The problems of vegans and vegetarians

Iodine is a mineral element the daily need of which is only several micrograms, but its deficiency is nonetheless a worldwide problem. There are not so many good sources of iodine, and its production depends primarily on how high is the iodine content in the soil where the food was grown. Finnish soil has low iodine content which is why iodine is added to edible salt and animal feed. For this reason, this problem relates mainly to vegans. The followers of a balanced diet get their iodine, in addition to salt, also from seafood and products derived from animals that were fed iodized feed. But the sea offers another good source of iodine for vegans — seaweed. The iodine content in seaweed varies greatly and depends not only on the species, but also on the place of its growth (1). Kelp and kombu algae contain more iodine, while spirulina and nori that are used in sushi contain less (see the table).

Iodine deficiency dulls

Iodine is extremely important for the functioning of the thyroid gland since thyroid hormones use iodine as a building material. Thyroid hormones are necessary for brain development during fetal development as well as during the first years of life (2). Iodine is absorbed from food almost completely and is stored in the thyroid gland. If iodine deficiency continues over a long period of time, the body depletes its reserves which results in thyroid insufficiency (hypothyroidism), which in the worst case can lead to enlargement of the thyroid gland and to the occurrence of goiter. The presence of goiter in Finland was common before iodine was added to salt and animal feed. Cretinism and the associated impairment of mental development are the worst consequences of iodine deficiency during the prenatal period (2). Fortunately, cretinism is rare and has almost completely disappeared in Europe (3), but a slight iodine deficiency is common, and a particular concern cause the studies on iodine deficiency among pregnant women (4–6). Even a slight lack of iodine during pregnancy causes impairment of mental abilities of a newborn and, thus, affects the child’s school performance, for example. It is amazing how little attention — among the vegan community too — is given to this mineral element the lack of which can cause such serious consequences. For example, foods with calcium are available to every taste, but there are only two varieties of vegetable milk with iodine (Yosa and Valio’s oat milk). Fortunately, the increased use of iodized salt in the food industry is improving this drawback.

Problem salt with iodine

For many decades, the World Health Organization has been struggling with the problem of iodine deficiency, and iodine is still often considered a problem in the developing countries. However, this issue also applies to the residents of developed countries. Although some progress has been made, almost two billion people around the world are at risk of iodine deficiency (4), and 20% of this number are Europeans (3). Surprisingly, according to the 2007 WHO report, insufficient intake of iodine was more common among European students (60%) than among African students (42%) (3). The lack of iodine even returned to those countries of Europe where, as previously believed, it was eradicated. Finland is one such country in which the iodine situation has worsened (7). This was also discovered by the State Food Commission in 2015, when it began to require bakeries and other food industry players to use iodized salt in the production.

Salt iodization is the most common way to combat iodine deficiency. More than 120 countries iodize edible salt (8). However, there are some problems with salt iodization. For example, dishes intended for small children are not salted because salt is an extra load for children’s kidneys and it complicates metabolism. For medical reasons, adults are also advised to limit their salt intake as it is known that salt, for example, increases blood pressure. Daily salt consumption should not exceed 5 grams per day. When using salt in accordance with the recommendations, the WHO estimates (8) that the iodine content will be 39 mg per 1 kilogram of salt. This indicator in Finland is now 25 mg per kilogram of salt. The current decrease in iodized salt intake is but another problem. This is due to the latest eating-out trend and the growing popularity of special types of salt that do not contain iodine. For example, sea salt contains negligible amounts of iodine (9).

A few years ago, any salt, with the exception of that used in home cooking, was rarely iodized. However, the food industry in Finland began to carefully follow the recommendations of the State Food Commission, and iodized salt is now used in bakery and other food products. In Western countries, the source of about 80% of salt is food products (7). In addition to Finland, the method of using iodized salt in bread which has shown positive results is used in Belgium and Denmark.

In order to combat iodine deficiency, there have been made attempts to use iodized vegetable oil, water, and even tea and sugar with increased iodine content (8).

