Sea vegetables

What's New and Beneficial about Sea Vegetables

WHFoods Recommendations

While the broad range of minerals provided by sea vegetables make them a great addition to your Healthiest Way of Eating, Westerners are often not quite sure how to add more of these nutrient-rich foods to their meals. One easy way is to keep a container of kelp flakes on the dinner table and use it instead of table salt for seasoning foods. You can also experiment with adding your favorite sea vegetable to vegetable dishes, salads, and miso soups. They are easy to add to dishes as they require no cooking (see Tips for Preparing Sea Vegetables in the How to Enjoy section below). It is recommended to include 1 tsp of sea vegetables to your Healthiest Way of Eating each day.

Sea Vegetables, dulse, dried
1.00 TBS
(5.00 grams)
Calories: 11
GI: low

NutrientDRI/DV

 iodine500%

 vitamin C16%

 manganese16%

 vitamin B211%

 vitamin A9%

 copper9%

 protein4%

 phosphorus3%

 iron3%

 potassium3%

 zinc3%

 vitamin B33%

 vitamin B63%

 vitamin B13%

 pantothenic acid3%

Health Benefits

Why would anyone want to eat sea vegetables? Because they offer one of the broadest ranges of minerals of any food, containing virtually all the minerals found in the ocean—and not surprisingly, many of same minerals found in human blood. The also offer a variety of unique phytonutrients, including their sulfated polysaccharides (also called fucoidans). Unlike some other categories of vegetables, sea vegetables do not appear to depend on carotenoids and flavonoids for their antioxidant benefits, because in additional to these two important categories of antioxidants, sea vegetables contain several other types, including alkaloid antioxidants.Sea vegetables are an excellent source of iodine, vitamin C, manganese, and vitamin B2. They are also a very good source of vitamin A (in the form of carotenoids) and copper as well as a good source of protein, pantothenic acid, potassium, iron, zinc, vitamin B6, niacin, phosphorus, and vitamin B1.

Multiple Benefits from Sulfated Polysaccharides in Sea Vegetables

To understand many of the anti-inflammatory, anti-cancer, anticoagulant, antithrombotic, and antiviral properties of sea vegetables, you need to look no further than their sulfated polysaccharides. These unique compounds (also called fucoidans) are starch-like molecules that are unusual in their complexity. Unlike many other types of polysaccharides, the fucoidans contain many chemical "branch points," and they also contain sulfur atoms. Multiple studies show anti-inflammatory benefits from consumption of the sulfated polysaccharides in sea vegetables. Some of these benefits appear to take place through the blocking of selectins and from inhibition of an enzyme called phospholipase A2. Selectins are sugar-protein molecules (glycoproteins) that run through cell membranes. During inflammatory responses by the body, selectins are important in allowing inflammatory signals to be transmitted through the cell. By blocking selectin function, some of the inflammatory signaling can be lessened. In case of chronic, unwanted inflammation, this blocking of selectin-related signals can provide important health benefits. Interest in this aspect of sea vegetable intake and anti-inflammatory benefits has received special focus in the area of osteoarthritis. More widely present in unwanted inflammatory problems is overactivity of the enzyme phospholipase A2 (PLA2). This enzyme is important for creation of the omega-6 fatty acid called arachidonic acid (AA), and AA is itself the basic building block for a wide variety of pro-inflammatory messaging molecules. Many corticosteroid medications lower inflammation by blocking PLA2, as does licorice, turmeric, and the flavonoid quercetin. The association of sulfated polysaccharides with decreased PLA2 activity may be especially important in the anti-inflammatory benefits of sea vegetables.

Sea vegetables' sulfated polysaccharides are also associated with its anti-viral activity. Best studied in this area is the relationship between sulfated polysaccharides and herpes simplex virus 1 (HSV-1) and herpes simplex virus 2 (HSV-2). By blocking the binding sites used by HSV-1 and HSV-2 for cell attachment, sulfated polysaccharides help prevent replication of these viruses. It's important to point out that none of these HSV and sea vegetable studies have involved individuals with HSV who incorporated sea vegetables into their diet. Instead, the studies have been conducted in the lab using human fibroblast cells inoculated with HSV. We don't yet know whether dietary sea vegetables will help prevent HSV replication in individuals with HSV, even though we greatly look forward to future research results obtained in clinical studies with individuals who have HSV and add sea vegetables to their diet.

