Is There a Diet and Fitness Plan for Thyroid Cancer?

with Anne McTiernan, MD, PhD, Neil M. Iyengar, MD, and David L. Katz, MD, MPH

Would adjusting your lifestyle reduce your risk of thyroid cancer? It’s possible. By making different choices in the way you eat and increasing your physical activity, it’s likely you can reduce your risk of cancer.1 And, even if you have been diagnosed with thyroid cancer, making these changes may improve your ability to get through treatment, recover, even lead to a better prognosis.

Tuning your diet and upping your fitness can reduce your risk of thyroid cancer.Getting daily physical activity is the best way to prevent cancer, and improve your prognosis after treatment for any cancer, including thyroid cancer. Photo: SDI Productions

As you may already know, the thyroid gland can have an immense effect on your metabolism, given its primary function in producing the T3 and T4 hormones. However, as relates to addressing thyroid cancer, here’s what you need to know.

In considering the potential for diet and exercise to impact thyroid cancer, there are several factors that may influence your risk of developing any type of cancer, in general, and thyroid cancer, in particular:

  • Insulin resistance is associated with a higher risk for thyroid cancer.2
  • Female hormone levels seem to play a role in thyroid cancer influence, although researchers do not understand exactly how.3
  • Excess fat is associated with an increased risk for thyroid cancer.4
  • Increased fat mass around the thyroid gland can increase your risk of thyroid cancer.4
  • Decreased muscle mass is associated with decreased recovery in some cancers.5

From the available evidence, the World Cancer Research Fund/American Institute for Cancer Research produced general recommendations to guide your approach to food and fitness so as to reduce your risk of developing many types of cancer:1

  • Eat plenty of vegetables daily  
  • Choose mostly whole grains
  • Include dried beans (legumes, eg, chickpeas, lentils, edamame, black beans) for protein.
  • Limit processed meats, added sugars, and alcohol.
  • Be physically active and maintain a healthy weight.

Can we go beyond these well-known parameters for healthy living to focus on specific strategies to lower your risk of thyroid cancer? Not just yet. And, this may be fine since just achieving these parameters is a significant enough challenge for most.

Designing a diet regimen [node/60798] that is certain to stave off thyroid cancer, or any cancer for that matter, in every person is still a long way off. This may have more to do with the difficulty in carrying out high quality nutrition studies.

The type of studies best able to deliver clear proof of prevention necessitate randomized control trials; these are complicated and cumbersome, and not really possible when it comes to evaluating the effect that specific foods have on individuals. After all, no group of people eat exactly the same—and who would want to?!

What Would a Thyroid Diet Look Like?

Can we be more prescriptive in terms of dietary practices to prevent cancer and promote recovery following treatment? The European Prospective Investigation into Cancer and Nutrition (EPIC) Trial was a recently published cohort study that was conducted to answer this question.6

“Overall, we found little impact of vegetable or fruit intake on risk of thyroid cancer. However, we did find an increased risk of cancer in people who had large quantities of juices,” said Anne McTiernan, MD, PhD, an investigator at the Fred Hutchinson Cancer Research Center and research professor at the University of Washington Schools of Medicine and Public Health.

“This is not surprising, since people who drink a lot of juice tend to weigh more and excess weight increases risk of thyroid cancer,”7 Dr. McTiernan tells EndocrineWeb.

While the EPIC study did not detect a specific link between vegetable intake and decreased thyroid cancer risk, she believes other data exist to support this relationship. There is a pooled analysis of case-control studies of patients with thyroid cancer,8 in which the data show that higher vegetable intake provides protective properties specifically related to thyroid cancer, she says.

As well, findings from the NIH-AARP Diet and Health Study provide further support for eating vegetables regularly during adolescence as potentially increasing protection against the development of thyroid cancer.9 This is an important insight, says Dr. McTiernan, since these types of studies generally do not examine early-life diets, which is when we expect our behaviors to be more influential in the eventual formation of cancer or not.

What about the anticancer effects from eating cruciferous vegetables—does eating more of these vegetables such as broccoli, kale, cauliflower, arugula, collards, and cabbage, or have any effect on thyroid cancer? Dr. McTiernan says: “eat the broccoli, but only if you like it! All these vegetables from the cruciferous family seem to be a good and necessary addition to a healthy diet.”

Here’s the benefit to reducing your risk of cancers, including even thyroid cancer. During food preparation and in chewing antioxidant-rich vegetables, biologically active compounds—indoles and thiocyanates—are released. These food components have been studied to better understand their health-promoting (ie, anticancer, anti-inflammatory, antiviral, antibacterial) properties.