How can the iodine intake by vegans be improved?

The recommended daily dose of iodine is 150 mcg for adults. The recommended dose of iodine for pregnant women in Finland (175 mcg a day) is significantly less than the WHO dose (250 mcg a day). Pregnant women are recommended to consume iodine supplements (150 mcg) in addition to iodized salt (4). Supplements must be used already at the stage of pregnancy planning, since the most critical period is precisely the initial stage of pregnancy. The dose of iodine for a child ranges from 70 mcg for very small kids to 120 mcg for school children. Starting at the age of 10, the recommended dose is the same as for adults.

The situation with iodine deficiency among vegans leaves much to be desired both in Europe and in America. The intake of iodine from food is half as much as recommended (10, 11). An indicator of iodine in your body is the iodine excreted in the urine. Due to a slight iodine deficiency (12, 13), these indicators in vegans were often quite serious (14). Despite this, fortunately, the risk of thyroid insufficiency in vegans is much lower than in individuals on a balanced diet or in lacto-ovarian vegetarians (15). However, a single case has been described in the literature that emphasizes the importance of iodine supplements during pregnancy. One pregnant vegan had developed a goiter during pregnancy (16), and iodine deficiency was also detected in her baby. Fortunately, both were cured by appropriate treatment. The mother did not eat iodized salt.

To makes things worse, plants contain a large number of various compounds that interfere with the performance of the thyroid gland, preventing the inflow of iodine into the thyroid gland (2). They are called goitrogens. Goitrogens are present, in particular, in tobacco smoke, humus-containing water, cabbage, arugula salad, some legumes and sweet potato. The action of goitrogens is significant only when a person has iodine deficiency (2). In this regard, soy is a concern for many vegans, since soy is actually one of goitrogens. Studies show that even large volumes of soybean do not interfere with the thyroid gland (17). However, soy may in some way impede the absorption of the synthetic thyroid hormone — but many other foods do the same. In addition, perchlorate, a fairly common and often found in nature ecological poison, also prevents the entry of iodine into the thyroid gland (12).

Everything can be excessive, even iodine, although the body can withstand quite large amounts of it. Continuous daily intake of iodine in the amount of 600 micrograms is already dangerous, especially for fetal growth. For this reason, pregnant women are not recommended to eat seaweed. It is important to know the iodine content of the algae that you consume as food. For example, a quarter of a teaspoon of dry Bioteek seaweed supplement contains 670 micrograms of iodine. Jodix iodine tablets taken in case of radiation hazard are not suitable as a dietary supplement. One tablet contains 30,600 micrograms of iodine, which is 51 times higher than the safe daily intake.

Iodine intake instructions for vegans

I have not seen any detailed instructions for vegans in Finland regarding the iodine. Vegans are usually only encouraged to pay attention to the iodine intake. For this reason, I made the following recommendations for vegans:

• Do not increase salt intake to increase iodine intake (for example, sprinkle food with salt), but simply replace your regular salt with iodized salt
• Take a drug containing 150–200 micrograms of iodine 3–4 days a week OR eat seaweed, at least with the same frequency, the iodine content of which you know. For example, Vitatabs jodi that is sold in pharmacies contains 150 micrograms of iodine, or Veg1 special multivitamins for vegans. Kelp seaweed tablets contain 200 micrograms of iodine.
• When planning pregnancy, do not eat daily supplements with an iodine content exceeding 150 mcg, nor during pregnancy or breastfeeding. Women during pregnancy and breastfeeding, as well as small children, should eat other sources of iodine apart from seaweed, since some seaweed may contain a dangerous amount of heavy metals (18, 19).

Iodine content in seaweed
(sources 1, 20–21, as well as research results from the laboratories of the Customs Administration and the Food Safety Agency (Evira))

Source: vegaaniravitsemus.fi/jodi (site about vegan nutrition)
Do you get enough iodine?
03/01/2016 (updated 10/24/2018)

Literature

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