Iodine
- Becky
- Jul 23
- 4 min read
Updated: Aug 31
Iodine – The Thyroid Support Mineral
Iodine is a trace mineral that plays a crucial role in maintaining thyroid health, regulating metabolism, and balancing hormones. Without enough iodine, your thyroid gland can't produce the hormones needed to regulate energy, growth, and brain function.
Even though iodine is only required in small amounts, deficiency is still common — especially for people who don't consume seafood or iodised salt.
Why Iodine Is Important
Supports Thyroid Function – Iodine is essential for producing thyroid hormones (T3 and T4), which regulate your metabolism and energy levels. Having sufficient levels of these hormones is crucial to activate and recycle many other vitamins (such as B1, B2, B3, B6, B9, B12, vitamin A and K). See the blog on selenium also.
Brain and Cognitive Health – Adequate iodine is crucial for brain development, particularly in infants and during pregnancy.
Hormone Balance – Iodine plays a crucial role in influencing reproductive health and menstrual cycle regularity.
Immune Support – Healthy thyroid hormones also play a role in immune system function.
Iodine intake during pregnancy and lactation
Iodine is essential for the development of the fetal and infant brain. Pregnancy increases iodine requirements, and to meet these needs, the WHO/UNICEF recommends a daily intake of approximately 250 µg for pregnant and lactating women, compared with 150 µg for non-pregnant adults. The safe intake range is generally considered to be 250–500 µg per day, with an upper tolerable limit of 600–1,100 µg per day depending on regional guidelines.
Importantly, recent studies have shown that iodine's effect on neurodevelopment follows a U-shaped curve, indicating that both mild deficiency and excessive intake can impair outcomes. Data from the PINK cohort suggest that maternal intakes below 220 µg per day or above 391 µg per day are linked to reduced verbal IQ and language skills in children.
Excess iodine can also interfere with thyroid hormone synthesis via the Wolff–Chaikoff effect, potentially causing hypothyroidism in mother and child. These findings emphasise the importance of maintaining iodine intake within a safe and balanced range during pregnancy and lactation.
Recommended Daily Intake (RDI)
• Adults: 150 mcg/day
• Pregnant Women: 220 mcg/day
• Breastfeeding Women: 290 mcg/day
(Note: Too much iodine can disrupt thyroid function, so balance is key.)
Signs of Iodine Deficiency
Iodine deficiency can lead to an underactive thyroid (hypothyroidism), which slows down many body functions. Common symptoms include:
• Fatigue or low energy
• Weight gain
• Dry skin and hair loss
• Brain fog or poor concentration
• Swelling at the base of the neck (goitre)
• Sensitivity to cold
Top Food Sources of Iodine (with Portions & Amounts)
Seaweed (kelp, wakame, nori): 1g dried kelp = 150–300 mcg (varies by type)
Cod: 100g cooked = 100 mcg
Shrimp: 100g cooked = 35 mcg
Yoghurt (plain): 1 cup (250ml) = 75 mcg
Eggs: 1 large egg = 24 mcg
Iodized salt: ¼ teaspoon = 70 mcg
Itsu Crispy Seaweed Thins 5g pack = 92 mcg
Available from Amazon here (paid link).
(Tip: Seaweed is extremely rich in iodine, so a small serving is plenty.)
Why Keeping a 5-Day Food Diary is So Helpful (Especially with a Free App Like Cronometer)
If you've ever wondered whether you're getting enough vitamins and minerals from your diet, keeping a food diary for just 5 days can be a real eye-opener. Using a free app like Cronometer makes the process simple and surprisingly insightful.
Cronometer doesn't just track calories — it gives you a complete nutritional breakdown of the food you eat each day. You'll quickly see where your diet is strong and where you might be missing out on important nutrients like B12, magnesium, or iron.
One of the best things about using an app like this is that you can experiment. Try swapping in nutrient-dense foods — such as chicken liver, beets, or romaine lettuce — and see how even small changes can dramatically improve your nutrient intake.
If you're using my example one-day meal plans for specific vitamins and minerals, keep in mind: they're just examples to show what's possible. Cronometer helps you take it a step further by tailoring things to your own diet, preferences, and needs.
Tracking your eating habits for just 5 days can give you a clearer picture of how they support your health — and where a few clever tweaks can make all the difference.
Example Meal Plan to Meet the RDI
Here's an example of how to get ~150–200 mcg of iodine in a single day:
Breakfast:
2 boiled eggs (48 mcg)
1 cup yoghurt (75 mcg)
A sprinkle of iodised salt on avocado toast (15 mcg)
Lunch:
Mixed greens salad with 100 g shrimp (35 mcg)
Snack:
A few seaweed sheets (20–30 mcg)
Dinner:
Grilled cod (100 g – approx. 100 mcg)
Steamed vegetables with a light pinch of iodised salt (5 mcg)
Total: ~200–230 mcg iodine
Goitrogens and antagonists:
Foods like soy, cruciferous vegetables (such as cabbage and broccoli), and related supplements (sulforaphane) can interfere with your iodine uptake.
Consume cruciferous vegetables in moderation (1-3 servings/day).
Be aware that taking sulforaphane may increase your need for iodine.
Additionally, be mindful that altering your salt intake, especially if you use iodised salt, may require compensating for the loss of iodine.
Additionally, fluoride, chlorine, and bromine (present in water/swimming pools) can all interfere with iodine function.
Iodine Supplements – Do You Need Them?
Most people can meet their iodine needs through a balanced diet, particularly if they include seafood or iodised salt.
However, vegetarians, vegans, or people on dairy-free diets may be at risk of deficiency and could benefit from supplements or seaweed products.
Be cautious with kelp tablets or liquid iodine drops — they can contain very high levels of iodine that may overstimulate or block thyroid function.
The iodine should be either Sodium or Potassium Iodide, not Lugol's Iodine.
We use this version from Amazon (paid link):
Iodine 150mcg 120 Tablets | Max Strength Potassium Iodide
Symptoms of over-supplementing with Iodine are generally flu-like symptoms, drowsiness, brain fog following Iodine supplementation, and a drop in TSH below 0.5.
If you feel like you might be iodine-deficient, try increasing your iodine intake from foods or supplements or decreasing any antagonists.
If you have Graves or Hashimoto's, have your doctor carefully monitor your response to any change in iodine intake.
For more information, please visit
This information is for educational purposes only and is not medical advice
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