TUNAS: FOOD MEDICINE
Perla Marysol Peña Reséndiz
Prevention of disease
Photo from- Ancestral fruit of the Nopal and the most representative of México. (2021, 6 abril). [Fotography]. The Yucatán Times. https://www.theyucatantimes.com/2021/04/tunas-ancestral-fruit-of-the-nopal-and-the-most-representative-of-mexico/
Opuntia ficus-indica is a fruit of a shrub species of the Opuntia genus of the Cactaceae family, it is cultivated in all arid and semi-arid regions of the world. It is consumed fresh, and its derivatives are presented in juices, jams, fruits in syrup and liqueurs; beyond its forms of consumption, modern research has determined that the fiber contained fights against gastritis, heartburn, gastric ulcer and facilitates the absorption of cholesterol, the presence of fructose regulates sugar levels in the blood and an alkaloid called Cantina reduces heart problems, among others. The objective of this research is highlighting the numerous properties and applications of this fruit in terms of food medicine. In addition to emphasising their modes of production, which require little amounts of water and almost no use of chemical fertilizers, preventing soil erosion. Through a documentary study and theoretical-practical analysis, multiple solutions are proposed for the prevention and treatment of stomach and cardiovascular diseases, where the last one, represents one of the leading causes of death worldwide, hence the importance to spread its consumption. Thanks to this fruit, the quality of life of the human is improved, emphasizing that the best medicine is food.
The leaves Tuna, called “Nopalitos”, when they are between 9 months and two years old, produce cochineal, a fundamental element that helps to produce natural dyes that are used in different industries, the leaves are also used to feed field animals. This fruit is used as food to be consumed fresh; ripe fruit is industrialized into juices, jams, fruit in syrup, liqueurs, etc. 
It is a food of great nutritional value, as it provides vitamins, minerals, and proteins, it is juicy, healthy and with excellent properties for digestion due to the fiber contained in its seeds. Traditionally the Tuna has been used not only as food, but also as a natural remedy to treat multiple stomach diseases, colds, high cholesterol, as well as being an excellent food for diabetics. Several studies have suggested that the effectiveness of prickly pear in lowering blood sugar is its ability to bind with sugar in the intestine. Some researchers theorize that nopal may increase the cellular capacity to use insulin, offering healthy benefits to people with diabetes, as well as those with excess cholesterol. [1,2,6]
And in addition, the use of chemical fertilizers is almost nil, since the most used is compost. The mucilage present in its composition prevents the loss of water, making its production a sustainable action in accordance with objective 12 of the UN Agenda 20 - 30. [3.7]
Is the Tuna fruit capable to act as a nutraceutical food?
Promoting the consumption of the Tuna to improve human quality of life and to inform the ecological and sustainable balance that its production generates.
Literature Review / Concept & Definition.
A. Nutraceutical food
A nutraceutical food is one that provides medical or health benefits, including the prevention and / or treatment of disease. Due to the scientific knowledge of the beneficial properties, they possess, nutraceuticals have been associated with the prevention and treatment of at least three of the diseases that contribute to a high mortality rate in developed countries (diabetes, cardiovascular diseases and arterial hypertension) and in the prevention of others in certain stages of life such as osteoporosis. [8,9]
If we talk about their characteristics, we can define them as: "products of natural origin with active biological properties, beneficial for health and with defined preventive and / or therapeutic capacity". They must meet the following criteria:
Be products of natural origin, isolated and purified by non-denaturing methods to preserve their original properties without doing any type of chemical manipulation.
They must have beneficial effects on health: improvement of one or more physiological functions, preventive and / or curative action, and improvement of the quality of life, and provide temporary stability.
They must pass a stability and toxicology analysis and chemical analysis.
Reproducible studies of its bioactive properties must be carried out in experimental animals and in humans. [8,9]
B. Sustainable production
The sowing of large areas of Tuna’s production would allow the recovery and regeneration of the soil, the preservation of biodiversity in desert and semi-desert areas. It is an alternative to counteract global climate change and desertification. Other benefits from Opuntia are soil and water conservation, as well as the protection of local fauna in arid and semi-arid areas. Because it grows on severely degraded lands, its use is important due to its abundance in areas where very few crops can be grown be achieved. 
An additional product is mucilage or gum, obtainable by pressing the stem or cladode. It is a species widely used in agroforestry practices, associated with crops with agricultural and / or forage species, in thorny living fences, living barriers for soil retention, protection of slopes against erosion and, in general, as part of practices of soil protection. The cultivation of O. ficus indica slows down desertification and prevents soil erosion, but also consumes CO2 at night in large quantities, thus significantly reducing air pollution. For this reason, the planting of this species in city parks and gardens should be recommended. Its abilities to act as an anti-pollution agent to clean dirty water and as a substitute source of oil are being studied. [3,10,15]
Critical analysis of the literature.
