Kelp is a delicious superfood with a wide range of benefits for anyone. This select type of seaweed has been a staple of Asian diets for centuries, but now everyone can enjoy its bold taste and fabulous health effects!
Let’s explore in more detail all the health benefits of sea kelp, its side effects, and the types of kelp products and supplements you can try.
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What is Sea Kelp?
Sea kelp, or brown algae, is the generic name for the seaweeds that make the order Laminariales. Kelp grows in huge underwater forests in shallow parts of the ocean, with some forests covering over 2230 square miles!
Kelp thrives in cold and turbulent ocean water with strong currents that bring enough nutrients for the algae to grow. The coasts of Norway, Japan, Mexico, and California are some of the most abundant in terms of natural kelp density.
Sea Kelp Benefits
Sea kelp is rich in various nutrients, minerals, and active compounds. Some have great nutritional value, while others show antioxidative and anti-inflammatory properties, help with diabetes, and may even fight off some types of cancer.
In other words, sea kelp is jam-packed with health benefits. Let’s explore some of them in more detail one by one!
Natural Source of Iodine
In general, all types of seaweed are the best natural sources of iodine. Depending on the specific variety, place of growth, and other factors, a single gram of seaweed contains 16 to 2,984 mcg of iodine. To put that into perspective, the recommended daily allowance (RDA) for iodine in adults is just 150 mcg—or up to 220-290 mcg during pregnancy and lactation.1
Iodine is a crucial microelement for general health, primarily because it’s an essential component of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). These two hormones control a wide range of processes in the body, including energy metabolism, the production of proteins, and the activity of some enzymes. Additionally, these hormones play a vital role in the healthy development of the nervous system and skeleton in fetuses and newborns.1
The importance of iodine is hard to overestimate. So, how can you bring more kelp into your life to meet your daily dose of iodine? The easiest ways are to take kelp supplements or eat different foods with kelp.
- Powdered kelp is the simplest kelp supplement—and probably the most versatile one. For example, powdered kelp can be used as an ingredient in green smoothies, hair, and face masks, or just dissolved in water and drank as is. The only problem with this kelp supplement is its strong fishy smell and taste that some people may find unpleasant.
- Kelp Pills are much more pleasant to take and have just the same benefits as powdered kelp. Perfect for those who dislike powdered kelp supplements’ fishy smell.
- Kelp Extract is another convenient kelp supplement primarily used for a good dose of natural iodine. The downside is that kelp extracts may lack some of the nutrients found in whole kelp supplements in powdered, pill, or tablet form.
Other Sources of Kelp
- Kelp Noodles are a popular dish in Asia, especially in Japan. These semi-transparent noodles are prepared using the jelly-like residue left after steaming kelp. Loved for their extremely low-calorie count, kelp noodles are cholesterol-free, gluten-free, and fat-free—while rich in calcium, iron, and vitamin K at the same time.
- Seaweed Salad is another great way to enjoy sea kelp with various delicious variations. Try it with sesame salad dressing—or sprinkle a pinch of sesame seeds on top!
- Dried Kelp Chips. Dried kelp chips are trendy in Asia and one of the healthiest savory snacks out there. Often seasoned with salt, pepper, and different herbs, they pack a good punch of flavor and a minuscule amount of calories simultaneously.
Kelp Nutrition Facts
According to the USDA Food Database, here’s the nutritional value of 3.5 oz (100 g) of raw sea kelp:2
Macronutrients in sea kelp
- Energy – 43 kcal
- Protein – 1.68 g
- Total fat – 0.56 g
- Carbohydrate – 9.57 g
- Fiber – 1.3 g
- Sugars – 0.6 g
Minerals in sea kelp
- Calcium – 168 mg
- Iron – 2.85 mg
- Magnesium – 121 mg
- Phosphorus – 42 mg
- Potassium – 89 mg
- Sodium – 233 mg
- Zinc – 1.23 mg
- Copper – 0.13 mg
- Manganese – 0.2 mg
- Selenium – 0.7 mcg
Vitamins in sea kelp
- Vitamin C – 3 mg
- Vitamin B1 – 0.05 mg
- Vitamin B2 – 0.15 mg
- Vitamin B3 – 0.47 mg
- Vitamin B5 – 0.642 mg
- Vitamin B6 – 0.002 mg
- Vitamin B9 – 180 mcg
- Vitamin A – 6 mcg (116 IU)
- Vitamin E – 0.87 mg
- Vitamin K – 66 mcg
Health Benefits of Kelp
Now that you know more about the outstanding nutritional value of kelp and some delicious ideas on how to enjoy it, let’s dig into the potential health benefits you can expect from this fabulous food!
