Sugar kelp

What is Sugar kelp?

Sugar kelp is a large brown seaweed from cold northern seas. Its botanical name is Saccharina latissima. In Iceland and Norway it is known as beltisþari, or belt kelp, after its long strap-shaped frond.

People eat it as a vegetable and use it as a salty seasoning. It is sold fresh, dried, as flakes, as powder and in capsules. Coastal farmers have fed it to sheep and cattle for centuries.

Here is the honest verdict. Sugar kelp is a real food with real nutrients, above all iodine. Its long use in Scandinavia is not proof that it treats any illness, and it is not proof that it is safe for everyone.

The iodine is the main thing to watch. Your thyroid, a gland in the neck, is sensitive to how much iodine you get. Sugar kelp can deliver many times a day's need in a small amount.

How does Sugar kelp work?

The one clear, proven effect is that sugar kelp supplies iodine. Your thyroid needs iodine to make the hormones that set your body's pace. Too little iodine causes goitre, a swelling of that gland.

More is not better. Large amounts of iodine can push the thyroid too fast or too slow. This is well documented in people who eat a lot of seaweed.

The other proposed actions are far less certain. Alginate, the main fibre in kelp, forms a gel in the stomach. In small human trials, alginate drinks have slowed stomach emptying and trimmed appetite a little, with mixed results.

In test tubes and in animals, kelp fibres appear to slow the enzymes that break down starch and fat. Whether that changes blood sugar in people who eat kelp is not established.

Fucoidan, another seaweed fibre, appears to thin blood and damp inflammation in laboratory work. That has not been shown in people eating ordinary amounts of kelp.

What forms does Sugar kelp come in?

Dried fronds are the classic form. They are simmered in broth or soaked and sliced, much as kombu is used.

Flakes, powder and kelp seasoning salts are common in shops. People sprinkle them on food in place of table salt.

Fresh sugar kelp is sold near the coast in season. It is blanched, pickled or added to salads.

Capsules and tablets of kelp powder are sold as supplements. These concentrate the iodine, so the amount per pill can be high and uneven between brands.

Alginate drawn from kelp appears in ice cream, sauces and wound dressings. Kelp extracts also turn up in bath salts, soaps and skin creams.

Sugar kelp is farmed on ropes along Norway, Denmark, Iceland and Scotland. Farmed kelp is usually cleaner and better labelled than kelp you pick yourself.

Where it comes from:

Coastal Scandinavians have gathered kelp for well over a thousand years. Icelandic and Norwegian sources name beltisþari as food, animal fodder and a source of ash.

In lean years it stretched the food supply. Dried fronds were stored and boiled into soup or porridge.

Folk practice also linked seaweed to goitre, the neck swelling that comes from too little iodine. Coastal diets rich in seaweed and fish did carry far more iodine than inland diets.

Farmers fed kelp to sheep and cattle through the winter. In the 1800s, burnt kelp ash was a commercial source of soda and iodine.

Today sugar kelp is farmed in the Nordic countries as a crop. Chefs use it for stock and seasoning, much as earlier generations did.

What does Sugar kelp help with?

• Dietary iodine intake: This is the clearest effect. Sugar kelp raises iodine intake, and studies measuring iodine in urine confirm it. The catch is control. The amount per gram varies hugely between batches, so you cannot judge your intake from a spoonful. Iodised salt and fish give a steadier supply.
• Goitre caused by iodine shortage: Goitre from too little iodine is prevented by iodine, and seaweed is one source of it. That much is settled. But not all neck swelling comes from iodine shortage. Kelp can make some thyroid problems worse. A swollen neck needs a doctor's check, not self-treatment.
• Savoury seasoning and salt reduction: Tradition used kelp as a flavour base for broth and fish. Modern food research supports the taste part. Kelp flakes add a savoury, salty taste with less sodium than plain salt. Small taste trials show people accept lower-salt food seasoned this way. The iodine load still applies.
• Appetite and fullness: Claims that kelp curbs hunger rest mostly on alginate, its gel-forming fibre. Small, short human trials of alginate drinks show modest, mixed effects on fullness and food intake. Trials of whole sugar kelp are few and small. It is not a proven weight treatment.
• Blood sugar after meals: In test tubes and in animals, kelp extracts slow the enzymes that digest starch. A few small human trials of seaweed with a meal found slightly lower blood sugar peaks. The studies are short and used different products. This is not established enough to rely on.
• General mineral and fibre intake: Sugar kelp supplies fibre, potassium, calcium and magnesium as part of a meal. That is normal nutrition, not a remedy. No trial shows that adding kelp to a decent diet improves health outcomes.

Which foods are rich in Sugar kelp?

Sugar kelp is itself a food. It appears in Nordic broths, breads, crispbread, seasoning salts and pickles. Kombu dishes in Japanese cooking use close relatives with a similar iodine load.

What are the side effects of Sugar kelp?

• Strong fishy or metallic taste
• Bloating, wind and loose stools from the fibre
• Thirst and puffiness from the salt content
• Thyroid becoming underactive: tiredness, weight gain, feeling cold
• Thyroid becoming overactive: racing heart, shaking, weight loss
• Swelling at the front of the neck
• Acne-like iodine rash
• Allergic reaction, including itching or wheezing
• High potassium in people with kidney disease
• Build-up of cadmium or arsenic with heavy long-term use

Good to know:

Gut effects and taste complaints are the common ones, and they are mild.

Thyroid trouble is the serious one. It is not common with occasional food use. It has been reported again and again in people taking kelp pills daily for months.

Most of these thyroid cases settled after stopping kelp, but some people needed treatment. Pregnancy is the setting where excess iodine matters most, because it affects the baby's thyroid.

How much Sugar kelp should you take?

• Recommended daily: No personal amount is given here, because the right amount depends on your thyroid and your other iodine sources. Labels on kelp supplements usually state iodine per serving in micrograms. Many keep a serving near 150 micrograms. Some list 300 to 500, and a few list far more. Food packs of dried sugar kelp often carry a warning to use it sparingly. Nordic and EU guidance treats high-iodine seaweed as an occasional food, not a daily staple. If you have any thyroid condition, ask your doctor before using kelp at all.
• Best time of day: Time of day does not matter for kelp itself. Timing does matter around medicines. Thyroid tablets and kelp should not be taken together, and your prescriber can tell you how to space them.
• With or without food: Sugar kelp is a food, so it is normally eaten with meals. Its fibre may slow how fast other things are absorbed. Keep it well apart from medicines you take on an empty stomach.
• Time to effect: Iodine levels in the body shift within days to a couple of weeks. Any thyroid change usually shows up over weeks to months, and it can go either way. Effects on hunger or blood sugar, if they happen at all, would be within a single meal. For most health claims made for kelp, the honest answer is that it may do nothing.
• How long to take it: There is no agreed safe length of daily use. Iodine effects build up over weeks, so long daily use is the risky pattern. As a seasoning used now and then, kelp is treated like any other food. Daily supplement use over months is where reported thyroid problems cluster. Studies long enough to judge years of use do not exist.