Kelps are seaweeds that grow in particular shallow and nutrient-rich waters around the world. They’ve been eaten and used medicinally for hundreds of years in various forms, and are processed today, with some by-products commonly used in ice cream, salad dressings and even chocolate milk.
According to nutritionist Vanessa Stasio Costa, M.S., R.D.N., C.D.N., kelp “is often considered a ‘superfood’ due to its significant mineral content. It’s especially concentrated in iodine, which is important for optimal thyroid function and metabolism.”
The National Institutes of Health (NIH) say that seaweed such as kelp is one of the best natural food sources of iodine, an essential component in thyroid hormone production. A deficiency in iodine leads to metabolism disruption and can also lead to an enlargement of the thyroid gland known as goiter.
TYPES OF SEAWEED
Scientists have categorized types of seaweed into different categories based on their pigments, cell structure, and other traits. The groups (or phyta) of seaweed that are commonly consumed include:
- Green algae such as sea lettuce or ulva, and sea grapes
- Brown algae such as kombu, arame, kelp, and wakame (the miso soup seaweed)
- Red algae such as dulse, laver, and nori (the sushi seaweed)
- Blue-green algae such as spirulina and chlorella
BENEFITS OF SEA KELP & SEAWEED
Anti-ageing: The iodine content of kelp also appears to have other benefits. A 2008 study showed that the form of iodine in kelp effectively removed free radicals – chemicals that accelerate ageing – from human blood cells.
Anti-cancer: Researchers found that kelp can slow the spread of colon and breast cancers. A compound found in kelp called fucoidan may also prevent the spread of lung cancer and prostate cancer. The presence of fucoxanthin was found to be effective against a number of types of prostate cancer. In addition, fucoxanthin can help remove drug resistance in cancer patients undergoing dangerous chemotherapy treatments, thereby reducing the amount of harmful drugs introduced into one’s system in order to treat cancer.
Anti-inflammatory: Kelp is naturally high in antioxidants, including carotenoids, flavonoids, and alkaloids, which help to fight against disease-causing free radicals. Antioxidant vitamins like vitamin C, and minerals like manganese and zinc, help to combat oxidative stress and may offer benefits to cardiovascular health. Fucoidan, found in kelp, has also been shown to work as an anti-inflammatory and also to improve cholesterol levels in the blood, responsible for heart conditions.
Anti-radiation: Livestrong noted: “Sodium alginate derived from kelp reduced radioactive strontium absorption in the intestines by 50 to 80 percent … (allowing) calcium to be absorbed through the intestinal wall while binding most of the strontium, which is excreted from the body.”
Blood thinner: Fucoidan has shown effectiveness in preventing blood clots that can lead to dangerous health problems, including stroke and heart attack. It’s so effective, in fact, that researchers cite it as having potential to be used as an oral antithrombotic agent, potentially reducing the need of prescription drugs to treat clotting problems.
Bone Loss: a rich source of vitamin K — you get almost a quarter of the daily recommended intake of vitamin K in just one serving. One of the many benefits of vitamin K is its role in creating denser bones that don’t as easily succumb to arthritis and osteoporosis. However, people on blood-thinning drugs ought to avoid extra vitamin K, as it can affect how the drugs work. Fucoidan also contributes to healthy bones. Low molecular weight fucoidan helps prevent age-related bone loss and improves the mineral density in bones.
Brain health: seaweed provides glutamic acid, known in your body as glutamate, central to the nervous system and most aspects of cognition, memory, learning and normal brain function.
Hair growth: There’s plenty of anecdotal evidence suggesting taking sea kelp supplements can boost hair growth. Whether or not it actually boosts growth, it contains nutrients involved in hair health and strength, so it may help reduce split ends and breakages.
Iodine: helps regulate your thyroid gland to produce strong, healthy hair, skin and nails, as well as to form thyroid hormones, thyroxine and triiodothyronine. It’s also essential for proper formation of your skeletal framework and regulating your body’s energy and brain metabolism in a process regulated by your pituitary gland. The myelination process in the central nervous systems of newborns is another key function of the thyroid hormone. Balanced iodine in the mother’s body is imperative in pregnancy and breastfeeding for optimal development of the baby’s brain cells. Specialists usually recommend around 150 micrograms (mcg) daily. Consuming too much could lead to either hypo- or hyperthyroidism.
Nutrients: Sea kelp is a natural source of vitamins A, B1, B2, C, D and E, as well as minerals including zinc, iodine, magnesium, iron, potassium, copper and calcium. In fact it contains the highest natural concentration of calcium of any food – 10 times more than milk.
Below is the average iodine content of three different dried seaweeds:
- Nori: 37 mcg per gram (25% of the RDI)
- Wakame: 139 mcg per gram (93% of the RDI)
- Kombu: 2523 mcg per gram (1,682% of the RDI)
Generally, 1 tablespoon (7 grams) of dried spirulina can provide:
- Calories: 20
- Carbs: 1.7 grams
- Protein: 4 grams
- Fat: 0.5 gram
- Fiber: 0.3 grams
- Riboflavin: 15% of the RDI
- Thiamin: 11% of the RDI
- Iron: 11% of the RDI
- Manganese: 7% of the RDI
- Copper: 21% of the RDI
One serving of raw kelp (about 28 grams) contains about:
- 12 calories
- 7 grams carbohydrates
- 5 gram protein
- 2 gram fat
- 4 gram fiber
- 5 micrograms vitamin K (23 percent DV)
- 4 micrograms folate (13 percent DV)
- 9 milligrams magnesium (8 percent DV)
- 47 milligrams calcium (5 percent DV)
- 8 milligram iron (4 percent DV)
- milligram manganese (3 percent DV)
Seaweed also contains small amounts of vitamins A, C, E and K, along with folate, zinc, sodium, calcium and magnesium.
