Hashimoto's thyroiditis (HT) is an autoimmune disease, in which immune cells (T-
lymphocytes) mount an attack on cells of the thyroid gland, which frequently leads to
hypothyroidism1. HT is not only the most prevalent autoimmune thyroid disease (ATD),
but it is also the most common autoimmune disease in the world, with a prevalence of
9,460 per 100,000 people1, affecting more women than men1.
As with other autoimmune diseases, part of the risk of contracting HT is genetic1. It is the
interaction between one's genotype and several environmental factors that results in
autoimmune disease. Although to our knowledge there are no trials investigating the role
of specific diets on HT, several lines of evidence suggest that the Paleo Diet could prove
beneficial:
1. The Paleo Diet doesn't include gluten containing grains, such as wheat, barley, rye and
oats2. This is very important, since these are the main triggers of another autoimmune
disease, called celiac disease (CD)2, 3. CD carries an increased risk for other auto-immune
diseases including ATD3-11, which may be explained by the fact that these conditions
share similar HLA haplotypes (genetic markers)12. The association is so strong that
researchers from Italy concluded that anyone showing evidence of ATD should also be
screened for CD8.
2. By being a grain and legume free diet, the Paleo Diet minimizes the intake of certain
dietary lectins that have been shown to damage intestinal cell walls13. This damage allows
passage of bacterial and dietary proteins (such as yeast and milk proteins, which are also
not part of the Paleo Diet) into the blood stream that should not be allowed there.
These proteins' amino acid sequences resemble amino acid sequences in our body's
organs and tissues13. Immune cells "read" the amino acid sequences on the bacteria and
dietary protein, and may begin to associate similar self-proteins with these foreign
substances, thus attacking both the bacteria or dietary protein and our own tissues13.
Although to our knowledge there are no studies investigating this chain of events in ATD,
studies from other autoimmune diseases such as rheumatoid arthritis13 suggests that this
may also be the case with ATD.
3. The Paleo Diet decreases the Omega 6/Omega 3 ratio, which tends to calm down
inflammation14, 15. The characteristic inflammation of auto-immune diseases typically
aggravates these conditions, including HT1.
4. The Paleo Diet provides a generous amount of various antioxidants16 (such as vitamins
C and E, carotenoids and various phytochemicals present in fruits and vegetables) and
nutrients needed for optimal functioning of endogenous antioxidant enzymes (such as
manganese, zinc and copper, needed for the superoxide dismutases to perform their
antioxidant functions, and selenium - Se, which maximizes glutathione peroxidase
activities ). This is important, since oxidative stress is suspected of being involved in
ATD17.
Moreover, selenium deficiency plays an important role in autoimmune thyroid diseases18-
21, such as HT22. In fact, some trials have shown that selenium supplementation in doses
higher than 100 mcg/day decreases serum concentrations of thyroid peroxidase antibody
(a marker of ATD)20. It should be mentioned that selenium deficiency is likely to occur in
CD18, due to malabsorption, which is one of the characteristics of these diseases. Hence
there is one more reason for ATD patients to avoid gluten-containing foods.
Importance of Vitamin D
Another important aspect for ATD patients is optimization of vitamin D status. Vitamin D
insufficiency is a common condition, but was very rare among our hunter-gatherer
ancestors living in Africa, who received sufficient ultraviolet radiation from the sun to
synthesize all the vitamin D3 they needed.
Numerous studies show that vitamin D insufficiency can be involved in the pathogenesis
of autoimmune diseases 23, such as RA, multiple sclerosis and type 1 diabetes. As
expected, preliminary research suggests that it may also be involved in HT24,25.
Therefore, it may be worthwhile for anyone with HT or any other autoimmune disease to
measure 25OHD3 in the blood, and to try to get the levels between 30-60 ng/ml (75-150
nmol/L)23.
If you assume that for each 40 IU of vitamin D3, you can increase blood levels of 25OHD3
by 0.28 ng/ml (0.7 nmol/L)26 then you can calculate how much supplemental vitamin D to
take. For instance, if your 25OHD3 level is 19 ng/ml, and you want to reach 33 ng/ml, you
could easily estimate how much Vitamin D3 you'll have to take:
(33-19)x40/0. 28 = 2000 IU
Dietary Recommendations for Hashimoto's
In summary, if you have HT or another autoimmune disease (or if you want to avoid
autoimmune disease in the future), you may benefit from adopting a Paleolithic type diet,
with no grains, dairy, legumes, or yeast containing foods. You may also want to
supplement to get adequate omega 3 fatty acids (EPA and DHA) and vitamin D3, and those
living in a region of the world where soils are depleted in selenium27-31 may want to
supplement with selenium also. Recent research by Dr. Cordain also suggests that
autoimmune patients may wish to avoid tomatoes and egg whites, which could also be
involved in autoimmunity. Fully referenced reports on these two foods are available in the
How to Treat and Prevent M.S. with Diet program, listed below.
References are available at
http://www.ThePaleo Diet.com/ v4n22.shtml.
