Tanned tomatoes
Tomatoes with a high content of provitamin D were obtained
Anna Novikovskaya, Naked Science
Around the world, about a billion people suffer from a lack of vitamin D3, which is vital for the normal development of bones, the protection of teeth and the functioning of the immune system. Now they will have the opportunity to make up for its lack by eating genetically modified tomatoes.
Hunger is still one of the main problems of humanity. About a third of the world's population suffers from a lack of vitamins and minerals in food, and especially this "hidden hunger" affects the population of developing countries, which leads to significant socio-economic consequences. The most common deficiency is iron, zinc, provitamin A, folic acid and iodine: the lack of these substances leads to the development of various diseases, including cancer, and general deterioration of health.
Currently, the deficiency of vitamins and minerals is most often replenished with the help of dietary supplements, for example, vitamin capsules for children, and fortified foods like iodized salt, – however, nutritionists place the greatest hopes on expanding the diet and increasing the content of useful trace elements in agricultural crops.
In the context of global climate change, we are increasingly talking about a complete change of the food system, which should now be aimed not only at providing humanity with food, but also at preserving fragile natural ecosystems. With the help of biotechnological methods, it is possible to reduce human dependence on animal products by increasing the nutritional value of plants: for example, rapeseed (Brassica napus) with an increased content of omega-3 fatty acids has been obtained relatively recently, which can serve as an alternative to fish oil.
In a new article published in Nature Plants (Li et al., Biofortified tomatoes provide a new route to vitamin D sufficiency), an international team of scientists reported the receipt of bio-enriched tomatoes with an increased content of vitamin D3. This vitamin plays a key role in the absorption of calcium and phosphorus, and also increases the body's resistance to viral diseases. Its deficiency can lead to childhood rickets, osteomalacia and osteoporosis; in addition, there is evidence of the effect of the lack of this vitamin on the development of neurological, cardiovascular, viral and autoimmune diseases, as well as cancerous tumors.
Although vitamin D3 can be produced in human skin under the influence of ultraviolet radiation, being in direct sunlight increases the risk of skin cancer, and the effectiveness of vitamin production strongly depends on the availability of sunscreens and skin type. As a result, it is much safer to make up for the lack of this vitamin by eating foods enriched with 7-dehydrocholesterol (7-DHC), provitamin, which in our body spontaneously isomerizes into cholecalciferol, or vitamin D3.
Provitamin 7-DHC is present in the leaves and unripe green fruits of tomato (Solanum lycopersicum), but in ripe tomatoes it is already very little. The authors "corrected" the genes responsible for the conversion of 7-DHC into cholesterol, blocking this metabolic pathway – and provitamin began to accumulate in ripe tomatoes. As a result, the modified tomatoes obtained in this way contained up to 2 micrograms of 7-DHC, which, when irradiated with UV light, safely turned into vitamin D3. The modified plants did not show significant changes in the morphology or composition of the fruits, and with an alternative modification of the genome, it is possible to obtain tomatoes containing up to 10 micrograms of 7-DHC – that is, to ensure the daily needs of the body in vitamin D3, it will be enough to eat one or two fruits.
Unfortunately, it is still a long way from obtaining modified plants to their mass introduction into production: first we will have to assess how well provitamin is preserved in ripe fruits during storage and processing, how well it is absorbed by the human body and whether the intervention of genetic engineers has affected the physiology of the plant, in particular, its stress resistance. The latter factor may be the most important, because in a changing climate, agricultural plants are increasingly negatively affected, but the new study is in any case an extremely important step towards providing the population with full–fledged food.
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