These vegetables are also a good source of dietary fiber, which you are already likely very aware, will lower your risk of chronic diseases such as heart disease, and diabetes,9,10 in addition to their antioxidant benefits.

There’s the one caveat: cruciferous vegetables contain a goitrogen, which may interfere with the absorption of thyroid hormones. This seems to be of greatest concern in individuals who have an iodine deficiency, which is not a common problem in the United States, and is lessened after cooking these vegetables. This said, this concern is of specific consequence to cancer.

So it seems that the right diet and enough exercise can reduce the risk of thyroid cancer and improve recover? The best answer is “sort of”. While there are very good general guidelines regarding diet, the experts aren’t ready to make prescriptive recommendations for you individually. That is the next step, the experts say.

This is best explained by going back to how we measure strength of the research evidence (SOE), which is essentially the methods researchers rely on to determine the trustworthiness of study results. This is what is necessary in order to have sufficient in the confidence that the data to be able to make claims like “vegetable intake can decrease your risk of thyroid cancer.”

Closer to an Anticancer Exercise Prescription, Diet is Less Clear

While there isn’t yet enough of this robust kind of evidence to describe a specific antithyroid cancer diet, the role of exercise seems a bit clearer.11

"I would bet that exercise could extend the survival rate for people with thyroid cancer,” says Neil M. Iyengar, MD, drawing on the findings from his recently published a review of the research on the potential for exercise to stop cancer.11 While the data are not definitive, Dr. Iyengar tells EndocrineWeb,” we can draw from the evidence we already have, even if not the studies were not specifically performed with thyroid cancer in mind.”

Dr. Iyengar’s bet is supported by the consensus of experts convened by the American College of Sports Medicine who endorse the strong evidence that exercise appears to reduce cancer risk by some 10-20% and improved survival for several different types of cancer.12

While thyroid cancer was not included on that list, it doesn’t rule out possible benefits for this type of cancer, too. Rather, by gaining a better understanding for the mechanisms of thyroid cancer, we can understand whether and which changes in diet and types of exercise are most likely to have a positive effect.

Even so, given the available evidence, Dr. Iyengar believes we are moving towards a future where exercise can be specific and prescriptive in improving cancer incidence and outcomes.

“If we had to choose which form of exercise would be most beneficial, it would be aerobic activities, specifically, interval training,” he says. Interval training is uniquely efficient at managing insulin, controlling inflammation and essentially creating a metabolic profile that is less susceptible to the progression of cancer, including thyroid cancer.

Ideally, resistance training should be added to everyone’s exercise routine to increase muscle density, as this has a direct effect in increasing insulin sensitivity and improving your health at the levels of cell functioning. 

Interval training can also decrease fat tissue, including the adipose tissue that collects around the thyroid gland. When this occurs, it can reduce cancerous conditions by helping to regulate hormone production, namely estrogen and cortisol.

Identifying Lifestyle Patterns that Reduce Thyroid Cancer Risk

Our current methods for measuring SOE favors pharmaceutical or drug studies. We don’t have a reliable way of measuring evidence applied to lifestyle interventions, such as diet and exercise.

The American College of Lifestyle Medicine and the True Health Initiative have launched an effort to tackle this—these organizations recently developed a method to allow researchers to evaluate the evidence specifically for lifestyle interventions—Hierarchies in Evidence Applied to Lifestyle as Medicine (HEALM).12 

Now, researchers like Dr. McTiernan and Dr. Iyengar will have the tools to prove their hunches and potentially prescribe specific forms of exercise and diet that could help prevent and treat specific forms of cancer.

“We know what dietary patterns best support human health, and with the right research applications, and by using techniques like those suggested by HEALM, we can begin designing lifestyle interventions to decrease the incidence of thyroid cancer and increase recovery rates,” says David L. Katz, MD, MPH, founder of the Yale-Griffin Prevention Research Center at Yale University in New Haven, Connecticut and president of the True Health Initiative.

Until then, you’re best bet is to adopt lifestyle behaviors that are not only likely reduce the risks of developing many chronic diseases including diabetes and heart disease, but also lessen your risk of developing thyroid cancer. Such a plan should feature eating mostly plants, little to no red meat, avoiding added sugars and replacing processed foods with whole grains.

If you haven’t already done so, make physical activity a part of your daily routine, and try to include exercises that boost your cardio with some interval training. Some things may be out of your control, but when it comes to lifestyle choices, you are in charge of you.

None of the experts has an financial disclosures that posed a conflict for this article. The author is an employee of True Health Initiative. 


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