Benefits to Thyroid Health
Thanks to its high iodine content, kelp is fabulous for thyroid health. Kelp is particularly great against hypothyroidism (lack of thyroid hormones) due to iodine deficiency.
One small study confirmed this by giving 1 to 2 grams of kelp powder daily to 7 patients with severe hypothyroidism. This dose of kelp contained about 200-400 mcg of iodine and was enough to restore thyroid function fully!3
Remember, though, that it’s possible to overdose on iodine—even if you get it from a natural source like sea kelp. More information on this is in the Potential Side Effects section of this article.
Sugar Regulation Management
Blood sugar dysregulation is characterized by a constant increase in blood sugar (glucose) levels. This high blood sugar damages the blood vessels and nerves, leading to many complications.
The good news is that taking sea kelp could help manage this condition and maybe even prevent complications. One study reported that taking 48 g of seaweed (in pill form) daily for four weeks resulted in significantly lower fasting and after-meal blood glucose levels in patients with type 2 diabetes. The same study reported that sea kelp pills could reduce blood lipids and increase the activity of antioxidative enzymes, which is fabulous for heart health.4
Weight Loss Benefits
Thyroid health is essential for weight management, and that’s why thyroid deficiency is often accompanied by weight gain due to slowed metabolism and the accumulation of water and salt in the body. According to the American Thyroid Association, about 5-10 pounds of body weight could be caused by low thyroid activity, depending on the severity of the condition.5 Being a rich source of iodine, sea kelp help to keep the thyroid gland healthy and prevent thyroid deficiency.
Also, scientists reported that some of the active compounds in seaweed have anti-obesity properties. For example, one study revealed that a combination of fucoxanthin (a pigment from sea kelp) and pomegranate seed oil was able to promote weight loss, decrease body fat content, and improve liver function in 151 non-diabetic obese women.6
In animal studies, Fucoxanthin showed similar anti-obesity effects, too, so the preliminary results are encouraging!7
Abnormal Cellular Growth
Although sea kelp isn’t powerful enough to combat such a complex health condition as cancer, its active compounds could provide some natural support. Sea kelp is rich in natural antioxidants that scavenge and neutralize free radicals—one of the many risk factors for developing cancer.
For example, studies reported that an active compound in brown algae called fucoidan shows anti-tumor potential against colon, breast, lung, and liver cancer.8 More studies are needed before we know all the details, but the results are encouraging so far.
All types of kelp contain numerous compounds that show natural anti-inflammatory action. Since inflammation is a universal process that accompanies virtually all diseases, this useful property of kelp could be useful for anyone searching for a safe way to support their health.
For example, some brown algae contain fucosterol and various phlorotannins that soothe inflammation by suppressing the production of nitric oxide and reactive oxygen species.9 Fucoidan, another active compound in kelp, reduces inflammation by dialing down oxidative stress.10
According to laboratory and animal studies, the fucoidan present in sea kelp is a powerful natural antioxidant.11
Antioxidants like fucoidan scavenge and neutralize the free radicals formed in the body due to enzymatic processes or external factors like ultraviolet radiation. Although forming free radicals is a natural and generally unavoidable process, high levels of free radicals lead to increased oxidative stress. In the end, this increased oxidative stress contributes to the development of many diseases, including cancer.  It’s great to know that such delicious foods like sea kelp could help to mitigate the risk!
Potential Kelp Side Effects
Sea kelp is generally safe, and side effects related to its consumption are rare. However, just in case, there are still a few things to remember.
- Iodine Overdose. Although iodine is essential for strong health, you can have too much of a good thing. Consuming too much iodine with your food or supplements disrupts thyroid function. Depending on various factors, it may lead to either hyperthyroidism (excess thyroid activity) or hypothyroidism (thyroid deficiency).13 Do not exceed the RDA of iodine for adults, which is 150 mcg for the general adult population, 220 mcg during pregnancy, and 290 mcg during lactation.1
- Heavy Metal Poisoning. One study tested nine random kelp products from local food stores for arsenic content, and 8 of the tested products had arsenic levels above the allowed by the FDA.14 Some other studies highlight that seaweed is often rich in cadmium, another heavy metal.15 It’s important to purchase your kelp product or kelp supplement only from a trusted source, preferably with laboratory certificates regarding heavy metal content in their items.