The reason why it was decided to set the studies about the various applications of the Tuna properties, was to verify the importance of having a well-balanced alimentation from a different perspective we know, because by highlighting the role of this fruit as a nutraceutical food, gives us the opportunity to invest our capacities to still developing these amazing findings with the help of Biology, Chemistry and Technology. In this point of the investigation, we promote one of the main purposes “The best medicine is the food”.
It is worth mentioning that Mexico is the biggest producer of Tuna in the world, it has 20 thousand producers, who harvest 48 thousand hectares and obtain around 352 thousand tons per year. The highest volume of production is concentrated in the states of Mexico, Zacatecas, Puebla and Hidalgo. The harvest is carried out in the months that go from July to September, mainly. Mexico exports tuna to the United States, Canada and to a lesser extent to Chile, the Netherlands, Germany, Belgium and France.
Significance of the study.
Having in mind the diseases that afflict humans worldwide, regardless of age, the implementation of natural foods is the journey we will become healthier to reduce illnesses, also is the way we are going to prioritize the world problems by making sustainable options to get a balance between our necessities and disposition of resources.
2. RESEARCH METHOD
Documentary research with a meta-analysis axis was carried out where the benefits of the intervention of the Tuna fruit as a food medicine were analyzed. Many recent investigations were taken to analyze their content according to the purposes of this research.
a) TUNA’S PRODUCTION AS A SUSTAINABLE OPTION
Quantities of water used and water’s destiny.
Soil conditions during the production period.
Use or absence of use of chemical products as fertilizers.
b) COMPROBATION OF THE TUNA FRUIT AS A NUTRACEUTICAL FOOD
Natural origin of the fruit.
Presence of beneficial effects on health
Approve a stability and toxicology analysis and chemical analysis
Presence of studies about its bioactive properties carried out in experimental animals
and in humans.
3. RESULTS AND DISCUSSIONS
According to sections
The results obtained are the next:
(1) The hypothesis was approved. The Tuna fruit is capable of acting as a nutraceutical food.
The first parameter to determine this characteristic is the natural origin of the fruit, it’s more than known that the Tuna has a process of production in the field [2,3]. The second one is the presence of beneficial effects on health, it’s also exposed in this investigation the multiple applications of the fruit properties in favor of quality life, such as a regulator of sugar in the blood [4,5]. The third one talks about approving a stability and toxicology analysis and chemical analysis, in the research we got conscious about the effects of consumption of this fruit proving the absence of toxic substances in the fruit . And the last one is the presence of studies about its bioactive properties carried out in experimental animals and in humans, in this point all the results obtained required the experimentation in humans to verify the capacity of the objectives, also, having in mind that this fruit is part of the diet of many persons, the studies didn’t demand dangerous assays. 
Second parameter. Studies and results. 
Third parameter. Bromatological analysis Opuntia ficus-indica [3,11]
Fourth parameter. Bioactive properties.
(2) The fiber contained fights against gastritis, heartburn, gastriculcer, and facilitates the absorption of cholesterol.
Opuntia ficus indica cladodes are used for the treatment of gastric ulcers. Pre-treatment test in rats revealed a protective action against ethanol-induced ulcer, acute administration of O. ficus indica lyophilized cladodes generally maintains the cytoarchitecture of the gastric. The mucilage may prevent penetration of the necrotizing agent into the gastric mucosa. Moreover, it forms a protective layer and prevents the deep necrotic lesions induced by ethanol. The major components of O. ficus indica cladodes consist of a mixture of mucilage and pectin. The pectin polysaccharides from O. ficus indica cladodes probably may affect the gastrointestinal mucosa regeneration. O. ficus indica cladodes give rise to cytoprotection phenomena by breaking up the epithelial cells and stimulating an increase in mucus production in ethanol induce ulcer which tends to dissolve the components of the mucous membrane of the stomach and lowers the level of tissue protein, but preventive treatment with O. ficus indica cladodes can stop the ulcerogenic agent to prevent damage.  By this way, the capacity to reduce, in general terms, stomachal problems is observed.
On the other hand, it helps to eliminate excesses of cholesterol by the activity of amino acids, fiber, and niacin to metabolize fat and fatty acids, that’s how absorbed and accumulated fat in veins and arteries is prevented. 
(3) Fructose present regulates sugar levels in the blood.
It is considered an antidiabetic agent because it contains saponins, so the consumption of the Tuna fruit induces the body to obtain a greater sensitivity to insulin, which leads to a low elevation of blood glucose in people with diabetes. By increasing levels and sensitivity to insulin, it stabilizes and regulates the level of sugar in the blood .
