Seaweed is used in cuisines all over the world, but it is most popular in Asian countries such as Japan, China, and Korea. It’s a type of edible plant that grows in the sea and comes in different colors including red, green, and brown.
Also known as sea vegetables, these plants are used to make salads, soups, stews, sushi rolls, and smoothies. Seaweed is very nutritious and just like other vegetables, it is a rich source of vitamins, minerals, and fiber. We take a closer look at the science-backed seaweed salad benefits and possible side effects.
Seaweed is gaining popularity for a number of reasons, including that it is both versatile and nutritious. There are many different types of seaweed, including:
These types of seaweed have different tastes and their nutritional profiles differ slightly. Wakame is commonly used to make seaweed salad.
Here are the science-backed seaweed benefits and side effects:
Eating seaweed is a great way to get a lot of nutrients without consuming too many calories.
Wakame seaweed salad nutrition facts per 100 grams (1)
Seaweed is generally a potent source of protein, carbohydrates, fibers, and polyunsaturated lipids such as omega-3 (2). It also contains minerals such as selenium, iron, calcium, magnesium, potassium, sodium, phosphorus, manganese and zinc (3).
Vitamins found in sea vegetables include A, B12, E, C, and K (3). Some seaweed types such as sea lettuce (Ulva lactuca) and hypnea contain all 9 essential amino acids (amino acids that must be obtained from the diet as they cannot be synthesized in the body) (4). So, if you’re trying to cut back on animal protein, seaweed is a great alternative.
The thyroid is a butterfly shaped gland that is found in your neck that produces thyroid hormones. These hormones are responsible for the regulation of weight, internal temperature, metabolism, repair of damaged cells and growth (5). Iodine is required to produce thyroid hormone. As iodine cannot be synthesized by the body, it has to be obtained from the diet.
Seaweed is arguably the best dietary source of iodine. The iodine content however varies depending on the type of seaweed. Below are the estimated average iodine content of 3 different types of dried sea vegetables (6):
If you don’t have enough iodine, your body won’t be able to produce enough thyroid hormone. This may result in symptoms such as fatigue, neck swelling and weight fluctuations. In the case of severe iodine deficiency, a person may develop hypothyroidism or goiter. Interestingly, iodine deficiency is considered one of the most important preventable causes of brain damage throughout the world (7).
Antioxidants are molecules that help prevent or slow damage to cells caused by free radicals. When there is an imbalance of free radicals and antioxidants in the body, this is referred to as oxidative stress. Overproduction of free radicals can eventually contribute to chronic diseases such as cancer, atherosclerosis, diabetes, arthritis, stroke, Parkinson’s, and heart diseases (8).
Seaweed contains an abundance of antioxidants including vitamins A, C, E, and riboflavin and phytochemicals such as carotenoids. All these can help protect cells from damage caused by oxidative stress (9).
One seaweed carotenoid that has sparked a great deal of interest and has been thoroughly researched is fucoxanthin. Fucoxanthin is mainly found in the brown algae, wakame, that is often used to prepare seaweed salad. It is believed to be 13.5 times more powerful than vitamin E as a free radical scavenger (10).
In addition, fucoxanthin has been found to protect cell membranes better than vitamin A (11). Unfortunately, this antioxidant is not well absorbed in the body, but consuming it with fat may improve its absorption (12).
Sea vegetables are rich in fiber, so they’re good for those on a weight loss journey or anyone who wants to increase their fiber intake. The fiber isn’t absorbed or used by the body as energy, but it supports beneficial gut bacteria and helps promote regular bowel movements. Fiber also helps slow gastric emptying. This may increase satiety so you don’t get hungry as soon as you would after eating a low-fiber meal (13).
Seaweed may also possess anti-obesity properties. Research has suggested that compounds such as fucoxanthin and fucoidans that are found in seaweed may inhibit lipid absorption and metabolism. Fucoxanthin may inhibit adipocyte differentiation. A different compound called alginates, which comprises 40% of dry weight in brown seaweeds, may increase satiety and reduce calorie intake (14).
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Next on the seaweed salad nutrition benefit list is that it supports gut health. As previously mentioned, sea vegetables are a potent source of fiber. The fiber in seaweed helps feed friendly gut bacteria (15). An imbalance of good and bad gut bacteria may contribute to diseases and uncomfortable symptoms.
In addition, carbohydrates in brown seaweed known as sulfated polysaccharides may increase the growth of friendly gut bacteria. They may also increase the production of short-chain fatty acids by gut bacteria that support and nourish the cells lining the gut (16).
Heart disease is the number one cause of death globally. Fiber-rich foods such as marine algae may help lower blood cholesterol levels (17). Obesity, a diet rich in saturated fats, smoking, drinking alcohol, and physical inactivity all put you at risk of unhealthy cholesterol levels.
