In her book Living Well With Hypothyroidism: What Your Doctor Doesn't Tell You. . . That You Need to Know, Mary Shomon quotes endocrinologist Kenneth Blanchard, M.D., of Lower Newton Falls, Massachusetts as saying, “The key thing is . . . doctors are always told that TSH is the test that gives us a yes or no answer. And, in fact, I think that's fundamentally wrong. The pituitary TSH is controlled not just by how much T4 and T3 is in circulation, but T4 is getting converted to T3 at the pituitary level. Excess T3 generated at the pituitary level can falsely suppress TSH.” Hence, many people who are simply tested for TSH levels and are found to be within “normal” range are, in fact, suffering from thyroid problems that are going undetected.

Ridha Arem, MD, Associate Professor of Medicine in the Division of Endocrinology and Metabolism at Baylor College of Medicine, agrees. He says that hypothyroidism may exist despite "normal range" TSH levels. In his book The Thyroid Solution he says:

Many people may be suffering from minute imbalances that have not yet resulted in abnormal blood tests. If we included people with low-grade hypothyroidism whose blood tests are normal, the frequency of hypothyroidism would no doubt exceed 10 percent of the population. What is of special concern, though, is that many people whose test results are dismissed as normal could continue to have symptoms of an under active thyroid. Their moods, emotions, and overall well-being are affected by this imbalance, yet they are not receiving the care they need to get to the root of their problems. Even if the TSH level is in the lower segment of normal range, a person may still be suffering from low-grade hypothyroidism.

Thus, if we were to include those who may be suffering from “low-grade hypothyroidism” the number could well be double the 13 million estimate.

Thyroid Cancer
The statistics on thyroid cancer in the U.S. also tell a disturbing tale. Since 1990, cancer statistics (see http://seer.cancer.gov/) show that the overall thyroid cancer incidence across all ages and races in the United States has been subject to a statistically significant annual increase of 1.4 percent, per annum. That increase was highest amongst females (1.6 % per annum). Also worth noting is the fact that between 1975 and 1996 the incidence of thyroid cancer has risen 42.1% in the United States. This increase was particularly notable in women and most recent figures as of 1996 show that the incidence of thyroid cancer has climbed to 8.0 per 100,000. The National Cancer Institute (NCI) notes that "the preponderance of thyroid cancer in females suggest that hormonal factors may mediate disease occurrence.”

Especially alarming is the rate of thyroid cancer among children. The NCI publication Cancer Incidence and Survival among Children and Adolescents: United States SEER Program 1975-1995 has reported that the most prevalent carcinomas in American children and adolescents younger than 20 years was thyroid carcinoma at 35.5 percent—more prevalent than the highly publicized melanomas (30.9 percent). Approximately 75 percent of the thyroid carcinomas occurred in adolescents 15 to 19 years of age.

What is Causing This Epidemic?
While more research needs to be done, it is generally accepted that diet plays a major role in thyroid health. For decades we have known that low iodine intake leads to low thyroid function and eventually to goiter. Iodized salt was intended to solve this problem, but it has not been the answer. There are a number of foods known as goitrogens that block iodine. Two goitrogens are quite prevalent in the American diet—peanuts and peanut butter and soybeans used most often in prepared foods as textured vegetable protein (a refined soy food) and soybean oil.

The rise of industrialization, corporate farming, and mass production of food has drastically changed our food supply from what our ancestors ate. Many studies show the detrimental effects of refined sugars and grains on our health. These foods are very taxing on the thyroid gland, and we consume them in large quantities.

Environmental stress such as chemical pollutants, pesticides, mercury, and fluoride are also tough on the thyroid. A growing body of evidence suggests that fluoride, which is prevalent in toothpaste and water treatment, may inhibit the functioning of the thyroid gland. Additionally, mercury may diminish thyroid function because it displaces the trace mineral selenium, and selenium is involved in conversion of thyroid hormones T4 to T3.

Truth About Fats and Oils
Many oils can negatively affect thyroid health. We cook with them almost every day and they are plentiful in commercially prepared foods. Expeller-pressed or solvent-extracted oils only became a major part of the American diet in the last century. It is possible they are among the worst offenders when it comes to the thyroid. They are known as vegetable oils or polyunsaturated oils. The most common source of these oils used in commercially prepared foods is the soy bean.

Large-scale cultivation of soybeans in the United States began after World War II and quickly increased to 140 billion pounds per year. Most of the crops are produced for animal feed and soy oil for hydrogenated fats such as margarine and shortening. Today, it is nearly impossible to eat at restaurants or buy packaged foods that don’t have soy oil in the ingredients. Often labels simply state “vegetable oil.”

Ray Peat Ph.D., a physiologist who has worked with progesterone and related hormones since 1968, says that the sudden surge of polyunsaturated oils into the food chain post World War II has caused many changes in hormones. He writes:

Their [polyunsaturated oils] best understood effect is their interference with the function of the thyroid gland. Unsaturated oils block thyroid hormone secretion, its movement in the circulatory system, and the response of tissues to the hormone. When the thyroid hormone is deficient, the body is generally exposed to increased levels of estrogen. The thyroid hormone is essential for making the ‘protective hormones’ progesterone and pregnenolone, so these hormones are lowered when anything interferes with the function of the thyroid. The thyroid hormone is required for using and eliminating cholesterol, so cholesterol is likely to be raised by anything which blocks the thyroid function.

(See http://www.efn.org/~raypeat/efatox.rtf: “Unsaturated Vegetable Oils: Toxic”)

There is a growing body of research concerning soy’s detrimental affect on the thyroid gland. Much of this research centers on the phytoestrogens ("phyto" means plant) that are found in soy. In the 1960s when soy was introduced into infant formulas, it was shown that soy was goitrogenic and caused goiters in babies. When iodine was supplemented, the incidence of goiter reduced dramatically. However, a retrospective epidemiological study by Fort, et al. showed that teenaged children with a diagnosis of autoimmune thyroid disease were significantly more likely to have received soy formula as infants (18 out of 59 children; 31 percent) when compared to healthy siblings (nine out of 76, 12 percent) or control group children (seven out of 54; 13 percent). (P. Fort, N. Moses, M. Fasano, T. Goldberg and F. Lifshitz J. Am. Coll. Nutr. 9 (1990), p. 164)

When healthy individuals without any previous thyroid disease were fed 30 grams of pickled soybeans per day for one month, Ishizuki, et al. reported goiter and elevated individual thyroid stimulating hormone (TSH) levels (although still within the normal range) in thirty-seven healthy iodine-sufficient adults. One month after stopping soybean consumption, individual TSH values decreased to the original levels and goiters were reduced in size. (Daniel R. Doerge, Hebron C. Chang, “Inactivation of thyroid peroxidase by soy isoflavones in vitro and in vivo” Journal of Chromatography B Vol. 777 (1, 2); 25; September 2002: 269-79)

For more information about the effects of soy in the modern diet, see the Weston A. Price foundation website: http://www.westonaprice.org/soy/index.html

Coconut Oil: A-Healthy Choice
Traditionally, polyunsaturated oils such as soybean oil have been used for livestock feed because they cause the animals to gain weight. These oils are made up of what is known as long chain fatty acids—the kind of fatty acids that promote weight gain. (See EFFECT OF DIETARY FAT SOURCE, LEVEL, AND FEEDING INTERVAL ON PORK FATTY ACID COMPOSITION by M.T. See and J. Odle)