Kelp or Kale: Is Seaweed a Superfood?

Kelp Salad

Story at-a-glance -

  • Kelp provides extraordinary amounts of iodine and other minerals, vitamins, antioxidants, phytonutrients, amino acids, omega-3 fats and fiber
  • The nutrients in kelp are commonly linked to your thyroid gland, but are potent enough to protect against cancer and radiation exposure, detox, support normal brain development in babies, and maintain healthy eyes, skin and hair
  • There is compelling evidence that seaweed has ways to protect itself from toxins

By Dr. Mercola

You’ve heard all about all the incredible qualities of kale, but now a shift in the food industry is looking starboard toward the superfood characteristics of kelp.

Kelp: What Is It, Really?

Kelp is one of several seaweed varieties growing in coastal regions around the world, from Japan to Ireland, and the U.S. Coming in black, green, red and brown, some are small; some are so gigantic they form a sort of bed or cushion on the ocean floor and can be seen growing thickly on shorelines.

According to Organic Facts, an online website that provides unbiased information on various food items:

“Giant kelp, which is one of the largest plants in the world, grow enormously and stand like an underwater tree with its roots at the foot of the sea. Unlike a weed that grows liberally and can be harmful to the area it dwells in, seaweed plays an extremely vital role for the marine life.

It serves as a foundation for the majority of the food chains and provides home to a number of marine creatures. In addition to this, seaweed possesses anti-microbial and anti-inflammatory properties that have been trusted for providing health benefits to the humans from ancient times.”1

Also called a sea vegetable, this marine algae is like a leafy green grown in a seabed rather than a garden bed. It’s quite popular in coastal areas of Japan, no doubt because it’s so abundant. Many Japanese claim it’s one of the reasons for their longevity.

Kelp Versus Kale

Comparing kelp to dark, leafy green kale is interesting, as both plants contain quite different nutrient amounts, especially when you examine the Dietary Reference Values (DRV), which give you the daily nutrient recommendations for all foods. For example, kale has more antioxidants than any other vegetable.  

Kale is an excellent source of vitamins A, C, K and B6, calcium, potassium, copper and manganese. More specifically, according to the DRV, it contains 684 percent of vitamin K, 206 percent of vitamin A and 134 percent of vitamin C.

Its sulforaphane content protects against cancer, as does indole-3-carbinol, which also aids in DNA cell repair.

Kelp, aka brown seaweed, contains high amounts of iodine, potassium, magnesium, calcium and iron, as well as vitamins, antioxidants, phytonutrients, amino acids, omega-3 fats and fiber, together relaying impressive health benefits that are hard to ignore.

Kelp Giving Kale a Run for Its Money

Commercial kelp harvesting is arguably its greatest hazard to its sustainability. A century ago, it peaked when around 400,000 wet tons were harvested for fertilizer and for making potash for World War I gunpowder. Then industries began extracting algin from kelp.

“In the 1930s, the food, pharmaceutical and scientific communities began extracting algin, a thickening, stabilizing, suspending, and gelling agent … It … emulsifies salad dressing, and keeps pigments uniformly mixed in paints and cosmetics."2

Kelp, aka “sea greens,” currently sells for around $15 a pound in retail. Ocean Approved, a Maine-based company taking early advantage of the latest resurgence in the marine algae market, is selling kelp to hospitals and schools such as the universities of Iowa and Texas.3

Cultured or farmed dulse, a red variety found off the Irish coast, which grows faster than wild (which costs up to $90 per pound), is thriving, especially in the American market. When it’s fried, one strain grown in Oregon tastes like bacon, and incredibly, contains more protein than kale.

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Kelp: The Largest Source of Iodine

Many foods contain iodine, but nowhere near the tremendous amount in kelp. A single tablespoon provides a whopping 500 percent of the DRV. Nothing else comes close — not scallops, with 90 percent of the DRV, or cod, with 88 percent in servings of 4 ounces each, or a cup of yogurt, which nets 47 percent of the DRV.

According to the George Mateljan Foundation, a non-profit foundation that shares scientifically proven information about the benefits of healthy eating:

“Iodine is a key component of the hormones made in the thyroid gland. These hormones are absolutely critical to human health, helping to control energy production and utilization in nearly every cell of the body."4

Iodine also helps regulate your thyroid gland to produce strong, healthy hair, skin and nails, as well as to form thyroid hormones, thyroxine and triiodothyronine.5 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.6

However, it’s important to understand that balancing your iodine levels is crucial. Specialists usually recommend around 150 micrograms (mcg) daily. Consuming too much could lead to either hypo- or hyperthyroidism.