Many of the cardiovascular benefits of sea vegetables can also be attributed to their sulfated polysaccharide content. Extracts from sea vegetables are sometimes referred to as "heparin-like extracts" because they exhibit some of the same properties as this widely used anticoagulant medication. In fact, heparin itself can be described as a sulfated polysaccharide, and like the sulfated polysaccharides found in sea vegetables, it can decrease the tendency of blood platelet cells to coagulate and form clots. (A blood clot can also be called a "thrombus"—thus giving rise to the term "antithrombotic" in description of sulfated polysaccharides.) In addition to their anticoagulant and antithrombotic benefits, however, sea vegetables have also been shown to help lower total cholesterol and LDL cholesterol and to improve cardiovascular health in this way.

Anti-Cancer Benefits of Sea Vegetables

Not fully understood but of increasing interest to researchers are the anti-cancer benefits of sea vegetables. Research interest in this area has tended to focus on colon cancer, with a special emphasis on the loss of calcium-sensing receptors (CaSRs) in colon cancer cells, and the ability of sea vegetable extracts to alter CaSR-related events. But since chronic, unwanted inflammation and chronic oxidative stress are both risk factors for development of cancer, it would be quite natural for scientists to be interested in sea vegetables are anti-cancer foods not only in the case of colon cancer, but for other types of cancer as well. Sea vegetables are well-researched as containing a variety of anti-inflammatory and antioxidant compounds, and this nutrient combination is likely to result in some risk-lowering benefits in the case of colon cancer and other cancer types. Although much more research is needed in this area, we expect the anti-caner benefits of sea vegetables to become more firmly established over time.

Of special note in this area of cancer and sea vegetables is the issue of estrogen-related cancers, especially breast cancer. Intake of sea vegetables appears able to modify various aspects of a woman's normal menstrual cycle in such a way that over long periods of time (tens of years) the total cumulative estrogen secretion that occurs during the follicular phase of the cycle gets reduced. Since overproduction of estrogen can play a role in the risk of breast cancer for women who are estrogen-sensitive, sea vegetables may offer unique benefits in this regard. It's also important to note that cholesterol is required as a building block for production of estrogen, and intake of sea vegetables has repeatedly been shown to lower blood levels of total cholesterol and LDL-cholesterol.

Other Benefits of Sea Vegetables

Array of Minerals

Sea vegetables have been rightly singled out for their unique mineral content. You're going to find measurable amounts of calcium, copper, iodine, iron, magnesium, manganese, molybdenum, phosphorus, potassium, selenium, vanadium, and zinc in sea vegetables, and in some cases (like iodine) you can simply not find a more concentrated mineral source. Brown algae like kombu/kelp, wakame, and arame can be particularly concentrated sources of iodine, and for some health conditions - like hypothyroidism, in which the cells of the thyroid make too little thyroid hormone - increased iodine intake can provide important health benefits. The wide variety of minerals found in sea vegetables is simply not found among most other vegetable groups.

The vanadium content of sea vegetables is an area of special interest with respect to their mineral content. While research in this area remain inconclusive, sea vegetables may be able to help us increase our cells' sensitivity to insulin, help us prevent overproduction of glucose by our cells, and help us take existing blood sugars and convert them into storable starches. All of these factors would help us increase our blood sugar control, and lower our risk of type 2 diabetes.

Sea Vegetables' Concentration of Iron

Sea vegetables may turn out to be a better source of bioavailable iron than previously thought. One tablespoon of dried sea vegetable is likely to contain between 1/2 milligram and 35 milligrams of iron. At the lower end of this range, the iron content of sea vegetables is not really significant. But at the higher end of this range, the amount of iron found in sea vegetables is outstanding. (As an overall iron rating in our food rating system, we describe sea vegetables as being a "good" source of iron.) The iron found in sea vegetables 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.

