The information in this article is based on personal experiences and general knowledge, not professional medical advice. Always consult with a healthcare provider before making any changes to your diet, lifestyle, or treatment plans. This content was created with the assistance of AI tools and should not replace advice from a licensed professional.
How much nori, dulse, or arame can provide the recommended daily allowance for iodine?
Dairy milk provides about a quarter to half of the daily iodine requirement in the United States, though milk itself contains very little natural iodine. The iodine content in milk primarily comes from iodine-based disinfectants, like Betadine, used on the teats during milking. These disinfectants leach iodine into the milk.
Unfortunately, most plant-based milks on the market aren’t fortified with iodine. Fortified soy milk is the healthiest option among plant-based milks, but even if enriched with iodine, concerns remain about the effects of soy on thyroid function. While some research has suggested that soy might influence thyroid function—especially in animal studies—people in Asian countries have consumed soy for centuries without noticeable thyroid issues. For most people with normal thyroid function, soy appears safe. However, soy may interfere with the absorption of thyroid medication like Synthroid, which is why it’s recommended to take such medications on an empty stomach. It’s important to ensure adequate iodine intake, especially for those who consume soy-based foods regularly.
The Best Way to Get Iodine
For those using table salt, make sure it is iodized. Currently, about half of the table salt sold contains iodine, and processed foods typically don’t use iodized salt. Ideally, we should reduce our overall salt intake, as excessive dietary salt is a significant health risk, contributing to millions of deaths annually. Despite this, iodized salt remains an important source of iodine.
The Best Source of Iodine: Sea Vegetables
The most concentrated natural source of iodine is seaweed. Just one gram of seaweed (about the weight of a paperclip) can contain up to 2,000% of the recommended daily iodine intake.
Since iodine is stored in the thyroid, it can be consumed intermittently, meaning you don’t need to eat seaweed every day. This makes seaweed an attractive and occasional source of iodine. However, some seaweed, like kelp, contains very high levels of iodine and should be consumed with caution. Too much iodine can lead to hyperthyroidism, an overactive thyroid. Dr. Greger shares an example of a woman who experienced symptoms like insomnia, anxiety, and weight loss after consuming just two kelp tablets a day.
Iodine Intake Recommendations
The recommended daily iodine intake for non-pregnant, non-breastfeeding adults is 150 mcg/day. It’s advised to stay below 600 mcg/day to avoid excessive iodine intake. For instance, a tablespoon of kelp can contain up to 2,000 mcg of iodine, far exceeding the daily requirement. Therefore, kelp should be avoided due to its high iodine content, as should hijiki, which contains harmful levels of arsenic.
Here’s a guide to common seaweed preparations and their iodine content:
- Two sheets of nori (can be eaten as snacks)
- One teaspoon of dulse flakes (great for sprinkling on dishes)
- One teaspoon of dried arame (perfect for soups)
- One tablespoon of seaweed salad
Dr. Greger notes that the average urinary iodine level of vegans is often below the ideal levels, but some vegans have excessively high iodine levels (over 9,000 mcg/liter). A healthy range for urinary iodine is 100-199 mcg/liter, and levels above 300 mcg/liter are considered excessive.
Iodine and Early Humans
The fact that iodine is concentrated in marine foods raises the question of how early humans, particularly those living in continental areas, met their iodine needs. One possibility is that they may have relied on aquatic plants or freshwater foods. For example, bonobos, our close relatives, forage for aquatic herbs when they visit swamps, which could have provided iodine in their diet.
Summary
In summary, sea vegetables like nori, dulse, and arame are excellent sources of iodine, but it’s important to be cautious with seaweed like kelp due to its high iodine content. Aim to maintain a balanced iodine intake and be mindful of sources like iodized salt or fortified soy milk.
nutritionfacts.org