If you have a family history of diabetes, you should know that kelp is rich in a little-known mineral called vanadium, which is being studied as an important regulator of insulin and blood sugar.
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.
Alginic acid in the seaweed kombu is known for its positive effects on diabetes, as well as its ability to coagulate blood. It prevents dental cavities, promotes digestive health, protects against flu, aids digestion, protects vision and maintains heart health.
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.
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.
The iron in kelp helps form healthy blood and prevent anemia and the antioxidants fight free radicals, altogether ensuring the growth of strong bones and optimal muscle function.
Weight loss: Iodine is a trace mineral vital for the operation of the thyroid gland which plays an important part in body development and metabolism. It combines with tyrosine – an amino acid – to create T3 and T4, thyroid hormones that regulate metabolism and other physiological functions throughout the body. As sea kelp is the richest natural source of iodine it can help to regulate metabolism and in turn affect weight loss and gain.
In recent years, researchers have looked into kelp’s potential fat blocking properties. Because kelp contains a natural fiber called alginate, studies suggest that it may halt the absorption of fat in the gut. A study published in Food Chemistry found that alginate could help block fat absorption in the intestines by 75 percent. In order to reap the benefits of alginate, the research team plans to add the thickening compound to common foods such as yogurt and bread.
Kelp may have great potential for diabetes and obesity, although research is still preliminary. A study published in the journal Diabetes, Obesity and Metabolism found that a compound in the chloroplasts of brown seaweed called fucoxanthin may promote weight loss in obese patients when combined with pomegranate oil. Studies also suggest that brown seaweed may influence glycemic control and reduce blood glucose levels, benefitting people with type 2 diabetes.
RISKS ASSOCIATED WITH SEA KELP
Heavy Metals: Sea kelp grown in polluted waters may well absorb toxic heavy metals which if ingested can cause major health problems. The potential for this means it isn’t recommended to be taken if pregnant or breastfeeding, or by children or people with health issues, especially liver or kidney problems. It should be possible however to make sure a particular supplement comes from kelp grown in clean waters.
Iodine: the iodine within sea kelp is easily absorbed by the body so it can quickly become too much for the body to process. Most people get enough iodine from table salt alone, adding kelp to the diet can greatly increase iodine levels. Too much iodine in the system can cause hyperthyroidism, Grave’s disease, and thyroid cancer. The amount of iodine in each type of kelp food product and supplement vary greatly.
According to the Daily Mail: “Deficiencies can be treated with 150 mcg of iodine daily. Prolonged use of large amounts of iodine (6 mg or more daily) may suppress activity of the thyroid gland. A safe upper limit of iodine is 1,000 mcg per day.”
Unpredictability: There are a large number of sea kelp supplements available containing a variety of different types of algae that all come under the name ‘kelp’, which may affect your body in different ways. For instance, bladderwrack can cause or worsen acne, and there is a single reported case of it causing kidney failure. The effects depend completely on your individual health status and your body’s overall make-up.
HOW TO EAT KELP & SEAWEED
Nutritionist Lisa Moskovitz, R.D., C.D.N., C.P.T., recommends that you try to eat your nutrients, versus taking them in supplement form. She suggests including kelp in a balanced diet with plenty of vegetables, from both the land and sea. Kelp can be one small part of a broader healthy diet that includes a variety of unprocessed, nutrient-dense foods.
Moskovitz says that one of the easiest ways to incorporate kelp into your diet is to add an organic, dried variety into soups. You could also use raw kelp noodles in salads and main dishes or add some dried kelp flakes as seasoning. It is usually found in Japanese or Korean restaurants or grocery stores and can be enjoyed cold with oil and sesame seeds, hot in a soup or stew, or even blended into a vegetable juice.
You can find kelp at most health-food markets or the Asian section of your regular grocery store. If you don’t eat gluten or are cutting back on carbs, try kelp noodles instead of your regular pasta. They’re raw and work great as a substitute in any regular noodle dish. If you can only find dried kelp, reconstitute it with a little water (this doesn’t take long), then drain it and mix it with thinly sliced cucumbers, a splash of sesame oil and Asian vinegar.
As a food, kelp aficionados laud its flavor as the ultimate, seawater-laced brine that’s the essence of umami. Nori, one of the most popular seaweed species, is dried in sheets to make sushi rolls. Other varieties include dulse, arame, which is black; deep green wakame; kombu; and spirulina.
HOW TO COOK & EAT SEAWEED
Dried seaweed would need to be soaked in hot water, and rinsed well before use. Some thicker and tougher seaweed like kombu might be better sliced thin or boiled. Seaweeds are very versatile. Here are a few different ways to enjoy them:
- Snacking out of a bag – Nori and dulse can just be eaten out of a bag. You will want to check the labels and watch out for some brands of snacking nori that contain a lot of MSG though.
- Salads – Most types of seaweed can be made into a Japanese-style salad with vinegar, sesame oil, ginger, and garlic.
- Soups – Seaweed tastes delicious in bone broth, which makes it seaweed soup.
- Sprinkled on other foods – Seaweed flakes can be sprinkled on salads, rice, soups, or any other dishes.
Most seaweed is not bitter. Some types are a bit sweet and may even have umami flavors, which means that it may be easier to get some picky eaters to eat seaweed than vegetables.