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This post is the ninth installment in my ten-part Minerals and Your Thyroid series, where I’m highlighting eight thyroid-supportive minerals (iodine is two parts) and one troublemaker: fluoride.

Prior posts: Calcium, Copper, Iron, Iodine (Part 1, Part 2), Magnesium, Manganese, Selenium

Zinc symbol: Zn
Atomic number: 30

As I mentioned in the introduction to this series, when it comes to thyroid health, Dr. Richard Shames states, “More important than vitamins are minerals.” He says that minerals are “absolutely crucial to thyroid function, especially copper, zinc, and selenium.”

Adequate zinc levels help to:

• Increase Free T3, the unbound, available form of the active thyroid hormone, T3
• Lower RT3, the “anti-T3 hormone”
• Lower TSH
• Convert T4 to T3
• Source

[I thoroughly address optimal thyroid nutrition in my best selling cookbook, The Essential Thyroid Cookbook: Over 100 Nourishing Recipes for Thriving with Hypothyroidism and Hashimoto’s. The educational component of the cookbook details not only thyroid-supportive minerals, but also vitamins and amino acids that help to optimize thyroid function. The mouthwatering recipes are chock full of these supportive nutrients.]

Last week, I explained how I’d dubbed selenium “the thyroid triple play.” Now I’m thinking that zinc needs the title of “the thyroid quad play.” 

Vitamins are important for thyroid function, no doubt – especially A (as beta-carotene), the Bs, C, D, and E. But as we come to a close with this series (next week is the last Minerals and Your Thyroid post, where I’ll focus on deleterious fluoride), Dr. Shames’ claims about the importance of minerals is abundantly clear (not that I ever doubted the wise man).

And many with hypothyroidism are zinc-deficient.

According to Dr. David Brownstein, “The serum levels of zinc are positively correlated with the levels of the active thyroid hormone, T3. My experience has clearly shown a decrease in the conversion of T4 into T3 in zinc-deficient individuals.”

That Copper/Zinc Thing
In my copper post, I referenced zinc frequently, given that there is such an important relationship between these two minerals.

I’m just going to copy and paste some of what I said in that post. Why recreate the wheel, right?

According to Dr. Ann Louise Gittleman, “Copper and zinc tend to work in a seesaw relationship with each other. When the levels of one of these minerals rise in the blood and tissues, the levels of its counterpart tend to fall. Ideally, copper and zinc should be in a 1:8 ratio in favor of zinc. But stress, overexposure to copper, or a low intake of zinc can throw the critical copper-zinc balance off, upsetting normal body functioning.”

This imbalance can slow thyroid function. Dr. Gittleman goes on to say that a copper-zinc imbalance can not only keep us weight loss resistant, but can also thwart that important T4 (the inactive form of thyroid hormone) to T3 (the active form of thyroid hormone) conversion.

When the thyroid is underactive, it can inhibit your digestive system from absorbing those above-mentioned, “critical” thyroid minerals – copper, zinc, and selenium. This is a classic negative feedback loop. You need these minerals for proper thyroid function, but low thyroid function can keep you from absorbing them.

A copper/zinc imbalance can also lead to:

• Compromised immune function
• Sun sensitivity
• General skin sensitivities
• Depression
• Anxiety
• Extreme fatigue
• Panic attacks
• Acne
• Psoriasis
• Migraines
• Eczema
• Attention deficit
• White spots on fingernails
• Severe PMS
• Extreme cases: schizophrenia 

Interestingly, not only are copper and zinc minerals, but they’re also considered neurotransmitters – chemical messengers that keep our brain cells communicating with one another.

Zinc and Hair Loss
While hair loss is often multi-factorial (I should know), a zinc deficiency is a primary factor to consider. (When it comes to minerals, low ferritin (your iron storage protein) can also be a major culprit.) 

There are many manifestations of hair loss, from the various types of alopecia (autoimmune), to diffuse thinning from low thyroid function, to other hormonal issues such as testosterone imbalances, to insufficient stomach acid.

But a zinc deficiency in the presence of low thyroid function is a double whammy, especially for those with any type of alopecia. So often, increasing zinc intake with supplementation or zinc-rich foods (see list below) and supporting the thyroid can help with not only slowing the loss, but also with regrowth.

Zinc (and manganese) may interfere with iron absorption. So while zinc and iron are both important for hair growth, this is another “not too much, not too little” situation where over-supplementation with zinc could lead to malabsorption of iron. Dr. Shames recommends 25 milligrams of zinc daily.

Other benefits of zinc:

• Supports healthy immune system
• Helps with protein metabolism
• Helps to optimize pathways of detoxification
• Hastens would healing
• Reduces susceptibility to infections
• Supports healthy brain function
• Promotes insulin sensitivity
• Can shorten the duration of the common cold
• Supports testosterone production
• Helps to regulate ovulation and your monthly cycle

Zinc and Your Adrenals
Really now, can we conclude this post on minerals without mentioning the adrenals, as we have in nearly all of the other posts in this series?

My blanket statement for this series should be: Excess cortisol, one of our adrenal stress hormones, can deplete minerals. (I believe that excess cortisol can deplete most nutrients.)

Here’s a classic pattern for those with adrenal dysfunction that zinc has been shown to help with…

Many have high nighttime cortisol, which is the opposite of what should be happening. Cortisol should be highest in the morning, sometime between 6:30 am and 8:30 am, which is what allows us to feel alert and ready for the day.

Then, after dropping throughout the day, cortisol should then take a dip late evening, allowing us to feel tired, relaxed, done with our tasks and to-dos, and ready for bed. It should stay low all night, then spike again in the morning.

But many have what’s called “the cortisol switch.” Their cortisol has gone rogue, whereby morning cortisol is low and evening cortisol is high.

I always ask my clients, “Are mornings rough? Do you have a difficult time rousing? Do you not really ‘wake up’ until around 10:00 am? Do you slog through the day, only to get a second wind, a burst of energy around 9:00 pm? Then you’re wound up, can’t go to bed at a reasonable time, then lie there, trying to go to sleep?”

Most people say, “YES!” That’s me!

There are multiple ways to address this switch-a-roo, but get this. Zinc helps to lower bedtime cortisol.

According to this study, “Zinc acutely and temporarily inhibits adrenal cortisol secretion in humans.”

The recommendation is to take zinc about an hour prior to bedtime to help lower cortisol and thus help you fall asleep and stay asleep.

This is but one approach in addressing high evening cortisol cycle; it’s not recommended as a long-term strategy, given that ongoing zinc supplementation can lower copper.

Foods rich in zinc include: spinach, sea vegetables, mushrooms, beef, chicken (dark meat), turkey (dark meat), lamb, pork, oysters, crab, lobster, scallops, natto, peanuts, adzuki beans, garbanzo beans, kefir, yogurt, sesame seeds, pumpkin seeds, almonds, cashews, amaranth, buckwheat, millet, oats, chili powder, asparagus, and…dark chocolate (!).

Red meat and seafood are said to be the best of the best sources of zinc. Therefore, vegetarians are much more prone to zinc deficiency and often need supplementation – about 50% higher doses. 

You want to avoid foods that deplete zinc, like sugar, refined carbohydrates, alcohol, and caffeine.

Important note for this whole Minerals series: You may see some slight discrepancies in the list of foods in this post and the list of foods in my thyroid- and immune-supportive nutrition chart (which you can download for free here). This is because for the chart, we created a ranking system. If each thyroid- and immune-supportive food didn’t have a broad enough nutritional spectrum such that it represented enough nutrients, it didn’t make the cut. In other words, the list in this post may be slightly more inclusive.