheum 2003 Aug;48(8):2178-87.
5. Englund M, et al. Patient-relevant outcomes 14 years after meniscectomy: influence of type of meniscal tear and size of resection. Rheumatology (Oxford) 2001 Jun;40(6):631-9.
6. Pavelka K, et al. Glucosamine sulfate use and delay of progression of knee osteoarthritis: a three-year, randomized, placebo-controlled, double-blind study. Arch Intern Med 2002 Oct 14;162(18):2113-23.
7. Bruyere O, et al. Correlation between radiographic severity of knee osteoarthritis and future disease progression. Results from a three-year prospective, placebo-controlled study evaluating the effect of glucosamine sulfate. Osteoarthritis Cartilage 2003 Jan;11(1):1-5.
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