Top 15 Foods With Antioxidants: Why You Need Them And What Effect They Have

The function and effects of antioxidants are being talked about more and more. They are credited with anticancer activity, used to correct metabolic disorders and prevent premature aging.

What is the mechanism of action of these biologically active molecules? Is this the same magic pill that can be easily obtained along with food components? Let's figure it out.

Why do we need antioxidants

The final stage of obtaining energy takes place in the mitochondria: here, in our small cellular power plants, the respiratory chain is located - a system of enzymatic complexes that provides the pumping of protons and electrons and puts the final touch on the metabolic transformations of any organic substances. However, it is also a place where free radicals are normally formed - an inevitable by-product in the ATP factory. The imperfection of their structure (the absence of one or more electrons - in fact, “hands”, “legs” or even “heads”) causes their damaging effect: they, seeking to regain integrity, “take away” the missing electrons from normal cellular structures.

Perhaps the most striking demonstration of such vandalism, one way or another proceeding at the molecular level, is the peroxidation of lipids, the main (along with proteins) components of cell membranes, which will result in cell death.

However, in the process of evolution, our body has learned to use free radicals: it has turned them into a powerful defense factor against pathogens that invaded its borders. So, for example, immunocompetent cells - macrophages - after capturing and devouring bacteria, begin its digestion: this is an integral process of their work, necessary for further presentation on the surface of these cells of microbe-specific protein and polysaccharide particles that activate lymphocytes. And it is in the initial “killing” of foreign microorganisms that free radicals take part - reactive oxygen species and peroxide.

So, the body found a use even for these highly damaging compounds - it even connected them to the detoxification mechanisms that unfolded in hepatocytes. It remains to solve the last question: how to protect yourself: your macromolecules, vessel walls, and most importantly, genetic material? Recall that the latter is also contained in mitochondria - these are the only organelles that have their own (albeit very modest in comparison with nuclear) DNA molecules, damage to which is fraught with the development of a wide range of diseases - from oncology to neurodegenerative processes.

It should also be understood that despite the fact that the human body was still able to find a use for free radicals, the process of their formation actually remained uncontrolled. In particular, we are talking not so much about the enzymatic systems of immunocompetent cells (the same macrophage cleaners), but about the mitochondria themselves. And given that most of the processes occurring in the body require energy for their implementation (even the absorption of glucose in the intestine), the process of its formation is constant.

Since the control over the production of free radicals is too ephemeral, the regulation is carried out precisely by the neutralization system - antioxidants.

What is the effect of antioxidants

Antioxidants carry out their main task - the neutralization of free radicals - in various ways: some of them are enzymes that directly neutralize reactive oxygen species and peroxide. These include, in particular: catalase, peroxidase, superoxide dismutase.

The second group consists of non-enzymatic antioxidants: glutathione, vitamins (ascorbic acid, tocopherols) and their precursors (for example, beta-carotene), as well as flavonoids, anthocyanins and other biologically active substances.

In addition, it is assumed that they also prevent premature aging: the free radical theory of its development is still one of the leading ones. It is based on the hypothesis that structural changes in cells and tissues that occur over time in the body are due to the accumulation of macromolecules damaged by free radicals: proteins, lipids, DNA. This, according to scientists, in turn, is a mechanism that stops cell division: after all, if a defect in a particular structure is not only not corrected, but also inherited by daughter cells, this is fraught with atypism, which is actually equated with the onset of tumor development.

In addition, various signaling pathways are activated, resulting in the release of pro-inflammatory molecules. More and more new cells are involved in the pathological process.

Top 15 Foods High in Antioxidants

The catechins it contains exhibit a wide range of antioxidant activity. Epigallocatechin gallate, one of their main representatives, directly reduced liver damage in clinical studies, and also increased the level of glutathione - the main protector of our body and the main participant in the detoxification processes.

Polyphenolic compounds in this drink have anti-allergic, antibacterial, antiviral and protective action in relation to the cardiovascular system. The high consumption of green tea (according to statistics, about 120 ml per day) and the wide world production make it almost the only source of biologically active compounds of plant origin that a person receives daily.

However, along with numerous beneficial effects, with frequent use, there is also a risk of intoxication due to the toxic metals concentrated in it: cadmium, nickel and lead.

This widespread vegetable is often used in the cooking of most peoples of the world and is a low-calorie product with a high content of antioxidants - especially vitamin C and beta-carotene, from which (through biochemical transformations and under the condition of the normal functioning of the corresponding gene) retinol is formed.

