- Contains Iodine and Tyrosine, Which Support Thyroid Function
Your thyroid gland releases hormones to help control growth, energy production, reproduction and the repair of damaged cells in your body.
Your thyroid relies on iodine to make hormones. Without enough iodine, you may start to experience symptoms like weight changes, fatigue or swelling of the neck over time.
The recommended dietary intake (RDI) for iodine is 150 mcg per day.
Seaweed has the unique ability to absorb concentrated amounts of iodine from the ocean.
Its iodine content varies greatly depending on the type, where it was grown and how it was processed. In fact, one dried sheet of seaweed can contain 11–1,989% of the RDI (7).
Kelp is one of the best sources of iodine. Just one teaspoon (3.5 grams) of dried kelp could contain 59 times the RDI.
Seaweed also contains an amino acid called tyrosine, which is used alongside iodine to make two key hormones that help the thyroid gland do its job properly (9Trusted Source).
- Good Source of Vitamins and Minerals
Each type of seaweed has a unique set of nutrients.
Sprinkling some dried seaweed on your food not only adds taste, texture and flavor to your meal, but it’s an easy way to boost your intake of vitamins and minerals.
Seaweed also contains small amounts of vitamins A, C, E and K, along with folate, zinc, sodium, calcium and magnesium.
While it may only contribute to a small percentage of some of the RDIs above, using it as a seasoning once or twice per week can be an easy way to add more nutrients to your diet.
The protein present in some seaweeds, such as spirulina and chlorella, contain all of the essential amino acids. This means seaweed can help ensure you get the full range of amino acids.
Seaweed can also be a good source of omega-3 fats and vitamin B12.
In fact, it appears that dried green and purple seaweed contain substantial amounts of vitamin B12. One study found 2.4 mcg or 100% of the RDI of vitamin B12 in only 4 grams of nori seaweed.
That said, there is an ongoing debate about whether your body can absorb and use the vitamin B12 from seaweed.
- Contains a Variety of Protective Antioxidants
Antioxidants can make unstable substances in your body called free radicals less reactive.
This makes them less likely to damage your cells.
Furthermore, excess free radical production is considered to be an underlying cause of several diseases, such as heart disease and diabetes.
In addition to containing the antioxidant vitamins A, C and E, seaweed boasts a wide variety of beneficial plant compounds, including flavonoids and carotenoids. These have been shown to protect your body’s cells from free radical damage.
A lot of research has focused on one particular carotenoid called fucoxanthin.
It’s the main carotenoid found in brown algae, such as wakame, and it has 13.5 times the antioxidant capacity as vitamin E.
Fucoxanthin has been shown to protect cell membranes better than vitamin A.
While the body does not always absorb fucoxanthin well, absorption may be improved by consuming it along with fat.
Nevertheless, seaweed contains a wide variety of plant compounds that work together to have strong antioxidant effects.
- Provides Fiber and Polysaccharides That Can Support Your Gut Health
Gut bacteria play an enormous role in your health.
It’s estimated that you have more bacteria cells in your body than human cells.
An imbalance in these “good” and “bad” gut bacteria can lead to sickness and disease.
Seaweed is an excellent source of fiber, which is known to promote gut health.
It can make up about 25–75% of seaweed’s dry weight. This is higher than the fiber content of most fruits and vegetables.
Fiber can resist digestion and be used as a food source for bacteria in your large intestine instead.
Additionally, particular sugars found in seaweed called sulfated polysaccharides have been shown to increase the growth of “good” gut bacteria.
These polysaccharides can also increase the production of short-chain fatty acids (SCFA), which provide support and nourishment to the cells lining your gut.
- May Help You Lose Weight by Delaying Hunger and Reducing Weight
Seaweed contains a lot of fiber, which does not contain any calories.
The fiber in seaweed may slow stomach emptying, too. This helps you feel fuller for longer and can delay hunger pangs.
Seaweed is also considered to have anti-obesity effects. In particular, several animal studies suggest that a substance in seaweed called fucoxanthin may help reduce body fat.
One animal study found that rats who consumed fucoxanthin lost weight, whereas rats who consumed the control diet did not.
The results showed that fucoxanthin increased the expression of a protein that metabolizes fat in rats.
Other animal studies found similar results. For example, fucoxanthin has been shown to significantly reduce blood sugar levels in rats, further aiding weight loss.
Although the results in animal studies appear very promising, it’s important that human studies are conducted to verify these findings.
- May Reduce Heart Disease Risk
Heart disease is the leading cause of death worldwide.
Factors that increase your risk include high cholesterol, high blood pressure, smoking and being physically inactive or overweight.
Interestingly, seaweed may help reduce your blood cholesterol levels.
One eight-week study fed rats with high cholesterol a high-fat diet supplemented with 10% freeze-dried seaweed. It found the rats had 40% lower total cholesterol, 36% lower LDL cholesterol and 31% lower triglyceride levels.
Heart disease can also be caused by excessive blood clotting. Seaweed contains carbohydrates called fucans, which may help prevent blood from clotting.
In fact, one animal study found that fucans extracted from seaweed prevented blood clotting as effectively as an anti-clotting drug.
Researchers are also starting to look at peptides in seaweed. Initial studies in animals indicate that these protein-like structures may block part of a pathway that increases blood pressure in your body.
However, large-scale human studies are required to confirm these results.
- May Help Reduce Your Risk of Type 2 Diabetes by Improving Blood Sugar Control
Diabetes is a major health problem.
It occurs when your body is unable to balance your blood sugar levels over time.
By the year 2040, 642 million people worldwide are expected to have type 1 or type 2 diabetes.
Interestingly, seaweed has become a research focus for new ways to support people who are at risk of diabetes.
An eight-week study in 60 Japanese people revealed that fucoxanthin, a substance in brown seaweed, may help improve blood sugar control.
Participants received a local seaweed oil that contained either 0 mg, 1 mg or 2 mg of fucoxanthin. The study found that those who received 2 mg of fucoxanthin had improved blood sugar levels, compared to the group who received 0 mg.
The study also noted additional improvements in blood sugar levels in those with a genetic disposition to insulin resistance, which usually accompanies type 2 diabetes.
What’s more, another substance in seaweed called alginate prevented blood sugar spikes in animals after they were fed a high-sugar meal. It’s thought that alginate may reduce the absorption of sugar into the bloodstream.
Several other animal studies have reported improved blood sugar control when seaweed extracts are added to the diet.