Over the past few decades an increasing number of people have had access to sufficient food. But having enough food does not necessarily equate with it having balanced food. Many people in developing countries may get their calories, but proteins, vitamins and minerals are a different story altogether. Due to a lack of variety and the monotonous diet, between one and two billion people suffer from deficiencies of essentialnutrients such as vitamin A, iron and zinc. These deficiencies affect the immune system and restrict growth and cognitive development.
This hidden hunger is often combated by using pills and capsules (supplements) that have a direct effect in the short term, or by fortifying centrally processed foodstuffs such as salt, sugar and oil. Diversification of food, for instance y stimulating the development of vegetable plots or livestock owner ship, could also help. However, this is not an option for most farming families who only eat their own-grown crops and have insufficient financial means to purchase new crops or basic food products. Poor city dwellers (or others without land) are even more commonly left to a monotonous unbalanced diet. A good solution would be to build the required mine rals into the food crops that these people eat in large portions on a daily basis. This process, called biofortification, is a combination of (classic) breeding and cultivation techniques that result in the required quality.
Iron and zinc deficiencies
Ellis Hoffland, personal professor at the sub-department of soil quality is one of the scientists involved in soil science, crop physiology, food microbiology and food & health who have formed an alliance to find ways to solve iron and zinc deficiencies along the trajectory from soil to mouth. Although iron and zinc is almost always present in the soil (with the exception of a few regions in Australia), crops often have difficulty absorbing these minerals as they cannot extract it given the form in which it is bound to the soil particles. This situation affects a third of the global agriculture acreage.
So which crops perform best in such unfavourable conditions? The Wageningen scientists discovered that one rice variety was able to absorb 1.5 times more minerals from the soil than another. Choosing the right rice variety can therefore make an enormous difference. At the same time it was shown that only a small percentage of the extra absorbed zinc, even if it was further increased by means of fertilisation, ended up in the rice grain. In other words, the yields and mineral absorption from the soil increased, but the nutritional value of the rice grain showed only marginal improvement.
This is the opposite of the findings in sorghum or wheat. Breeding is therefore only useful if it improves the internal distribution of the available minerals. The solution can also be sought further down the chain; for instance by reducing the extent to which the rice grains are polished so as to maintain the iron in the germ. The husking and polishing of rice in particular is often centralised. The industry in China, however, seems reluctant to switch to better polishing methods as it requires a considerable investment in new equipment. This would make the rice more expensive and thus unattainable for people who need the minerals most. The people who can afford it generally do not suffer from deficiencies as they have a more varied diet. Food quality is unfortunately difficult to market, even if less polishing would result in effectively more saleable rice that could partially cover the costs.
In Africa, scientists achieved promising results with fertilising sorghum. The availability of Zn-enriched fertilisers is still a major issue in these regions, however. The new challenge is to make the minerals absorbed by the crop better available to people – the positively charged minerals in all grain crops are linked to phytate and stored as a mineral supply for after germination. In the germination process, the seeds use an enzyme to provide access to the required nutrients. This enzyme is unfortunately not present in the human stomach, and we can absorb much less iron and zinc from seeds than they actually contain. One of the solutions for neutralising the phytate blockage is allowing the grain to germinate or ferment. This looks to be a good option for sorghum in West Africa, as the locals are used to ferment their food. In sorghum, iron and zinc molecules also form a compound with tannins. This effect can be undone by means of fermentation, but if the fermentation is followed by heating for a different part of the preparation process, the minerals are locked up once again. This therefore requires the selection of tannin-deficient varieties.
But even if these results stand up, it is unwise to place all one’s egg in a single basket and bet solely on breeding, according to crop physiologist Tjeerd Jan Stomph, who is part of the research team: “Biofortification by means of genetics may be the solution in some regions and for the long term. In others – and in the much shorter term – fertilisation may have much better results. Sometimes food
technology may be the way to achieve our goals. An optimal effect can be reached by improving
conditions at all parts of the chain. For the same reason it is ineffective to be fixated on a deficiency
of a single mineral as the function of nutrients is connected by means of numerous interactions.
Adding zinc also improves iron retention.” “There is still much to discover about the exact functioning of minerals. It is important that – in fighting hunger – we do not only focus on the quest for ‘more’ but also strive for ‘better’ food. Quality is at least as important as quantity.”
To test whether rice breeding is actually useful, scientists determined the bio-availability of zinc from rice that was enriched through biofortific tion in a natural way. In cooperation with a Chinese institute and the Swiss ETH, it was found that with higher concentrations of zinc in polished white rice the human body absorbs the same percentage as from non polished standard rice.