Algae

Algae

The algae constitute a large group of ‘primitive’ plants – they do not reproduce by seeds as in most medicinal and food plants but rather by spores, and the plant body is not divided into root, stem, and leaf, but is in the form of a relatively undifferentiated ‘thallus’.

O R I G I N   A N D   C U LT I VAT I O N
They are mainly aquatic, being found in freshwater ponds, rivers, and lakes, and are the seaweeds found on shores all over the world. Total seaweed usage alone amounts to about 3.5 million tons per year. In Western countries seaweeds are harvested from their natural habitats, but in Asia there is quite a good deal of planned cultivation (e.g. see Porphyra below). Although microscopic algae (Chlorella and Spirulina)may be harvested naturally, today they are usually cultivated commercially.

P L A N T   D E S C R I P T I O N
Algae are classified according to their pigments. All algae contain the green pigment chlorophyll; the group known as the green algae contains only chlorophyll, but other groups have pigments in additionto chlorophyll. In the brown algae(seaweeds) the additional pigment is fucoxanthin. In the red algae (seaweeds) it is
phycoerythrin (red) and phycocyanin (blue) – the relative quantities vary, so different species vary in colour from red to bluish green; in the blue-green algae the only extra pigment is phycocyanin. There is also great
variation in size between species of the algae. Some are microscopic (unicellular and filamentous), whereas some seaweeds attain a length of 50 m (165 ft).

Spirulina (a blue-green alga)
A microscopic, fresh-water alga found as corkscrew-like filaments. In the sixteenth century Spanish explorers
found Aztecs harvesting a ‘blue mud’, probably consisting of Spirulina, from Lake Texaco (Mexico). This was dried and turned into chips and loaves. Similarly, the alga has been collected by local people from Lake Chad (Africa). Spirulina is still harvested from freshwater sources, but it is also cultured commercially in California, Thailand, India, and China. Presumably, it should be easier to produce a purer harvest from cultured material, rather than a natu-ral source where other algae might be present. The commercial product (the alga has been dried) con-tains: (a) 60–70% protein with a good amino acid profile; (b)16–20% carbohydrate; (c) 2–3% fat; (d) 7–9% water; (e) 5–8% minerals, including iron, calcium, and many others; and (f) vitamins: beta-carotene (provitamin A) and some of the B complex, including, as reported, B12, E, and K. The iron
present is easily absorbed by humans, which is not always the case with iron from other plant sources. Vitamin B12is not normally found in plant foods, only animal sources – a possi-ble problem for vegetarians and vegans. However, as with Chlorella and seaweeds, there is considerable doubt about the
nutritional significance of B12recorded for Spirulina. Spirulina presents a good nutritional profile, but it is far
more expensive than some animal foods (e.g. meat, milk), which may not worry vegetarians.

Chlorella (a green alga)
A microscopic unicellular alga, up to about 10 µm (1 µm = 0.001 mm) in diameter. In many other respects it is similar to Spirulina. Commercial cultivation takes place, and its nutritional profile is roughly the same.
Both Spirulina and Chlorella are available as tablets in health food shops.

Seaweeds
The term ‘kelp’ is applied to a number of seaweed species. In many parts of the world seaweeds, often dried, are used directly in food – as vegetables, and in salads and soups. They are sometimes sold in health food shops, supermarkets, and similar establishments. The greatest usage is in the Orient; e.g. in Japan some 50 species are utilized. Phycocolloids (carbohydrates) such as agars, alginates, and carrageenans are extracted from seaweeds and used as thickeners and stabilizers in a vast array of foods, including canned commodities, confectionery, ice-cream, jellies, soups, and sauces. Generally speaking, seaweeds contain protein (amino
acid profile similar to that of legumes), little fat, and some vitamins and minerals. Among the vitamins, B12has been recorded but, as in Spirulina, its biological activity is open to debate. Of the minerals present, the relatively high concen-tration (0.07–0.76% dry weight) of iodine is of interest. Seaweeds in the diet provide fibre.
Below is information on some of the utilized seaweeds:

● Laver (Porphyra umbilicalis): a red seaweed, found on the rocky shores of the UK and other temperate North
Atlantic countries. Its product is ‘laver bread’, particu-larly popular in south Wales but also eaten elsewhere.
Porphyra is popular in China, Korea, and Japan (where it is known as nori). The Japanese culti-vate Porphyra by sinking bundles of bamboo canes, brushwood, or nets offshore, to which will become attached a crop of the seaweed.

● Dulse (Palmaria palmata syn. Rhodymenia palmata): a red seaweed, consumed in the ways already described.

● Carrageen or Irish Moss (Chondrus crispus): a red seaweed collected commercially in Canada for carrageenan extraction. Small quantities are harvested in Ireland and France, and utilized as described on p. 2.

● Knotted wrack (Ascophyllum nodosum): a brown seaweed common in temperate Atlantic countries. It is harvested in Ireland, Scotland, and Norway for alginate extraction.

● Some other seaweed species utilized belong to Laminaria (in Japan known as kombu), Macrocystis, Nereocystis, Fucus, Gelidium (one source of agar), and Undaria (Jap. wakame).
Taking Laminaria (kelp) as an example of a seaweed, the nutrient analysis of fresh material is: water 81.6%; protein 1.7%; total fibre1.33%; fat 0.6%; energy 43 kcal; 233 mg sodium; 168 mg calcium; 89 mg potassium;
2.9 mg iron; vitamin B10.15 mg; vitamin B2 0.47 mg; vitamin C 0.1 mg.

C L A I M S   A N D   F O L K L O R E
Spirulina, Chlorella, and kelp tablets are readily available. Kelp refers to a number of species, but
usually to brown seaweeds. A considerable number of claims for the therapeutic value of Spirulina and Chlorella have been made, particularly on the Internet; one claim concerns the presence of vitamin B12, normally found in animal tissues. Similarly, kelp products have been used to treat a large array of complaints, including obesity, rheumatism, arthritis, indigestion, constipation, and other problems. These treatments have often been related to the high concentration of iodine in seaweeds. The phycocolloids (gels) present have a bulking effect in
laxative preparations, and a demulcent action.

E V I D E N C E
As stated earlier, the vitamin B12reported for Spirulina,Chlorella, and seaweeds is not considered biologically active. The value of iodine as regards therapeutic claims for seaweed should be treated cautiously. Iodine is required by the thyroid gland to form the hormone thyroxine, which controls body metabolism. Deficiency leads to goitre, but in many countries this has been eliminated by fortification, such as by the use of iodized salt. However, deficiency of iodine can occur and kelp could provide the necessary iodine, but professional advice is required because too much iodine (above 150 µg per day) can lead to hyperthyroidism (weight loss, sweating, fatigue, and other symptoms). Iodine in kelp has somehow been related to the
use of the product as a slimming aid in dealing with obesity. There seems little scientific support for this claim.
Seaweeds may absorb and concentrate unacceptable heavy metals, such as cadmium and lead, from contami-
nated sea water. Ingestion of kelp has been associated with the development of human acne.
Considering all the evidence, careful thought should go into the use of algal products. The therapeutic employ-
ment of kelp is not supported in Germany, and it should not be given during pregnancy and lactation.