Seaweed also contains fiber, peptides, and carotenoids, all of which may lower serum cholesterol and blood pressure. A study by the Japanese Public Health center found the consumption of seaweed to be inversely related to the risk of stroke (18).
Type 2 diabetes is a disease caused by an impairment in the regulation of blood glucose. It is characterized by high blood sugar levels, insufficient insulin production, and insulin resistance. Risk factors include being overweight, unhealthy eating, a sedentary lifestyle, or a family history of type 2 diabetes.
Seaweed is a fiber-rich food and this may help regulate blood glucose levels (13). In a small study, 9 women and 11 men with diabetes were allocated to either a seaweed supplementation group or control group. At the end of the 4-week study, it was concluded that seaweed improves glycemic control, lowers blood lipids, and increases antioxidant enzyme activities (19).
Other studies have also found that incorporating seaweed into the diet may have antidiabetic effects (20) (21). However, more research is required on the effect of seaweed supplementation.
Seaweed may also help lower your risk of certain cancers such as prostate, colon, and breast. Research has indicated that seaweed and seaweed-derived products may have anti-cancer activities via mechanisms such as the inhibition of cancer cell invasion, growth, and metastases and the induction of apoptosis (22). A 2014 review described the mechanisms by which seaweed may have potential as anti-cancer agents in breast and colorectal cancer (23).
Another review looked at the anti-cancer activity of red seaweed. The study found that terpenes, polyphenols, and polysaccharides are the major contributors of anti-cancer activity in red seaweed. Poryphyran also displays anti-cancer activity as it is toxic for cancer cells and induces cell death. Carrageenan inhibits tumor growth by arresting the cell cycles of tumors at specific phases (24).
Most studies to date on the anti-cancer effects of seaweed have been done in test tubes, so it isn’t fully understood whether or how supplementation with seaweed or including it in the diet may affect cancer risk in humans.
Read more: How to Build a Healthy Dinner Plate, According to Experts
Eating small but regular amounts of seaweed is completely safe. However, there are a few dangers that come with eating too much seaweed. There are 2 major brown seaweed side effects:
While iodine is important for thyroid function, too much can be harmful. An overload of iodine intake may precipitate goiter, hypothyroidism, hyperthyroidism, or thyroid autoimmunity (25). However, most healthy people are able to tolerate moderately high intakes quite well.
In Japan, the daily average intake of iodine is approximately 1,000 to 3,000 micrograms (26) This is way over the tolerable limit of iodine, which is 1,100 micrograms (27). Therefore, eating seaweed poses a risk if consumed every day and in high amounts. Ironically, the high iodine intake is sometimes regarded as one of the reasons why the Japanese people are among the healthiest in the world.
If you think you may be consuming too much iodine and experience symptoms such as neck swelling or weight fluctuations, talk to your physician and reduce your consumption of iodine-rich foods. Also, if you have a thyroid condition or are taking any thyroid medication, consult your doctor before adding seaweed to your diet.
Seaweed can rapidly accumulate high concentrations of metals such as cadmium, copper (III), and copper (IV). Even in trace amounts, metals such as lead, mercury, and cadmium can be toxic. Heavy metals are usually stored in fatty tissues and organs and may have adverse effects on the central nervous system (28).
A 2017 study analyzing metal load in seaweeds from Europe and Asia found that the levels of aluminum, lead, and cadmium in 4 grams of seaweed didn’t pose any health risk (29). However, if you regularly consume seaweed in large amounts, there is potential for metals to accumulate in your body.
Making seaweed salad is just as easy as making tomato salad. Common ingredients that are added to the seaweed include rice vinegar, sesame oil, soy sauce, ginger juice, and scallions. However, as it’s a salad, you can get creative with the ingredients in your pantry and see how it turns out.
Below are 2 simple ways you can prepare a seaweed salad:
You can replace the wakame seaweed with a type you prefer or use more than one kind of seaweed.
Ingredients
Directions
Servings: 4
Nutritional info: 62 calories, 5.8g carbs, 1.6g protein, 3.7g fat
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Instead of the conventional Japanese seaweed salad, you can make this spicy kale version. However, if you’re on a diet, take a quarter or half a serving instead of a full serving.
Ingredients
Directions
Servings: 4
Nutritional info: 2,103 calories, 230 g fat, 15 g carbs, 5g protein
Read more: Low-Potassium Foods to Eat and What to Avoid
Seaweed salad can be a healthy addition to your diet as it’s packed with vitamins, minerals, and antioxidants, including iodine, calcium, and vitamins A, C, E, and K. However, it’s best to consume it in moderation and as part of a varied diet.
There are a few considerations you should keep in mind:
Seaweed salad is mainly served as a starter. It also makes a perfect side dish for many meals, including Thanksgiving turkey or chicken. Seaweed is one of the best sources of dietary iodine and contains many minerals, so it has great health benefits. Too much can be dangerous, so make sure you consume small to moderate amounts of seaweed salad.
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