In another study to evaluate whether Opuntia ficus indica stems or their raw preparations have hypoglycemic effects, 8 patients with non-insulin-dependent diabetes mellitus (NIDDM) were studied. Four different tests were performed on each patient after oral intake of 500 g of O. ficus indica. Serum glucose levels were measured at 0, 30, 60, 120 and 180 min. Glycemia decreased in all patients after ingestion of O. ficus indica and reached statistically significant levels after 120 and 180 min. The main hypoglycemic effect shown after O. ficus indica ranged between 23.3 ± 4.4 and 25.4 ± 14.3 mg / dL (mean ± SD) below glucose levels at 0 min. Concluding that Opuntia ficus indica exerts hypoglycemic effects in patients with NIDDM. Making it clear that the consumption of this fruit has benefits in health or not, promoting a better selection of foods 
The last studies carried out by the Rayat Institute of Pharmacy shows that Alloxan was administered as a single dose (130 mg/Kg BW) to induce diabetes. A single or repeated dose of cactus fruit juice (5ml per once, twice, three or four times/rat) was orally administered daily to alloxan-induced diabetic rats for five weeks. The levels of glucose, cholesterol, urea, creatinine, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and malondialdehyde (MDA) were significantly (P < 0.05) increased, while levels of superoxide dismutase (SOD), reduced glutathione (GSH), HDL cholesterol, protein, hemoglobin and liver glycogen were significantly decreased in serum of alloxan induced diabetic rats. Treatment of the diabetic rats with a single or repeated dose of cactus fruit juice could restore the changes of the above parameters to their normal levels (Hassan et al., 2011). [12,20]
(4) An Alkaloid called “Cantina” reduces heart problems.
The antioxidant compounds of fruits and vegetables can prevent oxidative damage in cells, thereby reducing the risk of cancer, cardiovascular diseases, neurodegenerative, diabetes, among others. In this case, the presence of the alkaloid Cantina, considered a cardiac tonic for increasing the strength and amplitude of the heart's contractions. [2,5,6] In this way we protect the organ that allows the rest to function, promoting the consumption of this fruit is how we obtain a healthier and stronger heart.
(5) Its production is sustainable and comply the 12th objective of the Agenda 20–30 of the UN.
Nowadays, the production of farm food requires the accomplishment of numerous rules and protocols to protect the environmental conditions of a determined area, also to make it sustainable, this way the erosion soil and water loss is avoided. In this investigation we could set the requirements of O. ficus production which are the following:
Quantities of water used and water’s destiny:
The Ecophysiology of O. ficus allows the plant to optimize the water present in water vapor through waxy cuticles on its stems to reduce its loss during photosynthesis. In addition, the stems contain a large volume of off-white spongy parenchyma that stores water, which acts as a reservoir for the chlorenchyma. As another adaptation, the roots of O. ficus-indica tend to be shallow, at an average depth of 15 cm, facilitating a rapid response to light rains. It can be concluded that O. ficus adapts to the environment to which it belongs and through its physiology makes its development possible with the amount of water available without wasting it. [3,15]
Soil conditions during the production period:
According with the section B in LITERATURE REVIEW, Tuna’s production allows the recovery and regeneration of the soil, the preservation of biodiversity and local fauna in arid and semi-arid areas thanks to its natural and rigorous mechanism to consume what it needs. [3,10,15]
Use or absence of use of chemical products as fertilizers:
The absence of 90 pesticides evaluated in the analyzed nopales confirmed that the producers do not apply agrochemicals in the crop. There was only one exception, Ometoate (0.031 ppm) was detected in a sample, but the amount detected was less than the limit allowed in horticultural products for export and national consumption, and it’s also not included among the prohibited pesticides or with restricted use (Agrolab, 2013) (COFEPRIS, 2004). Therefore, it can be concluded that the implementation of these measures to reduce the risks from biological, chemical and physical contaminants to protect the health of consumers has been successful for the production of O. ficus indica. [16,17,18]
The results obtained in this research on the properties of Opuntia ficus-indica show that its consumption prevents cardiovascular and diabetic diseases, since the presence of fiber, Cantina alkaloid and antioxidants, generally fortify human health. Also, when the requirements of natural origin, beneficial health effects, passing a toxicological test and no use of chemical products in its growth are met, it is how O. ficus is called as a nutraceutical food. From the previous point, a direct relationship between food - health is inferred. It is important that a new approach be given where the fundamental role that everything we eat can be recognized more easily. And what is this new approach? Nutraceutical foods.
The exposed diseases are part of the main causes of death worldwide, this fruit helps us reduce the risks of acquiring them. After the genetic factor, which is unappealable, we have our diet as a juncture. For the above reasons, food is the best medicine, and the Tuna is the perfect example for it.
Finally, the sustainable production of this fruit is made known: it optimizes the water it has available and avoids its waste, a habitat for microorganisms that promote soil fertility proliferates, thanks to the absence of agrochemicals it keeps the product in its natural state and prevents soil erosion. Finally, that’s why we say that the best medicine is food.
Thanks to biology and chemistry, in conjunction with other disciplines, it is how the approach between science and the phenomena that build our life could be brought about, it is through this research that it was possible to propose and establish solutions to the great problems that we face. There is a long way to go and many questions to answer, but with the interest and curiosity of young scientists, a great step will be marked.
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