I wonder why so few foragers ask about pollen. Actually, the view on the nutritional availability of pollen to us varies extremely among nutritionists and I wanted to systematize it by quoting the available few sources.
In the nineteenth century Poland’s poor peasants had a term przednówek, i.e. “before-the-new” for spring starvation or food shortages. They were saving on the last stores of grain by collecting hazel (Corylus avellana) catkins covered by pollen (technically they are male inflorescences). These catkins were called rzęsy or rząsy (local name for eye-lashes). They added them to bread dough. This usually happened in March (or even February) but, later at the turn of March and April, people would also consume male catkins of sallow (Salix caprea) which were supposed to be good against colds (Łuczaj 2021).
Another pollen plant used for foraging is cattail (Typha). It produces a lot of pollen which has been used in some countries for food, i.e. in the Middle East, south-east Asia and by Maori in New Zealand and Native Americans in both North and South America (Prendergast et al. 2000). Also maize pollen was collected by the Indians (Prendergast et al. 2000)
Pollen is very rich in nutrients. The pollen of insect pollinated plants is more nutritious than this of wind pollinated plants but is much scarcer (Linskens and Jorde 1997). According to one study pollen contains 11% fat, 36% carbohydrates and 23% proteins, being similar to dry pulses (Linskens and Jorde 1997).
Typha dominegenis pollen is widely sold in southern Iraq round the confluences of the Tigris and Euphrates. This pollen mixed with sugar and steamed is known as kharet and sold in the souks of Kuwait (Prendergast et al. 2000). Typha is also known as food among the Maori of New Zealand, known there as pua (Prendergast et al. 2000). Maori would wrap leaves around the mixture of cattail pollen and water and steam it in a hangi (an earth oven). Colenso (1881) described the cooked cake as “sweetish and light, and reminds one strongly of London gingerbread”.
Pollen walls are made of two layers: intine and exine. Exine is extremely hard, but can have apertures: they are regions of the pollen wall that may involve exine thinning or a significant reduction in exine thickness. They enable shrinking and swelling of the grain caused by changes in moisture content. The digestive enzymes can enter pollen walls only through the apertures. Franchi (1997) carried out experiments on the digestion of hazel (Corylys avellana) and poppy (Papaver rhoeas)pollen. They were based on in vitro digestion with enzymes and environments similar to human digestive system (pepsin, papain and diastase, pancreatin and pancreatic lipase in optimial pH conditions). Hazel has relatively thin intine. After 24 treatment only 3% carbohydrates and 59% proteins in hazel pollen were digested. This shows the small availability of carobohyrates and relatively high availability of proteins. Only high pH treatment with pancreatic enzymes has an effect, whereas the acidic pH of stomach does not affect pollen.
Let’s look at bees, As Roulston and Cane (2000) write “Pollen digestion has been studied most extensively in bees, but a complex and somewhat confusing set of interpretations has emerged. Adult bees possess a crop, in which nectar and pollen may mix, thus providing a pre-treatment that could lead to germination or pseudo-germination. The crop leads through the proventricular valve to the gut, a region that differs substantially in osmotic pressure from the crop. Thus, pollen consumed by adult bees is subjected to immersion in a sugar solution followed by an abrupt osmotic gradient. In contrast, larval bees have no crop. Pollen enters the gut without internal exposure to nectar sugars or sudden changes in osmotic pressure. The pollen consumed by larval bees, however, is part of a food provision including a large quantity of nectar. Thus, larval pollen has been exposed to a liquid sugar environment prior to ingestion. For most bee species, larvae consume the pollen within a few ways of pollen collection. For honey bees, however, pollen may be stored in the hive for an extended period of time.”
The best way to enable the digestion of pollen is to cause germination and pseudo-germination by cracking pollen walls by osmotic pressure. No wonder in Iraq cattail pollen is mixed with sugar. Bees do it similarly storing the pollen with nectar. In Poland hazel catkins were used in sourdough bread which may also have had an effect on the digestibility of the pollen. The conclusion is the interior of pollen grains can be accessed by humans and partly digested. It can probably be highly increased by creating a high osmotic pressure storing the pollen in sugar (confirmed by traditional use) or salt (my hypothesis).
If you want to read about other Polish famine food, you are welcome to buy my book:
Prendergast, H.D., Kennedy, M.J., Webby, R.F. and Markham, K.R., 2000. Pollen cakes of Typha spp.[Typhaceae]-‘lost’and living food. Economic Botany, 54(3), pp.254-255.
Arenas, P. and Scarpa, G.F., 2003. The consumption of Typha domingensis Pers.(Typhaceae) pollen among the ethnic groups of the Gran Chaco, South America. Economic Botany, 57(2), pp.181-188.
Morton, J.F., 1975. Cattails (Typha spp.)—weed problem or potential crop?. Economic Botany, 29(1), pp.7-29.
Franchi, G.G., Franchi, G., Corti, P. and Pompella, A., 1997. Microspectrophotometric evaluation of digestibility of pollen grains. Plant foods for human nutrition, 50(2), pp.115-126.
Linskens, H.F. and Jorde, W., 1997. Pollen as food and medicine—a review. Economic Botany, 51(1), pp.78-86.
Roulston T.H. and Cane, J.H., 2000. Pollen nutritional content and digestibility for animals. Pollen and pollination, pp.187-209.
Colenso, W. 1881. On the vegetable food of the ancient New Zealanders before Cook’s visit.
Transac- tions and proceedings of the New Zealand Insti tute 13: 3-19
Łuczaj, Ł. 2021. Foraging in Eastern Europe: Wild edible plants in Polish traditional cuisine. Pietrusza Wola.
Many thanks to Kim Walker for sharing her photo of hazel catkins.