Kelp’s Versatility and Umami Flavor Makes It a Delicacy

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.7

Kelp isn’t a new commodity in the U.S. People have gathered and consumed it for centuries, including on both American coasts. In fact, scientists have theorized about a "kelp highway" facilitating migration from Japan, along Siberia, to Alaska. 8

A 2010 UN report estimates that Southeast Asia is responsible for more than 99 percent of seaweed production worldwide. However, 100,000 to 170,000 tons of (wet) kelp are harvested from California waters every year.9

Recently, seaweed has been grown fresh, frozen and marketed in the U.S. It doesn’t require fertilizer, fresh water or land like other commercially viable food crops.

Savoring the Valuable Nutritional Benefits of Kelp      

Over a century ago, a Japanese chemist discovered that dulse contains glutamic acid, known in your body as glutamate, central to the nervous system and most aspects of cognition, memory, learning and normal brain function.10

Kelp may induce apoptosis in estrogen-linked breast, endometrial and ovarian cancers11 by decreasing levels of the sex hormone estradiol.

A review12 showed it induced apoptosis in prostate, liver, oral, pancreatic and other cancers, inhibits Helicobacter pylori, which causes stomach ulcers, and targets inflammatory skin conditions.

Further, kelp contains alginic acid, which protects the plants from bacteria, but in your body can reduce radiation exposure and prevent heavy metals from being absorbed.

Alginic acid in the seaweed kombu is known for its positive effects on diabetes,13 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.14 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.”15

How Does Kelp Produce These Amazing Health Benefits?

As mentioned, kelp is an excellent source of magnesium, potassium, calcium, boron, soluble fiber and iron, as well as vitamins A, B12, C and E.

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. According to the George Mateljan Foundation:

“One tablespoon of dried sea vegetable will contain between one-half milligram (mg) and 35 mg of iron, and this iron is also accompanied by a measurable amount vitamin C. Since vitamin C acts to increase the bioavailability of plant iron, this combination in sea vegetables may offer a special benefit.16

The balance of iodine in the thyroid gland is tricky, and both too much and too little iodine can slow down the production of hormones. This is not a situation where more is always better.”17

Kelp Supplements and Products

Especially in areas of the world where kelp isn’t readily available, kelp supplements are taken to help prevent problems such as hypothyroidism or goiter due to an iodine deficiency. 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.”18

Kelp is a nutritious food for your diet, which may be depleted of nutrients such as iodine. There are also nutrient-enriched kelp granules to tenderize and flavor numerous dishes. Other products are growing in popularity: skin care products, soap, sunscreen, toothpaste and more.

If the Water’s Not Clean, What About the Seaweed?

Several factors impact the stability of kelp forests, such as kelp harvesting, El Niño-type storms, fish grazing and pollution. While some scientists believe kelp is sustainable, adverse conditions may pose a serious threat. There is concern that while kelp absorbs minerals from sea water, it may also absorb toxins and concentrated contamination. According to the National Oceanic and Atmospheric Administration (NOAA):

“Kelp may experience reduced growth rates and reproductive success in more toxic waters and sediments. Studies on microscopic stages of kelp suggest that kelp is sensitive to sewage, industrial waste discharges, and other causes of poor water and sediment quality.”19

However, Barton Seaver, Healthy and Sustainable Food program director at Harvard, says kelp isn’t just a sustainable crop — it’s a restorative one, due to quick carbon dioxide uptake, which reduces ocean acidification. According to Organic Facts:

“Seaweed can filter excess nitrogen and phosphorus from the water, too. A (NOAA)-funded project in Washington State's Puget Sound is aiming to prove that farmed seaweed can create a 'protective halo' around stressed sea habitats. We're not at a point where we're just focused on doing no harm. We're really beginning to investigate and discover food-production methods that allow us to restore and heal environments."20

Kelp Protects Itself With Iodine

While kelp has iodine that’s protective for humans, it also protects the kelp itself. Discover magazine reported:

“When the kelp is stressed at low tide by exposure to light and atmospheric ozone, it releases iodides — single, negatively charged ions — that coat the seaweed and protect it from chemical threats, such as naturally forming hydrogen peroxide and free radicals. The iodides also form iodine in the atmosphere.

This response may be the most chemically simple — and first inorganic (not carbon based) — antioxidant ever found. The protection extends beyond the kelp. Previously it was shown that iodine released from kelp provides the nuclei for cloud condensation, or particles upon which clouds can form. Algae may help reduce ozone accumulation and maintain the integrity of the atmosphere.”21

One innovative operation in Long Island Sound takes advantage of this, growing kelp with shellfish, because the kelp protects the shellfish from harmful algae blooms, while the algae simultaneously thrives on nitrogen that deprives the waters of oxygen.22 Additionally, there are four nationally protected marine environments.

“Monitoring projects actively continue in the four sanctuaries. With ongoing surveys of kelp extent (and) physical oceanic conditions … the researchers will gain a more complete understanding of natural and antropogenic impacts on kelp forests.”