Iodine
Iodine is a trace mineral the body uses to make thyroid hormones — the chemical messengers that influence metabolism, energy, temperature regulation and general wellbeing. Although small amounts of iodine are essential, both low and high levels can cause issues, which makes iodine one of the supplements that should never be taken casually.
For most people, iodine needs can be met through food. Supplementation is usually only considered when testing and health history clearly show it is appropriate. If iodine is used incorrectly, it can disrupt thyroid function — especially in people who are already sensitive or have known thyroid conditions.
What It Is
Iodine is an essential mineral needed to make thyroid hormones. These hormones help regulate:
metabolism
energy levels
body temperature
growth and development
cognitive function
Because the body cannot make iodine, we need small amounts from food. Most people meet their needs through a varied diet.
What It’s Used For
Iodine supplements are sometimes considered to support:
thyroid hormone production
energy and metabolism
pregnancy requirements (with professional guidance)
diets low in iodine-rich foods
However, iodine is not a supplement to take for tiredness or metabolism issues without testing or medical input. Many symptoms linked to “low iodine” can have many other causes, making guesswork unsafe.
What the Evidence Says
Research shows that iodine:
is essential for thyroid hormone synthesis
supports cognitive function
contributes to normal growth and development
is particularly important during pregnancy and breastfeeding
However, the evidence also shows:
both deficiency and excess iodine can negatively affect the thyroid
iodine needs vary widely between individuals
certain thyroid conditions become worse with too much iodine
supplements can contain much higher amounts than food, making overdose easy
This is why safe use depends on testing and professional guidance.
When It Can Be Helpful
Iodine may be considered when:
a recent blood or urine test shows low iodine
someone has very low dietary intake, such as avoiding dairy, eggs and fish
a prenatal supplement is being chosen (with clear professional guidance)
thyroid function has been assessed medically and iodine has been identified as appropriate
Iodine should not be taken based on symptoms alone.
Fatigue, low mood, hair changes or temperature sensitivity can have many causes unrelated to iodine.
When Caution Is Needed
Iodine requires greater caution than most supplements.
You should be very careful — and seek professional guidance — if you:
have been diagnosed with a thyroid condition (e.g., hypothyroidism, hyperthyroidism, Hashimoto’s, Graves’)
have ever reacted strongly to seaweed or iodine-containing supplements
are pregnant or breastfeeding (different needs, strict upper limits)
take thyroid medication (iodine can change how the medication works)
take other supplements that affect thyroid function
consume seaweed snacks or kelp powders (these can contain very high iodine levels already)
Very important:
If a supplement label contains more than the recommended daily amount, or if you’re taking multiple products containing iodine, this can easily lead to excessive intake.
Why It’s Not Always the First Step
Many people assume low energy or metabolism changes mean they need iodine, but this is rarely the case. Most UK diets provide enough iodine, and symptoms often relate to other factors such as stress, sleep, digestion or low overall calorie or protein intake.
Before considering iodine supplements, it’s important to explore:
balanced meals with adequate protein
overall energy intake
sleep consistency
stress management
thyroid testing through a GP
whether existing supplements or foods already provide iodine
Supplementation should only follow after clarifying whether iodine levels are genuinely low.
Nutrition Support
Most people can meet their iodine needs through food, including:
white fish (cod, haddock, pollock)
dairy products (milk, yoghurt, cheese)
eggs
shellfish
some seaweeds (in small, occasional amounts)
Supporting digestive health can also help the body use iodine effectively.
Where iodine intake is low due to dietary restrictions, food planning is often the safest and most effective approach before considering supplements.
If You’re Unsure Whether Iodine Is Right for You
If you’re curious about whether iodine could support your health, we can review your diet, symptoms and any recent blood tests together. Because iodine can influence thyroid function in both directions, it’s important to approach supplementation with clarity and confidence — not guesswork.
Prefer to read at your own pace?
I share occasional, practical updates like this, and let people know when something new is published. You’re welcome to leave your email below