By the way, it is one of the highest (among other foods) concentrations of ascorbic acid that makes pepper so popular - after all, only 50 grams is enough to more than cover the recommended daily intake of this vitamin, which plays a key role not only in the mechanisms of protecting cells from the army of free radicals , but also largely ensuring the formation of collagen fibers and maintaining its normal structure. The latter mediates the health of the entire cardiovascular system.

For a more visual example, we have provided a table below with the total antioxidant capacity (expressed in gallic acid equivalent) and the vitamin C content of some fruits and vegetables.

Berries are rich in flavonoids, phenolic compounds, vitamins, carotenoids and tannins - it is the high concentration of natural antioxidants that largely determines the wide range of their effects on the human body.

Numerous studies show their beneficial effects in the context of cancer therapy. In particular, they protect the genetic material of cells - DNA - from free radical damage due to the absorption of reactive oxygen species; inhibit the formation of metabolites with carcinogenic properties; affect various signaling pathways associated with cell division, their programmed death (apoptosis); the formation of new vessels - angiogenesis.

The berries also contain antioxidant enzymes: superoxide dismutase, catalase, ascorbate peroxidase, glutathione peroxidase and -reductase. This (along with the above effects) greatly contributes to maintaining the redox balance - at least in the berries themselves.

Unfortunately, scientists have not reached a consensus whether their antioxidant activity is manifested in mammals or whether it is inhibited in the gastrointestinal tract. At the moment, this question remains open, and so far the mechanisms of anti-cancer protection are being studied in isolation - that is, on human cell cultures in the laboratory. And there are already quite a few interesting results: for example, pre-treatment of freshly isolated lymphocytes with quercetin for 1 hour protects DNA from oxidative stress caused by peroxide.

Cruciferous vegetables are also effective in fighting certain types of cancer. They contain a large amount of phytochemicals, as well as vitamin A, riboflavin (B2), niacin (B3), ascorbic acid and some minerals and elements: iron, phosphorus and calcium.

Pomegranate has long been used in medicine of different peoples of the world. Its properties are already supported by a significant base of scientific studies demonstrating antioxidant, anti-inflammatory and even antitumor effects in various models.

It is the combination of different types of polyphenolic compounds (including catechins with tannins and anthocyanins) that makes it unique: it is active against several types of free radicals at once.

The antioxidant effects of its juice are many times greater than those of red wine and green tea, and fruit and peel extracts are able to selectively inhibit the growth of atypical prostate and lung cancer cells, while not having toxic effects on normal tissues and their structures.

The flower extract of this plant, especially rich in ellagic acid, when administered daily for seven days, significantly suppressed inflammatory processes in the large intestine, accompanied by oxidative stress. At the same time, the anti-ulcer effects provided were comparable to those that were carried out by typical drugs used to treat colitis - for example, sulfasalazine.

Another published study seems to be of no less interest to us: for example, 4-week use of pomegranate peel extract at a concentration of 6 mg/day in mice was associated with inhibition of the expression of inflammation markers in adipose tissue and in the large intestine, which once again emphasizes the pronounced antioxidant function.

Ellagic, gallic acids and urolithins contained in pomegranate are able to inhibit aromatase, an enzyme that converts androgens into estrogens. An excess of the latter is associated with the proliferation of breast cancer cells that are sensitive to this hormone.

Citrus flavonoids have long attracted the attention of scientists as potential components of various therapies. So, say, naringin, the concentration of which is quite high in some of their varieties, is able to correct the lipid spectrum of the blood, reducing the level of “bad” cholesterol in the composition of low-density lipoproteins, and also has anti-inflammatory, anti-carcinogenic and antioxidant effects. It not only neutralizes free forms of oxygen, but also directly reduces their production, and also restores the activity of mitochondrial enzymes.

It is believed that citrus flavonoids also have a neuroprotective function, modulating the activity of nerve cells, their plasticity, as well as influencing cognitive functions and mood.

For example, naringin, having anti-inflammatory activity, promotes the survival of dopaminergic neurons (during the synthesis of the neurotransmitter dopamine, a large amount of free radicals are formed that attack producer cells), which can potentially be used in the treatment of such a neurodegenerative disease as Parkinson's disease.

All these products have one thing in common: they contain the antioxidant resveratrol. This organic compound not only absorbs reactive oxygen species, thereby preventing the development of oxidative stress, but also has an anti-cancer effect, and is also actively discussed in the context of an anti-aging drug.

Resveratrol inhibits lipid peroxidation and increases the activity of protective enzymes such as superoxide dismutase and glutathione peroxidase in rat cardiomyocytes.

In mice, the introduction of resveratrol increased motor activity - this was carried out, according to the researchers, by increasing the number of functioning mitochondria.

