For such a small organ, the thyroid holds sizable sway over your body. The little butterfly-shaped hormone regulator near your throat can speed or slow metabolism, increase or decrease your heart rate, affect your energy levels, maintain your body temperature, and more.

Considering its power over so many bodily processes, you want to keep your thyroid functioning well. And, fortunately, there are a variety of lifestyle hacks to ensure this endocrine organ keeps chugging along. Unsurprisingly, many revolve around what you eat.

If you already have problems with your thyroid, choosing the right foods can help this powerful gland find balance. On the flip side, if your thyroid is currently healthy, routinely eating a poor diet could lead to hormone disruption. “Inadequate intakes of micronutrients, including zinc, magnesium, and vitamin A, may impair thyroid function and lead to hypothyroidism,” says Lisa Andrews, M.Ed., R.D., L.D., author of The Complete Thyroid Cookbook. “Poor intake of iodine, particularly in women of childbearing age, is also a risk factor for thyroid dysfunction.”

So, what does eating for a healthy thyroid look like? It starts with limiting the following five foods and replacing them with more nourishing options.   

1. Ultra-Processed Foods

This probably doesn’t come as a shock, right? We’ve all heard for years that ultra-processed foods (those with high amounts of added sugars, preservatives, artificial flavors, and colors) are bad news for health. After all, eating lots of super-processed products has been linked with health harms like weight gain and cancer, among others.

You can add thyroid harm to that list, as well. A 2022 study published in Food and Function linked eating a diet higher in ultra-processed foods with a higher risk of subclinical hypothyroidism in adults. “Intake of more processed foods may also reduce the consumption of vitamins and minerals, including those that are needed for normal thyroid function,” says Andrews. “I advise people with hypo- and hyperthyroidism to limit their consumption of processed foods.” As much as possible, craft your meals and snacks around whole foods like lean proteins, whole grains, fruits, and vegetables. (Check out this guide to cutting out highly-processed foods in two weeks for some extra help.)

2. Foods with Added Sugar

Sorry to be the bearer of bad news, but high-sugar desserts aren’t a friend to your thyroid, either. “The thyroid helps regulate glucose metabolism, so people with thyroid conditions are at a higher risk of type 2 diabetes. This is because impaired thyroid function (both hypo- and hyperthyroidism) may influence insulin levels and, in turn, alter carbohydrate metabolism,” explains dietitian Jeanette Kimszal, R.D.N, N.L.C., of Thyroid Nutrition Educators. “If someone with a thyroid condition consumes foods that increase insulin levels, doing so could lead to metabolic health conditions.”

If you have a thyroid condition, Kimszal advises staying mindful about how much of the sweet stuff you’re taking in. “Stick to less than 15 grams (about 3.75 teaspoons) of added sugar per day,” she recommends. Consider opting for plain, unsweetened versions of foods (think plain Greek yogurt versus parfait) so that you can better control that total sugar count. And don’t count out whole fruit, a fine option since it also offers fiber. (Berries and apples make great high-fiber snacks.)

There’s currently no strong evidence to show that eating sugar can cause thyroid problems in people who don’t already have them, so this advice is particularly relevant for those with existing thyroid concerns. That said, even if your thyroid is in great shape, it’s best to be mindful of sweets for general health. (For reference, here are nine signs you might be going overboard.)

3. High Amounts Of Cruciferous Vegetables

Wait a minute, aren’t broccoli, cabbage, cauliflower, and kale superstars of healthy eating? Definitely! But there’s a catch for people with thyroid issues. A nutrient called sulforaphane, which cruciferous veggies are famous for, is the reason they’re in the hot seat here. 

While sulforaphane is generally quite beneficial (according to Andrews it works to protect the colon and long-term health), high amounts of it could actually be harmful to thyroid function. Since 70 to 90 percent of the sulforaphane we consume is excreted through urine, people with perfectly healthy thyroids don’t need to stress about going all in on the cauliflower. (In fact, research suggests you’d have to eat a pretty exorbitant amount of cruciferous vegetables to consume enough sulforaphane to potentially run into trouble.)

