Sugar, Artificial Sweeteners, and Thyroid Problems

Thyroid disease affects your body's metabolism, and if you have a thyroid condition, you may have been advised to consume sugar in moderation. While this is good advice, using sugar substitutes instead of regular table sugar may not be the answer.

Sugar, Thyroid Disease, and Diabetes

If you have thyroid disease, you are at an increased risk of developing type 1 diabetes or type 2 diabetes. And if you have diabetes, you are at increased risk of thyroid disease. When these conditions occur together, they can also exacerbate each other's symptoms and interfere with treatment.

The complex links between these two disorders are not fully understood. The connection is believed to be related to multiple factors, including an increased tendency to develop an autoimmune disease, glucose level irregularities, and alterations in fat metabolism.

With the inherent risk of developing one condition if you have the other, there are some recommended prevention strategies, the most important of which is making sure that your blood glucose levels stay between 70 and 105 mg/dL. Avoiding excess added sugar and fructose is an important part of keeping your glucose in the recommended range.

Your weight can be affected by thyroid disease and diabetes, and being over- or underweight can trigger either condition. As such, weight control is another important strategy when it comes to the prevention of these conditions.

Natural Sugars

Fruit and vegetables are natural sources of sugar. Whether or not their effect is the same as added sugar in terms of one's risk of thyroid disease was the subject of a European study.

Researchers followed 748 volunteers for a period of 14 years to evaluate the impact of fruit and vegetable intake on thyroid disorders. The research found that fruit and vegetable consumption did not protect or increase the risk of thyroid cancer or thyroid disease—it had no effect at all in this regard.

High rates of fruit juice consumption, however, was associated with a slight increase in thyroid disease. This could have been due to exposure to pesticides or added artificial sweeteners.

Artificial Sweeteners

The research, conducted by investigators at Mount Sinai Hospital in New York City, evaluated 100 people who had been positively diagnosed with hypothyroidism. What they found was that the use of artificial sweeteners within this population—including aspartame (Equal, NutraSweet) and sucralose (Splenda)—correlated with elevated levels of thyroid stimulating hormone (TSH). Increased TSH levels are considered indicative of hypothyroidism.

Among the study participants who had HT, 53% reported using the equivalent of 3.5 packets of artificial sweetener per day, which was four times the rate seen in people without HT. This suggests that the amount of sugar substitute used by the participants could have played a role in the development of HT.

In the study, two of every three who had subsequently stopped using artificial sweeteners had a complete reversal of their HT. Their thyroid antibodies gradually returned to normal, and they were even able to stop their hormone replacement medication. This response to discontinuing the sweeteners supports the idea that artificial sweeteners may play a role in thyroid disease.

The experiment was not replicated in humans, but a newer research study on rats showed a profound effect of sugar on thyroid function. A group of rats was not fed any sugar, while other groups of rats were given different types of sugar substitutes. The rats who were fed artificial sweeteners developed altered thyroid activity, and their thyroid activity differed based on the type of sugar substitute they received.

While rat studies certainly do not translate to human responses, the results provide some insight.

A Word From Verywell

Moderation is key when it comes to the use of any sweetener, but particularly when it comes to artificial products, which are often difficult for the body to metabolize and eliminate efficiently.

If you have thyroid disease, a well-balanced diet is important, and there are some special considerations that you need to be aware of because certain foods can exacerbate thyroid disease.