Lack of Antioxidants

The lack of antioxidant systems causes the development of oxidative stress: an excess of free radicals in the absence of their neutralization leads to damage to cellular structures, and most importantly, to genetic material, becoming a trigger for a huge number of pathologies.

So, in diabetes mellitus (both types 1 and 2), oxidative stress leads to vascular complications, which plays a significant role in the development of myocardial infarction and atherosclerosis in the future. However, scientists still cannot decide: an excess of free radicals acts in this pathology as a concomitant phenomenon or a consequence of chronic hyperglycemia (elevated glucose levels in blood serum) - it is known that this largely distorts not only the activation of certain transcription factors, but also promotes the formation of end products of glycosylation - AGEs.

Premature aging, death of cells and their macromolecules, neurodegenerative processes and disorders of all types of metabolism are just a small list of pathologies that accompany a decrease in antioxidant activity. The latter may be the result of insufficient consumption of foods containing phenols and vitamins, or the result of the very violation of the transformation of these compounds already inside the body - we will talk about it in more detail below.

When antioxidants fail

Unfortunately, the intake of antioxidants (both in the form of supplements and in the form of food products) does not always bring the desired results: it is necessary, first of all, to take into account genetic factors and the characteristics of the metabolism of each individual organism.

For example, fat-soluble vitamins (which, recall, are capable of accumulation, which must be remembered when choosing a dosage and prescribing a course of their intake) in conditions of impaired bile outflow and formation, associated either with a decrease in the synthetic function of the liver, or with blockage of the corresponding ducts (with helminthic invasion , cholelithiasis), are not able to undergo enzymatic processing and further absorption on the epithelial villi of the intestine.

Pathology can also be from the side of the exocrine function of the pancreas: as you know, lipase, an enzyme that breaks down chemical bonds in lipid molecules, is the most sensitive, so its secretion, as a rule, is disturbed in the first place. In such cases, a complex work of a nutritionist with a gastroenterologist is necessary to identify the cause of the disease and prescribe the appropriate treatment with the selection of the right nutraceuticals and animal enzymes.

Genetics also plays an important role, especially in the context of the metabolic transformations of vitamins. For example, with a mutation in the BCMO1 gene, the product of which promotes the transition of beta-carotene, provitamin A of vegetables, to the active form (retinol), this process simply becomes impossible.

So, it is the knowledge of one's genetic characteristics that provides a clear understanding of what form and what vitamin must be taken for the normal functioning of the organs and systems of the body. Otherwise, you can use certain additives for years, but, apart from developing a certain sensitization, nothing can be achieved.

Antioxidant therapy will be ineffective without lifestyle changes - in particular, the elimination of stress factors that induce, in turn, the formation of free radicals and mediate mitochondrial dysfunction. It is also necessary to normalize the sleep pattern: departure to it should be no later than 23.00 - it is at this time that the peak of melatonin secretion is given. This hormone with pronounced antioxidant abilities is a direct antagonist of cortisol.

Reviewing nutrition, avoiding snacks and switching to a 3-day diet low in simple sugars is the key to a good carbohydrate metabolism. Violations of the latter (in particular, hyperglycemia) are a powerful trigger for oxidative stress.

Thus, significant results can be obtained only with an integrated approach that affects all areas of life.

The negative effect of antioxidants

Antioxidants (as well as any biologically active compounds) should be prescribed only after appropriate laboratory and / or instrumental diagnostic methods have been carried out and certain indications for their use have been identified. Of course, this applies to a greater extent to supplements and drugs: those compounds that are contained in food, in the process of enzymatic cleavage and exposure to certain conditions that have developed in the gastrointestinal tract, are not completely absorbed due to partial destruction.

Symptoms of hypo- and hypervitaminosis are often similar, which makes it somewhat difficult to differentiate them. Below we will list several signs that accompany an excessive intake of tocopherols and retinol in the body, and will try to demonstrate that sometimes antioxidants (when used incorrectly and / or not indicated) have significant side effects.

Too much vitamin A leads to:

• nausea;

• vomiting

• migraine;

• visual impairment;

• liver damage;

• alopecia;

• congenital malformations of the fetus.

Hypervitaminosis of tocopherols is associated with:

• nausea;

• diarrhea;

• bleeding.

In addition, it is necessary to take into account the effect of some antioxidants on microsomal liver enzymes that carry out the first phase of detoxification. So, say, grapefruit juice is able to suppress the work of CYP3A4 - a cytochrome that converts estrogens into a very proliferative 16-OH-estrone. On the other hand, curcumin inhibits the activity of CUS1A2, which metabolizes coffee and some drugs.