Still, if you have existing thyroid issues, Andrews advises keeping cruciferous veggie consumption moderate. A serving or so per day should be a-okay.

Read More: 6 Ways to Sneak More Veggies Into Your Diet

Another reason people with thyroid problems might want to be mindful of their Brussels sprouts consumption: These veggies might influence iodine levels, which have a significant impact on thyroid function. “There is evidence that cruciferous vegetables can interfere with iodine metabolism, and iodine is needed for thyroid hormone production,” explains endocrinologist Rekha Kumar, M.D., M.S., head of medical affairs at weight-care company Found. Of course, if you’re concerned about how your cruciferous veggie consumption impacts your thyroid, check in with your healthcare provider. 

4. Coffee

Hyperthyroidism is known for ramping up feelings of anxiety and jitteriness—so, if you have an overactive thyroid, depending on your sensitivity to caffeine, adding coffee to the mix might not be a great move. “Since people with hyperthyroidism often have a higher heart rate, it is important to avoid anything that will stimulate the body, including coffee,” says Kimszal. 

An elevated heart rate might not be the only downside of tossing back a few lattes for this crew.  “Caffeine is also thought to affect adrenal function due to its ability to elevate cortisol levels,” Kimszal adds. “This can be harmful to anyone who has weak adrenals, which are common in those with thyroid conditions.” For a coffee alternative, consider green tea, which contains some, but much less, caffeine.

5. Deli Meats

How about swapping out that deli ham in your lunchtime sandwich for some smoked salmon or chicken breast? Deli meats may pose problems for your thyroid. “In addition to a higher risk of cancer, diabetes, and heart disease, processed meat contains nitrates, which increase the risk for thyroid cancer,” says Andrews. 

Minimally processed sources of red meat—such as ground beef or steak—on the other hand, are less of a concern. “Moderate intake of lean red meat is acceptable and even advised in individuals with thyroid disease, as iron deficiency is more common in these people,” Andrews notes. According to Kimszal, iron is a power player for thyroid health in just about everyone. “Iron is needed to convert T4 to T3, the active thyroid hormone,” she says. “A deficiency in iron may lead to hypothyroidism.”

Wait, What About Gluten?

Judging by thyroid health message boards and social media groups, you might be convinced that gluten is an absolute no-no if you have a thyroid condition. But it’s worth mentioning here that the science isn’t as settled as it might seem online.

“There is not sufficient evidence that all people with thyroid issues should avoid gluten,” says Kumar. Where the confusion often stems from: Some thyroid disorders have overlap with celiac disease, the autoimmune condition that requires eliminating gluten. One prominent example: Hashimoto’s disease, an autoimmune condition in which the immune system attacks thyroid cells, causing hypothyroidism. “Hashimoto’s in itself is not related to gluten, but people with Hashimoto’s are more likely to have celiac disease,” Kumar explains.  

Read More: ‘How Going Gluten-Free For Celiac Disease Changed My Life’

That said, “going gluten-free seems to benefit the inflammation that accompanies most autoimmune thyroid conditions,” Kimszal notes. “For Hashimoto’s, it has been recommended to reduce antibody production.”

Also, the reason why some people who have thyroid issues that aren’t Hashimoto’s might feel better when scaling back on gluten-heavy bread, pasta, and cereals doesn’t really have to do with the gluten itself. “Many people feel better when they reduce their gluten intake because they are unintentionally reducing processed carbohydrates,” says Kumar. Remember, highly-processed foods don’t do a thyroid any favors.

Then again, it’s easy to lose out on important nutrients when you remove wholesome gluten-containing foods from your diet. So before you take the GF plunge, be sure to speak to a diet professional. “It is best to work with a registered dietitian who can help you go gluten-free without losing any nutrition,” Kimszal says.