Thyroid hormones are a crucial part of a healthy, functioning body. They affect nearly every system in the body and have a direct, relative, effect on metabolic rate and overall health.
In this high stress, highly toxic modern world we live we are seeing more and more people with autoimmune conditions; including hypothyroidism - or Hashimoto’s thyroiditis disease. This illness can be frustrating and debilitating for those who have it and is associated with symptoms that negatively affect quality of life. These include poor digestion, constipation, loss of hair, rapid weight gain - and an inability to lose it, cold hands and feet and water retention.
How you approach an illness like Hashimoto’s is critical for energy and health. In this article we’ll explore whether a low-carb or ketogenic diet is helpful or harmful for people with Hashimoto's disease or other hypothyroid conditions.
What is your thyroid?
The thyroid is a small, butterfly-shaped gland situated at the front of the base of your neck. The best way to describe - and visualise - it, is to think of a small bow tie.
It’s function is to take the mineral iodine and combine it with an amino acid to form thyroid hormones; monoiodothyronine (T1), diiodothyronine (T2), and the two major hormones, triiodothyronine (T3) and thyroxine (T4).
Although the thyroid gland produces more than four times as much T4 as T3, only T3 is considered the "active" form of thyroid hormone responsible for its many effects. In a healthy, functioning human body T4 can be converted to T3.
In your body, T3 is responsible for regulating metabolic rate and calorie burning, controlling body temperature and supporting brain function. T3 also influences heart rate, and plays a significant role in muscle contraction and the retention of your muscle mass (important for losing weight and fasting. We want to lose body fat, while retaining lean muscle).
When it all goes wrong.
A number of glands work together to make sure that your body has the right amount of thyroid hormones circulating in its system.
When thyroid hormone levels are too low, your brain's hypothalamus (which is also responsible for regulating sex and stress hormones as well as adrenal function) releases a hormone which a cascade of signals for the pituitary gland to produce thyroid-stimulating hormone (TSH).
TSH then triggers the thyroid gland to increase its production of thyroid hormones and release them into the bloodstream. On the flipside, if circulating thyroid levels are higher than needed - for instance in an individual with an overactive thyroid, the hypothalamus and pituitary glands release less of these hormones, decreasing the amount of TSH to reduce the amount of thyroid hormone in your bloodstream.
As you can see, there are a lot of moving parts and many ways things can get a bit wonky. There is concern then that reducing carbohydrate levels too low could throw this delicate system out of balance. There is also an argument to be made that too many carbohydrates, especially refined grains and sugar are pro inflammatory and can cause issues for people whose thyroid disease is the result of autoimmunity - or their body attacking itself.
Hashimoto's thyroiditis (also known as Hashimoto's disease) is an autoimmune condition.
Hashimoto's thyroiditis is the most common cause of primary hypothyroidism, a condition in which the pituitary gland is making adequate TSH but the thyroid gland can't produce enough thyroid hormone in response. It is up to 10 times more common in women than in men, affecting an estimated 1-2% of all women. The development of Hashimoto's disease is strongly influenced by genes and environmental factors, hormone shifts postpartum, infections such as the Esptein Barr virus or glandular fever, exposure to certain chemicals and drugs, and nutrient deficiencies.
Carbs and your thyroid.
Decades-old research has shown that very-low calorie diets decrease the level of circulating thyroid hormones in your bloodstream. This means your thyroid has to produce more TSH to keep things running smoothly. Conversely, your body cannot keep producing thyroid hormone at this rate and eventually you have low thyroid hormone production - hypothyroidism.
Low-carb and ketogenic diets have also been found to reduce levels of T3 in the bloodstream. Although a low T3 level alone doesn't indicate hypothyroidism, a recent study suggests that reduced thyroid activity may occur in some susceptible individuals who adopt a very strict low carb diet. Less than 20g per day - i.e the ketogenic diet.
So, does this mean a low carb diet is harmful for people with thyroid conditions?
Potentially. Although we probably need to look more at carb quality and the inflammatory nature of certain carbs, rather than the total number of carbs in and of itself.
A carb-restricted diet based on whole foods may be beneficial for several autoimmune conditions, including Hashimoto's thyroiditis. In fact, many people with Hashimoto's have reported improvement in symptoms after switching to this way of eating. Unfortunately, there is little formal research on keto and low-carb diets for Hashimoto's at this time.
In a 2016 controlled study of 180 people with Hashimoto's disease, one group followed a high-protein, low-carb (12-15% of calories) diet. In addition, this group avoided goitrogens (compounds that interfere with thyroid function), legumes, eggs, dairy products, and gluten.
The control group followed a standard low-calorie diet that didn't exclude any specific foods during the same 3-week time period. By the end of the study the restricted-carb group reported a a 44% decrease in TPO antibodies, a 40% decrease in antithyroglobulin antibodies and a 5% reduction in body weight.