Antioxidant Potential of Sea Vegetables

The antioxidant content of sea vegetables also deserves mention with respect to its health benefits. While sea vegetables do contain measurable amounts of polyphenols like carotenoids and flavonoids, they also contain other phytonutrient antioxidants, including several types of alkaloids that have been shown to possess antioxidant properties. Coupled with measurable amounts of antioxidant vitamins (like vitamins C and E) and antioxidant minerals (like manganese and zinc), sea vegetables can be expected to help us reduce our risk of unwanted oxidative stress and many types of cardiovascular problems that are associated with poor antioxidant intake.

Description

Western cultures are only recently beginning to enjoy the taste and nutritional value of sea vegetables, often referred to as seaweed, which have been a staple of the Japanese diet for centuries. Numerous various varieties of sea vegetables can be found in health food and specialty stores throughout the year. Owing to their rise in popularity, they are also becoming much easier to find in local supermarkets as well.

Sea vegetables can be found growing both in the marine salt waters as well as in fresh water lakes and seas. They commonly grow on coral reefs or in rocky landscapes and can grow at great depths provided that sunlight can penetrate through the water to where they reside since, like plants, they need light for their survival. Sea vegetables are neither plants nor animals but classified in a group known as algae.

There are thousands of types of sea vegetables, which are classified into categories by color, known either as brown, red or green sea vegetables. Each is unique, having a distinct shape, taste and texture. Although not all sea vegetables that exist are presently consumed, a wide range of sea vegetables are enjoyed as foods. Because Japan remains one of the world's largest sea vegetable producers and exporters, the Japanese names for sea vegetables are among the most common names found in grocery stores throughout the United States. The words we use to describe most commonly eaten sea vegetables like nori, hijiki, wakame, arame, and kombu are Japanese. Dulse, however, is of Gaelic origin.

Many people aren't sure exactly what is meant by the word "kelp," even though they associate it with sea vegetables. This word is often used very loosely to refer to any type of sea vegetable. However, when it's used in a scientific way, the word "kelp" refers specifically to the family of large brown algae and specifically to a variety of brown algae species that are found within the genus Laminaria.

Here is a little more information about some of the most popular types of sea vegetables: Nori: dark purple-black color that turns phosphorescent green when toasted, famous for its role in making sushi rolls Kelp: light brown to dark green in color, oftentimes available in flake form Hijiki: looks like small strands of black wiry pasta, has a strong flavor Kombu: very dark in color and generally sold in strips or sheets, oftentimes used as a flavoring for soups Wakame: similar to kombu, most commonly used to make Japanese miso soup Arame: this lacy, wiry sea vegetable is sweeter and milder in taste than many others Dulse: soft, chewy texture and a reddish-brown color

On the science side of the equation, here is a brief chart showing basic types of sea vegetables and some of their most commonly eaten varieties:

Sea Vegetables From a Science Standpoint

Green AlgaeBrown AlgaeRed Algae
Scientific NameChlorophycophytaPhaeophycophyta Rhodophycophyta
Approximate Number of Species 7,0004,0002,000
Commonly Eaten Formssea lettucekombu/kelp (Laminaria genus)nori (Porphyra genus)
wakame (Undaria genus)agar-agar (Euchema genus)
arame (Eisenia genus)dulse (Palmaria genus)
hijiki (Hijikia genus)
Other Well-Studied FormsCaulerpa genus, Ulva genus, Chetomorpha genus Sargassum genus, Padina genus, Fucus genus (Atlantic brown kelp, also called bladderwrack)Euchema genus, Gracilaria genus, Gelidiella genus, Plocamium genus, Lithothamnium genus, Kappaphycus genus

History

The consumption of sea vegetables enjoys a long history throughout the world. Archaeological evidence suggests that Japanese cultures have been consuming sea vegetables for more than 10,000 years. In ancient Chinese cultures, sea vegetables were a noted delicacy, suitable especially for honored guests and royalty. Korea, Vietnam, and Malaysia are other Asian countries where sea vegetables are widely consumed. Yet, sea vegetables were not just limited to being a featured part of Asian cuisines. In fact, most regions and countries located by waters, including Scotland, Ireland, Norway, Iceland, New Zealand, the Pacific Islands and coastal South American countries have been consuming sea vegetables since ancient times.

