How does diet affect thyroid function?

Diet and the thyroid: which nutrients are essential?

The thyroid requires several nutrients to ensure the production and metabolism of thyroid hormones (1).

This is why several nutritional factors are particularly important:

• ensuring an adequate intake of iodine (2);
• ensuring an adequate intake of selenium (3);
• do not neglect zinc, tyrosine and other micronutrients (4);
• favouring a varied diet that provides all the necessary nutrients;
• where necessary, use targeted supplementation or formulations combining several key nutrients.

These various nutrients work together to support thyroid function.

However, it is important to bear in mind that none of them can, on its own, support the thyroid’s overall function.

Nutrients essential for healthy thyroid function

Iodine, a nutrient essential for the production of thyroid hormones

It is worth noting that iodine is a trace element that plays a fundamental role in thyroid function.

It contributes to the normal production of thyroid hormones and the normal functioning of the thyroid gland.

In fact, the thyroid gland captures iodine circulating in the blood via a specific transporter located on its cells.

An enzyme, thyroperoxidase, then combines this iodine with the tyrosine residues of thyroglobulin, a storage protein, to produce the thyroid hormones T3 and T4 (5).

An adequate intake of iodine is therefore necessary for this process to function properly.

Conversely, excessive intake can lead to thyroid disorders, particularly in people with a pre-existing thyroid condition or who have previously experienced iodine deficiency (6).

This risk remains very low, however, as it is linked to excessively high iodine intake. Under normal circumstances, any excess iodine not used by the thyroid is excreted in the urine.

To meet daily iodine requirements, the main dietary sources to be aware of are:

• sea fish;
• seafood;
• seaweed;
• iodised salt;
• egg yolks and milk (7).

Targeted supplementation may also be considered to increase iodine intake, with the recommended daily intake estimated at between 100 and 200 µg/day.

Discover Potassium Iodide, an iodine supplement with optimal bioavailability, designed to meet the recommended daily intake of iodine.

Selenium: a key factor in thyroid function

Selenium also contributes to the normal functioning of the thyroid.

It is involved in the conversion of thyroxine (T4) into triiodothyronine (T3), the active form of the thyroid hormone.

It is also used to produce selenoproteins, enzymes found mainly in the thyroid. These enzymes have antioxidant properties and protect thyroid cells (8).

A selenium deficiency can therefore disrupt this conversion and lead to a hormonal imbalance. This is why many studies are now looking into the benefits of selenium for thyroid health.

In terms of diet, selenium is mainly found in:

• Brazil nuts;
• fish;
• seafood;
• eggs;
• meat.

When diet alone is not enough, a dietary supplement can help to top up these levels.

Discover Selenium, a supplement that provides L-selenomethionine, a form of selenium which, according to some research, may help maintain stable selenium levels.

Zinc, iron and other micronutrients: often overlooked players

As well as iodine and selenium, other micronutrients are necessary for the optimal functioning of the metabolic processes involved in the biosynthesis of thyroid hormones.

For example, zinc is one of the micronutrients being studied for its link to thyroid hormone metabolism (9).

It is thought to play a role in the structure of certain receptors and enzymes involved in the action of these hormones, as well as in the regulation of TRH and TSH (hormones of the brain-thyroid axis).

Research into the role of zinc in regulating thyroid hormone metabolism is ongoing.

Within our bodies, iron is necessary for the proper functioning of certain enzymes essential for the production of thyroid hormones.

One study suggests that iron deficiency reduces the synthesis of these hormones as well as the effect of iodine supplementation, whilst iron supplementation enhances it (10).

Meanwhile, B vitamins, particularly vitamins B2, B9 and B12, have been linked to healthy thyroid function in a study involving 387 people (11). This study highlights a strong association between micronutrient levels and thyroid markers.

These various micronutrients are naturally found in a variety of foods:

• oysters;
• seafood;
• meat;
• pulses;
• eggs.

When the diet does not provide all the necessary micronutrients, supplementation may be considered.

Discover Advanced Zinc Lozenges, a supplement containing zinc bisglycinate, a form of zinc recognized for its excellent absorption and good digestive tolerance.

Tyrosine, a precursor to thyroid hormones

Thyroid hormones are synthesised from iodine, but also from an amino acid: tyrosine.

As we have seen above, the thyroid needs tyrosine to produce the hormones T3 and T4.

Tyrosine is a non-essential amino acid. This means that the body is able to produce it itself from another amino acid, phenylalanine (11).

It thus differs from minerals such as iodine or zinc, which must be obtained from the diet.

A sufficient protein intake is nevertheless beneficial, as it provides the body with the phenylalanine required for this synthesis (12).

Several protein-rich foods can support this process:

• fish;
• meat;
• eggs;
• dairy products;
• pulses.

However, when there is insufficient tyrosine in the diet, and metabolic demand exceeds the body’s ability to synthesise it internally, supplementation may be beneficial.

Discover N-Acetyl L-Tyrosine, a dietary supplement containing tyrosine, the amino acid that the body synthesises itself from phenylalanine.

Why does no single nutrient act on its own?

No single food or nutrient, on its own, can support normal thyroid function.

A varied diet remains the best way to meet all your micronutrient requirements.

Overall nutritional quality also matters.

Above all, it is the diversity and quality of the diet as a whole that contribute to the thyroid’s proper functioning.

Protein intake also plays an important role, as it provides the amino acids needed to produce thyroid hormones.

More broadly, an overall balanced lifestyle, sleep, physical activity and stress management all influence the proper functioning of the thyroid and the body as a whole.

Thyroid function therefore depends on a complex interplay of nutritional and environmental factors.

Can a single formula combine several key nutrients for the thyroid?

When dietary intake is insufficient or unbalanced, some people may seek additional nutritional support through supplementation.

A dietary supplement is never a substitute for a balanced diet, but it can help to top up nutrient intake where necessary.

Some formulations therefore combine several nutrients involved in normal thyroid function, such as iodine, selenium, zinc and other nutritional co-factors.

Discover Natural Thyro Formula, a supplement formulated from a blend of nutrients and plant extracts selected to support normal thyroid function.

Diet and the thyroid: mistakes to avoid

It is important not to believe certain misconceptions that circulate about diet and the thyroid:

• believing that a single food can ‘stimulate’ the thyroid;
• consuming large amounts of seaweed or iodine-rich supplements without professional guidance;
• neglecting the overall balance of your diet;
• focusing on a single nutrient whilst neglecting other cofactors.

To support healthy thyroid function through diet, the main aim is to maintain an appropriate and balanced intake of nutrients.

A varied diet therefore remains the primary means of supporting normal thyroid function.

Dietary supplements can then be incorporated into a holistic nutritional approach when used appropriately.