Kelp Laminaria digitata Family: Laminariaceae CTFA: Fucus Vesiculosus Extract

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Photo © Steven Foster

Introduction

Kelp is found in cold waters near the shores of the northern Pacific and Atlantic oceans.¹  It is a large, brown perennial seaweed with flat, leaf-like fronds.^2,3,4  To remain stationary, kelp has adhesive like discs called holdfasts⁵  which affix to rocks near low tide levels.^2,3  

History and Cultural Significance

Kelp contains mostly water (82%), as well as protein (2%), fiber (2%), vitamins, minerals and small amounts of fat.⁶  It has variable amounts of the mineral iodine and a polysaccharide called sodium alginate⁴  that has the unique property of forming a thick gel in water which, when taken orally, can provide laxative effects.⁷  In addition to its historic use as a bulk laxative, kelp has been used traditionally for weight loss and indigestion.⁴  

Many of the beneficial properties of kelp have been attributed to its iodine content. Iodine is used to increase metabolism and fat burning properties.^4,8  The recommended daily allowance of iodine is quite small but long term iodine intake could have medical consequences such as hyperthyroidism so the use of kelp for weight loss over a long period of time is not recommended.⁴  

Alginates (natural gums obtained from kelp) are often used in the food industry to thicken or gel such products as ice cream.⁹  Algin’s industrial applications include use as an emulsifier (an additive that helps provide a smooth texture) in cosmetics, pharmaceuticals and paints.⁵  

Powdered kelp has been used as a salt replacement in many savory dishes such as seafood, beans, vegetables, and meat.¹⁰  In Japan and other countries powdered kelp is often used to make teas and soups.³  

In the 1800s kelp was used topically as a “tent” to aid in cervical dilation and to induce labor.⁷  A tent is any material that absorbs water and expands as a result.¹  

Modern Research

Currently there are no human clinical studies available on the external uses of kelp.

Future Outlook

China, Korea, Japan and the Philippines have well established seaweed farming and harvesting techniques. Annually, 7 million tons (wet weight) of seaweed, including kelp, are collected worldwide. Of these 7 million tons, 80% are cultured on seaweed farms. Seaweed used in domestic foods accounts for 70% of the farmed seaweed.¹¹  

In 1994 approximately 81,000 tons of kelp was harvested from California kelp beds.⁵  Only the top four feet of the fronds is harvested, leaving the holdfast to produce more kelp.

Storms, and other natural events, can have a significant effect on the amount of kelp available in an area over a very short period of time. El Niño conditions can aggravate the low kelp abundance after winter storms by reducing the growth of kelp. Harvesting kelp on a limited scale does not suggest any detectable adverse outcomes. Although over-harvesting of kelp has not yet been seen, studies have been performed trying to determine at what point repetitive harvesting could impact the ecosystem.⁵  

In 2001 the estimated dry tons of alginate harvested from kelp was 30,500 tons in Europe and 13,000 tons in the Asian Pacific. Presently the commercial demand for alginate is limited; however as the worldwide recession improves, alginate demands should increase. Dried kelp can be stored for long periods of time, thereby allowing processors to store the raw material until alginate demand increases.¹²