How to Select and Store

Look for sea vegetables that are sold in tightly sealed packages. Avoid those that have evidence of excessive moisture. Some types of sea vegetables are sold in different forms. For example, nori can be found in sheets, flakes, or powder. Choose the form of sea vegetables that will best meet your culinary needs.

At WHFoods, we encourage the purchase of certified organically grown foods, and sea vegetables are no exception. Repeated research studies on organic foods as a group show that your likelihood of exposure to contaminants such as pesticides and heavy metals can be greatly reduced through the purchased of certified organic foods, including sea vegetables. If you are shopping in a large supermarket, your most reliable source of organically grown sea vegetables is very likely to be sea vegetables that display the USDA organic logo.

Store sea vegetables in tightly sealed containers at room temperature where they can stay fresh for at least several months.

How to Enjoy

A Few Quick Serving Ideas

Make homemade vegetable sushi rolls by wrapping rice and your favorite vegetables in sheets of nori.

Slice nori into small strips and sprinkle on top of salads.

Combine soaked hijiki with shredded carrots and ginger. Mix with a little olive oil and soy sauce

  • Shiitake Mushroom Seaweed Soup
  • Spicy Healthy SautéedTofu
  • Cucumber Seaweed Salad
  • Kale with Hijiki
  • Seaweed Rice

    If you'd like even more recipes and ways to prepare sea vegetables the Nutrient-Rich Way, you may want to explore The World's Healthiest Foods book.

    Safety

    Sea vegetables have been a topic of ongoing debate and research concern involving heavy metals. In the world of marine biology and marine ecology, sea vegetables are widely recognized as plants with an excellent ability to take up minerals from the water and hold onto these minerals in their cells. This ability makes sea vegetables a rich source of many wonderful minerals, including magnesium, calcium, iron, and iodine. However, in waters that have become polluted with heavy metal elements—including arsenic, lead, and cadmium - sea vegetables can also act like a sponge in absorbing these unwanted contaminants. Some marine ecologists actually use sea vegetables as a kind of "biomonitor" to determine levels of heavy metal pollution in bodies of water.

    Among all of the heavy metals, arsenic appears to be most problematic when it comes to sea vegetable toxicity risk. Virtually all types of sea vegetables have been determined to contain traces of arsenic. These types include arame, hijiki, kombu, nori, and wakame. Among all types of sea vegetable, however, hijiki stands out as being particularly high-risk when it comes to arsenic exposure. During the period 2000-2005, government-related agencies in England, New Zealand, and Canada issued public health recommendations advising against consumption of hijiki sea vegetable unless verified as containing very low levels of inorganic arsenic. Based on these reports, we recommend avoidance of hijiki as a sea vegetable unless available in the form of certified organic hijiki.

    Although regulations for sea vegetables at the National Organics Program at the U.S. Department of Agriculture (USDA) are in a state of partial review, there are two types of certified organic sea vegetables currently available in the marketplace. Some certified organic sea vegetables have been farmed in a process that's usually referred to as "aquaculture" or "mariculture" and that involves a closely-monitored, contained-water environment for the sea vegetables. Other certified organic sea vegetables have been wild-harvest, but typically in regions where ocean waters are better protected against contaminants. In both cases, you're much more likely to get a low level of contaminants like arsenic (or no arsenic contamination whatsoever) by selecting certified organic hijiki (or any other sea vegetable). To assure yourself of no arsenic contamination whatsoever, you'll need to find a certified organic product that reports lab testing on the packaging and specifically indicates an arsenic-free status.

