How’s your thyroid doing? For most people who follow a CR Way lifestyle, the answer may be “turned down, thank you.” Calorie-restricted animals have decreased T3 output and for good reason: The whole point of CR is to slow metabolic rate and thus cell proliferation. For background on CR and thyroid see
Meredith and I aim for slightly low T3 and slightly high TSH.We have been strongly influenced by the work of Dr. Luigi Fontana and Dr. Martin Surks, a thyroid research specialist. Read more about Fontana and thyroid management in the new Thyroid and Aging page in Protection from Disease.
Here’s an important paragraph from the Fontana study:
“Effect of long-term calorie restriction with adequate protein and micronutrients on thyroid hormones.”
A paragraph from the full paper is very helpful: “Thyroid hormones influence cell respiration, free radical production and energy homeostasis. Although thyroxine (T4) is the main product secreted by the thyroid gland, most thyroid actions are mediated by triiodothyronine (T3). Data from studies conducted in long-lived rodents have shown that CR decreases serum T3 concentrations, while serum T4 and thyrotropin (TSH) concentrations usually remain unchanged”.
Another paper that looked at long lived Ashkenazi Jews was found that they have slightly elevated TSH.:
Atzmon G, Barzilai N, Hollowell JG, Surks MI, Gabriely I.
Department of MedicineDivision of Endocrinology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Journal of Clinical Endocrinology and Metabolism. 2009 Apr;94(4):1251-4.
CONTEXT: The distribution of serum TSH shifts progressively to higher concentrations with age.
OBJECTIVE: The aim of the study was to determine whether the population shift in TSH distribution to higher concentrations with aging extends to people of exceptional longevity, namely centenarians, and to assess the relationship between concentrations of TSH and free T(4) (FT4).
DESIGN/SETTING/PATIENTS: We analyzed TSH, FT4, and TSH frequency distribution curves in thyroid disease-free Ashkenazi Jews with exceptional longevity (centenarians; median age, 98 yr), in younger Ashkenazi controls (median age, 72 yr), and in a population of thyroid disease-free individuals (median age, 68 yr) from the U.S. National Health and Nutrition Examination Survey 1998-2002 (NHANES controls).
RESULTS: Serum TSH was significantly higher in centenarians [1.97 (0.42-7.15) mIU/liter] than in Ashkenazi controls [1.55 (0.46-4.55) mIU/liter] and NHANES controls [1.61 (0.39-6.29) mIU/liter] (median, 2.5 and 97.5 centiles) (P < 0.001). The TSH frequency distribution curve of centenarians was relatively similar in shape to controls but shifted significantly to higher TSH, including TSH concentration at peak frequency. The TSH distribution curve of the NHANES control group was superimposable to and not significantly different from the Ashkenazi controls. FT4 was similar in centenarians and Ashkenazi controls, and there was a significant inverse correlation between FT4 and TSH in both groups.
CONCLUSIONS: The TSH population shifts to higher concentrations with age appear to be a continuum that extends even to people with exceptional longevity. The inverse correlation between TSH and FT4 in our populations suggests that changes in negative feedback may contribute to exceptional longevity.
PMID:1915819, NIH, LM, PubMed access to MEDLINE bibliographic citations
Any low calorie diet will depress thyroid function, but food choices can also affect the output of thyroid hormones. Perhaps you have heard of goitrogens, built from the word goiter (a condition in which the thyroid is enlarged, possibly to compensate for the gland’s inability to produce adequate amounts of thyroid hormones) and the stem -gen (producing).
Foods that contain goitrogens include soy products and some of the most healthful vegetables:
- Brussels sprouts
- These are nutritional all-stars – loaded with nutrients, as well as phytochemicals that likely have multiple benefits
A few other foods that are high in goitrogens include:
Some of these foods activate production of antibodies that reduce thyroid function while others depress thyroid peroxidase (TPO), an enzyme known to release iodine during production of thyroid hormones. In either case, the thyroid doesn’t produce as many of the hormones needed to regulate metabolism.This matters little for people with healthy thyroid function. In fact, it may depress metabolic rate in synergy with the beneficial reduction in metabolic rate from a low calorie diet.
Some who have compromised thyroid function may want to limit their consumption of goitrogens or at least consider cooking them, which decreases their goitrogen content. Another possibility is to supplement with the RDA of iodine.
Perhaps most important is to ask yourself if you are having symptoms of hypothyroidism. To make it easy to tell the difference between healthful low thyroid output from following the CR Way and a malfunctioning thyroid, full members may use the chart on the Healthful Hypothyroidism page under Thyroid. If you are concerned, make sure to discuss your thyroid with your doctor.
Just be cautious: It may be easier to pop a pill that to undo unintended damage from it.