By contrast, the low-calorie group experienced a 9% increase in antithyroglobulin antibodies and a 16% increase in TPO antibodies.
What is interesting is these results occured in a low carb, high fat diet but at carb levels above a strict ketogenic diet. Perhaps also, the improvements happened because of the removal of high inflammatory foods such as grains, dairy and legumes rather than the absence of carbs.
Many clinicians who work with ketogenic diets for weight loss, diabetes, or other conditions recommend that their patients with Hashimoto's avoid a drastically carb-restricted diet of less than 20 grams of total carb per day, in large part this may be because a drastically reduced-carb diet also strips necessary fibre from the diet in people with compromised gut function who would benefit from it.
Endocrinologist Dr. Broda Barnes, who spend decades researching thyroid function and worked with hundreds of thyroid patients, recommends a minimum of 30 grams of net carbohydrate (total carbs minus fibre) for hypothyroid individuals. This amount is similar to the 60-130g total carbs outlined in the study above.
According to registered dietician Franziska Spritzler “If you have Hashimoto's and want to follow a keto diet, it seems wise to avoid extremely severe carb restriction for extended periods of time.
“Similarly, although mild intermittent fasting (such as eating all meals within an 8-hour window) is fine, prolonged fasting of 24 hours or more isn't recommended for people with Hashimoto's because it places undue stress on the thyroid.”
Strategies for supporting your thyroid.
Below are generalised suggestions based on evidence-based practice for the management of thyroid disease. Before implementing any changes it is important to first talk with your healthcare provider. These suggestions are in no way tailored medical advice for individuals.
That being said, there are numerous dietary and lifestyle strategies you can implement to support your thyroid. The first and most important is to reduce inflammation within your body. Hashimotos is an autoimmune thyroid condition where the thyroid gland attacks itself resulting in large amounts of inflammation in your body.
Removing potentially inflammatory foods such as gluten containing grains, dairy, alcohol, sugar, refined grains, coffee and sometimes eggs, nuts, seeds and nightshades can help to heal your gut and support your thyroid.
Essentially this means following an Autoimmune Paleo Diet, or AIP. The idea is to have a period of 1-3 months on a strict AIP diet while implementing gut-healing strategies before reintroducing foods to see if you react to any. This should be done under the guidance of a healthcare professional to ensure you are meeting your nutrient requirements as well as assisting with the reintroduction phase.
Additionally adaptogenic herbs can help with thyroid health. Adaptogens are a unique group of herbal ingredients used to improve the health of your adrenal system, the system that's in charge of managing your body's hormonal response to stress
Adaptogenic herbs to use include;
- Holy basil
Speak to a naturopath about incorporating these herbs as some may not be right for your specific situation.
Alongside an anti-inflammatory diet and adaptogenic herbs, there are key nutrients to focus on for thyroid health. These include, iodine, selenium, zinc and vitamin D. Talk to your health care provider about testing and treatment.
Another factor to consider for optimising your thyroid function is the health of your liver. It is responsible for filtering out mutated hormones - important if your thyroid hormones are out of whack. A person with poor liver function would be quite affected by the hormonal (and neurotransmitter) imbalance and can exhibit symptoms such as hormonal imbalances, inability to fall asleep despite feeling tired, reliance on coffee and other stimulants, digestive discomfort, unexplained weight gain and increased pain with their period. Consider supporting your liver by reducing liver loaders such as coffee, alcohol, sugar. You can also help your body’s natural detox mechanisms with key herbs including;
- Milk thistle
- Broccoli seeds
Lastly, gut health and gut permeability (leaky gut) have been heavily linked to hypothyroidism. Include probiotic-rich foods several times a day. You can include a quality multi-strain probiotic such as prescript-assist or include fermented foods in your diet. These include;
- Miso and tempeh
- Fermented vegetables.
Lastly adjust your diet to support your thyroid. As mentioned, an AIP diet with low-moderate levels of carbohydrate coming from fibre-rich foods will help nourish your thyroid gland.
Include foods high in omega three fatty acids such as salmon, sardines, chia seeds, spirulina and eggs. Other key foods to include are bone broths to support gut health as well as iodine rich foods such as cranberries, seaplants, navy beans, berries, cheese, yogurt and sweet potatoes.
The last point to make about diet is to reduce high goitrogenic foods. Goitrogens are substances that disrupt the production of thyroid hormones by interfering with iodine uptake in the thyroid gland. You don’t need to avoid these foods altogether, however eating them steamed or fully cooked - as opposed to raw - helps reduce the goitrogenic properties of the food.
Goitrogen foods include;
- Bok choy
- Brussels sprouts
- collard greens
If you are concerned about your thyroid levels or health please consult your healthcare provider. If you have any questions at all, please feel free to chat to us. We are here to help.