    The levels of arsenic found in other types of sea vegetable have been relatively small. The U.S. Environmental Protection Agency (EPA) has set an oral Reference Dose (RfD) for arsenic exposure of 0.3 micrograms per kilogram of body weight per day. For a person weighing 154 pounds, that amount translates into 21 micrograms of arsenic. In research on sea vegetables, sea vegetable-containing supplements (like kelp supplements) are better studied than fresh sea vegetables, so it can be helpful to look at sea vegetable supplement data when trying to evaluate the arsenic risk from sea vegetables. In multiple research studies, the amount of arsenic present in one tablespoon (10 grams) of kelp has averaged about 4-5 micrograms, or approximately 20-25% of the RfD. While this level of arsenic intake is well beneath the EPA's threshold for daily oral intake, it may still be an amount that some persons wish to avoid. Your only guarantee for avoiding this arsenic exposure is to find and purchase sea vegetables that have been specifically tested for arsenic content and report arsenic-free contents on the packaging. As described earlier, you are also much more likely to get a low level of arsenic exposure (or no arsenic exposure at all) by selecting of certified organic sea vegetables.

    Because 20% of all foodborne disease is associated with seafood intake, and half of these seafood-related disease problems involve toxins from algae, it's also important to understand the relationship between sea vegetables (very large algae) and algae that occur in other forms. Harmful algal blooms (HABs), or what were previously referred to as "red tides," involve unwanted changes in the sea environment in which very small, one-celled algae become too plentiful. These small, one-celled algae come in the form of dinoflagellates and diatoms. These one-celled algae are capable of producing certain types of compounds (for example, saxitoxins) that can be harmful to humans. Filter-feeding shellfish (like oysters and clams) can ingest large amounts of these small, one-celled algae and can serve to pass on their potential toxins in more concentrated form to humans. "Shellfish poisoning" is the general name given to this set of events. While shellfish poisoning is an important health problem in and of itself, it is a different type of problem than the problem of potential heavy metal residues found in sea vegetables, and the toxin-related risks associated with shellfish poisoning should not be confused with heavy metal risks associated with sea vegetables.

    We continue to include sea vegetables among the World's Healthiest Foods because of their incredibly rich mineral content and other unique health benefits, and because the toxicity risks described above can be prevented through the purchase of certified organic sea vegetables! Because most certified organic sea vegetables can be purchased in dried form and reconstituted at home, they can often be ordered from outside of your local area and shipped to you at a relatively low cost.

    Nutritional Profile

    Introduction to Food Rating System Chart

    The following chart shows the nutrients for which this food is either an excellent, very good or good source. Next to the nutrient name you will find the following information: the amount of the nutrient that is included in the noted serving of this food; the %Daily Value (DV) that that amount represents (similar to other information presented in the website, this DV is calculated for 25-50 year old healthy woman); the nutrient density rating; and, the food's World's Healthiest Foods Rating. Underneath the chart is a table that summarizes how the ratings were devised. Read detailed information on our
    Food and Recipe Rating System.

    Sea Vegetables, dulse, dried
    1.00 TBS
    5.00 grams
    Calories: 11
    GI: low
    NutrientAmountDRI/DV
    (%)
    Nutrient
    Density
    World's Healthiest
    Foods Rating
    iodine750.00 mcg500829.5excellent
    vitamin C12.16 mg1626.9excellent
    manganese0.31 mg1625.7excellent
    vitamin B20.14 mg1117.9excellent
    vitamin A81.05 mcg RAE914.9very good
    copper0.08 mg914.7very good
    protein1.81 g46.0good
    pantothenic acid0.16 mg35.3good
    potassium110.96 mg35.3good
    iron0.56 mg35.2good
    zinc0.33 mg35.0good
    vitamin B60.05 mg34.9good
    vitamin B30.46 mg34.8good
    phosphorus18.05 mg34.3good
    vitamin B10.03 mg34.1good
    World's Healthiest
    Foods Rating
    Rule
    excellent DRI/DV>=75% OR
    Density>=7.6 AND DRI/DV>=10%
    very good DRI/DV>=50% OR
    Density>=3.4 AND DRI/DV>=5%
    good DRI/DV>=25% OR
    Density>=1.5 AND DRI/DV>=2.5%

    References

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