Brown algae, red algae, green algae, blue-green algae – many algae in dazzling colors grow around the globe in Neptune’s garden. And although this vegetable patch lies below sea level, humans are also reaping the colorful harvest here. Anyone who likes sushi or other Asian dishes has certainly held a seaweed leaf on a spoon or, more authentically, between chopsticks.
Algae as a dietary supplement?
The ingredients of some algae, so-called microalgae, are also offered in tablets or powders as dietary supplements. However, the colorful “sea foliage” should be used with caution: Due to their exceptionally high iodine content, some algae that end up on your plate have a negative effect on the thyroid gland. Also, the question of what to look for when supplementing your diet with tablets or powders made from algae will be answered here in the rest of this article.
Algae – what kind of plants are they?
Among the algae mentioned, two groups are distinguished: The so-called macroalgae are what one classically imagines under sea algae, i.e. regular underwater plants. These include brown, red and green algae, which are found in many Asian dishes. Blue-green algae, on the other hand, are not actually algae at all, but a special type of bacteria. These cyanobacteria have the special feature that they – like plants – can obtain energy with the help of chlorophyll. The chlorophyll gives them their green-blue color. Virtually everyone has seen blue-green algae, as they like to form in still waters that are exposed to light. Aquarium owners know a thing or two about the invaders that tend to attach themselves to glass walls, clouding the view of their native underwater world in a greenish hue.
Blue-green algae can be harmful to health
The cyanobacteria can form toxins, which in high concentrations can have a dangerous effect on health. If the blue-green algae form algal blooms en masse, a health risk can occur in swimming lakes, for example. When coming into contact with blue-green algae or after swallowing water contaminated with the toxins, the following symptoms may occur:
- Skin and mucous membrane irritation
- Conjunctivitis
- Earache
- Diarrhea
- Fever
- Respiratory diseases
- Allergic reactions
Especially for young children, swallowing large amounts is dangerous.
When Europeans eat like Asians.
For the Japanese, large quantities of seaweed traditionally end up in the kitchen pot, as the lack of large agricultural areas and the direct availability of seaweed on the long coastlines of the Japanese islands have invited the use of the sea vegetable for centuries. As healthy as the high-fiber, low-fat Asian cuisine is, the iodine content of some of its seaweeds far exceeds anything the ingredients of European cuisine have to offer. The brown algae Kombu, for example, has it all: it can store astonishing amounts of iodine. The iodine concentration in kombu leaves is 40,000 times higher than in normal seawater, and just one-twentieth of a gram of the dried leaves is enough to meet a person’s daily iodine intake.
Excessive iodine intake as a danger to the thyroid gland
A sudden, excessive intake of the mineral can have undesirable consequences: So-called “functional autonomies” can be activated in the thyroid gland. These are nodules (autonomous adenomas) that form especially with prolonged insufficient iodine intake. If these areas of the thyroid gland that are “thirsty” for iodine are suddenly supplied with an excess of iodine, they begin to produce thyroid hormones out of control: Acute hyperthyroidism can result.
Japanese are (almost) resistant
Because the Japanese and other Asians take in a lot of iodine throughout their lives through their high consumption of algae, virtually no autonomic nodules are found in thyroid examinations of the population, and therefore there are no problems with algae consumption. However, even for the iodine-tested Asians, it can sometimes be too much of a good thing: In some areas of the Japanese coast, an astonishing number of people are found with goiter, as is also increasingly the case in the iodine-deficient Alpine countries.Goiter, an enlargement of the thyroid gland, is actually a symptom of iodine deficiency, but it can also be triggered by a very extremely high iodine intake. In this case, the system responsible for the uptake of iodine into the thyroid gland is so irritated by the iodine glut that it unceremoniously stops the uptake. This leads to an iodine deficiency in the thyroid gland despite the excess of iodine in the blood. This effect, also known as Wolf f-Chaikoff block, can likewise affect the unborn child of a pregnant woman, which is why she should also be careful (in addition to having an adequate) intake of the element that is not too high.
Eating algae: Here’s what to look out for
First of all, it should be noted that only part of the Asian algae is so extremely rich in iodine. Primarily, these are the brown algae kombu and wakame. Kombu is usually boiled in water, and the resulting broth is the basis of most Japanese soups. The firm green leaves of wakame are used as a garnish in soups as well as for salads. Nori, on the other hand, is used as a “wrapper” for maki sushi. However, those who do not consume too wild amounts of the sushi need not worry here, as nori does not appear to have extreme iodine levels. The iodine content of the seaweed not only varies from variety to variety, but can also vary greatly depending on the time of harvest and where it is grown. In addition, seaweed loses up to 87 percent of its iodine content during preparation. However, since the recommended amount of iodine in the dry weight of algae is still 20 to 195 times the limit in some cases, the problem should still not be downplayed.
Beware of too much iodine
According to the German Federal Institute for Risk Assessment (BfR), the iodine content in dried algae varies extremely, ranging from five to 11,000 micrograms per gram. However, the BfR recommends only 0.5 milligrams per day as the maximum amount. In a statement from 2007, the BfR draws attention to the fact that with high iodine contents, consumption of as little as ten grams of algae leads to an excessive intake of iodine. However, information on the amount of algae contained or the iodine content is often missing on products.
Microalgae: Panacea and food source of the future?
When microalgae are mentioned, they primarily refer to the species Aphanizomenon flos-aquae (also called “AFA algae”), chlorella and spirulina. What they have in common is that many myths surround the single-celled organisms often referred to as “primordial algae”. Due to their protein richness and the fact that they do not require arable land for cultivation and, like plants, produce their own requirements of biological building blocks through photosynthesis, they are considered by many to be the solution to the nutritional problem of a constantly growing world population. Although this idea is not entirely new, previous efforts have not been successful in large-scale cultivation of algae. The aforementioned microalgae, most notably the AFA algae, also serve as the basis of countless tablets and powders sold as nutritional supplements. The “primordial algae” are often claimed, more or less explicitly, to be effective against numerous diseases, including cancer and AIDS. However, such claims have not been proven to date.
Are algae products pharmaceuticals?
Any product that is claimed to cure, alleviate or prevent disease is legally considered a drug. However, these need government approval, which requires proof that the product actually produces the desired effect and has no harmful effects. Since no algae product is currently approved as a drug in the Federal Republic of Germany, none of these products may be claimed to have a medicinal effect. It is therefore advisable in any case to consult a doctor instead of trying to cure yourself or others with an algae product.
Toxic substances in algae
The issue is given additional poignancy by the fact that many AFA products contain the toxic substance microcystin. Microcystins are found in many cyanobacterial species and are often included in finished products made from blue-green algae that are available on the market as dietary supplements. Microcystin has a liver-damaging effect and is considered a tumor promoter – so the substance itself is not carcinogenic, but it increases the likelihood of carcinogens. In an American study, all of the AFA products examined contained these microcystins, and in some cases the maximum tolerable concentrations according to the WHO were exceeded.For this reason, it is not recommended to give AFA algae products to children, and a reduction in the dose is recommended for adults when taking them.