- Contaminated Supplements. If you choose kelp supplements over kelp as food, remember that many natural supplement manufacturers have sub-standard safety measures in place. As a result, some supplements are contaminated with heavy metals, allergens, and other harmful substances. Again, purchase supplements only from a trusted source to avoid taking contaminated and dangerous products.
Sea kelp is a delicious food with fabulous nutritional value and a wide range of potential health benefits. Whether looking for a natural way to support your thyroid health, a supplement to aid in weight loss, or something to fight inflammation gently, seaweed is a great choice.
The easiest way to reap all the sea kelp benefits is to eat it as a food, for example, kelp noodles, dried kelp chips, or seaweed salad. Most Asian cuisines are rich in creative kelp recipes, so explore them to find what works best for you!
Alternatively, you can take sea kelp supplements like powdered kelp, kelp pills, or kelp extracts. These are more convenient but have downsides like a higher price and the risk of buying a low-quality product contaminated with heavy metals or other dangerous substances. That’s why purchasing your kelp supplements only from a trusted manufacturer is so important.
In any case, keep in mind that the iodine content of kelp makes it great—and potentially dangerous at the same time if you don’t control your intake. Check the nutritional value of your kelp product supplement to see the iodine content of your item. Never take more than 150 mcg of iodine daily, which is the RDA of iodine for adults!1
- “Iodine – Fact Sheet for Health Professionals.” National Institutes of Health, Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/
- “Seaweed, kelp, raw.” U.S. Department of Agriculture – FoodData Central Search Results. https://fdc.nal.usda.gov/fdc-app.html#/food-details/168457/nutrients
- Takeuchi, Takako et al. “Treatment of Hypothyroidism due to Iodine Deficiency Using Daily Powdered Kelp in Patients Receiving Long-term Total Enteral Nutrition.” Clinical pediatric endocrinology: case reports and clinical investigations: official Journal of the Japanese Society for Pediatric Endocrinology vol. 20,3 (2011): 51-5.
- Kim, Min Sun et al. “Effects of seaweed supplementation on blood glucose concentration, lipid profile, and antioxidant enzyme activities in patients with type 2 diabetes mellitus.” Nutrition research and practice, vol. 2,2 (2008): 62-7.
- “Thyroid and Weight.” American Thyroid Association. https://www.thyroid.org/thyroid-and-weight/
- Abidov, M et al. “The effects of Xanthigen in the weight management of obese premenopausal women with non-alcoholic fatty liver disease and normal liver fat.” Diabetes, obesity & metabolism vol. 12,1 (2010): 72-81.
- Maeda, Hayato et al. “Fucoxanthin from edible seaweed, Undaria pinnatifida, shows anti-obesity effect through UCP1 expression in white adipose tissues.” Biochemical and biophysical research communications vol. 332,2 (2005): 392-7.
- Kwak, Jong-Young. “Fucoidan as a marine anticancer agent in preclinical development.” Marine drugs, vol. 12,2 (2014): 851-70.
- Jung, Hyun Ah et al. “Anti-inflammatory activity of edible brown alga Eisenia bicyclis and its constituents fucosterol and phlorotannins in LPS-stimulated RAW264.7 macrophages.” Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association vol. 59 (2013): 199-206.
- Yokota, Takashi et al. “Fucoidan alleviates high-fat diet-induced dyslipidemia and atherosclerosis in ApoE(shl) mice deficient in apolipoprotein E expression.” The Journal of nutritional biochemistry vol. 32 (2016): 46-54.
- Li, Bo et al. “Fucoidan: structure and bioactivity.” Molecules (Basel, Switzerland) vol. 13,8 (2008): 1671-95.
- Sainz, Rosa M et al. “Radical decisions in cancer: redox control of cell growth and death.” Cancers vol. 4,2 (2012): 442-74.
- Katagiri, Ryoko et al. “Effect of excess iodine intake on thyroid diseases in different populations: A systematic review and meta-analyses including observational studies.” PLOS ONE vol. 12,3 (2017): e0173722.
- Amster, Eric et al. “Case report: potential arsenic toxicosis secondary to herbal kelp supplement.” Environmental health perspectives vol. 115,4 (2007): 606-8.
- Tchounwou, Paul B et al. “Heavy metal toxicity and the environment.” Experientia supplementum (2012) vol. 101, (2012): 133-64.