Resveratrol: Health Benefits and Sources

Resveratrol is a naturally occurring polyphenol found in a range of plants, particularly in the skin of red grapes, blueberries, raspberries, mulberries, and peanuts. This compound belongs to the stilbenoid family, which plants produce as a defensive response to stress, injury, or pathogen attacks. Its presence in these foods is a testament to the plant's ability to protect itself from environmental threats.

Resveratrol has garnered significant attention in recent years due to its potential health benefits, particularly because of its antioxidant properties. As an antioxidant, resveratrol plays a crucial role in neutralizing free radicals—unstable molecules that can damage cells and contribute to aging and various diseases. Free radicals can lead to oxidative stress, which is linked to chronic inflammation and the development of serious health conditions like heart disease and cancer. By mitigating oxidative damage, resveratrol may help reduce inflammation and lower the risk of such diseases.

One of the most recognized sources of resveratrol is red wine. During the fermentation process, the grape skins, which are rich in resveratrol, are used, making red wine a notable source of this compound. This is one reason why red wine has often been associated with heart health benefits. However, resveratrol is also available in supplement form, which provides an alternative way to potentially gain its benefits without consuming alcohol.

Research into resveratrol's health benefits has revealed several promising effects. Studies suggest that it may improve cardiovascular health by reducing inflammation and preventing damage to blood vessels. Furthermore, resveratrol has shown potential neuroprotective effects, which could help in preserving memory and cognitive functions. Additionally, some studies have explored its role in weight management and blood sugar regulation, indicating that it may assist in weight loss and control blood sugar levels.

Despite these encouraging findings, it's important to note that more research is needed to fully understand the extent of resveratrol’s benefits and its effectiveness in humans. As with any supplement, consulting with a healthcare professional before adding resveratrol to your diet is advisable to ensure it aligns with your health needs and conditions.
Resveratrol: Health Benefits and Sources

Polyphenolic compound of lignans

The lignans are bioactive, non-nutrient, non-caloric phenolic plant compounds, with widespread occurrence in the plant kingdom, and which are ascribed a wide range of physiological functions, positively affecting human health. The lignans are a large group of phytochemicals that form the building blocks of plant cell walls.

Lignan precursors are found in a wide variety of plant-based foods, including seeds, whole grains, legumes, fruit, and vegetables. Among food sources rich in lignans, whole grains receive more attention because they are staple foods of the human diet globally and also contain essential vitamins, minerals, dietary fiber, β-glucan, inulin, numerous phytochemicals, phytosterols, phytin, and sphingolipids.

Regarding cereal grains, lignans are largely concentrated in their outer layers. In cereal grains, the highest lignan concentration is found in the fiber-rich outer layers (seed coat and pericarp), as well as the aleurone layer, whereas the lowest concentration is found in the inner endosperm

The lignan content of foods is generally low and usually does not exceed 2 mg/100 g. The exceptions are flaxseed27 (335 mg/100g) and sesame seeds (373 mg/100g), which have a lignan content a hundred times higher than other dietary sources.

The lignans are a class of phytoestrogen and can be metabolized to the biologically active enterolignans, enterodiol, and enterolactone by a consortium of intestinal bacteria.

The lignans consumed by animals and humans are hydrolyzed and metabolized to the biologically active enterolignans, enterodiol, and enterolactone by a consortium of intestinal bacteria.These metabolites possess a chemical structure similar to a sex hormone in the estrogen family and can act as phytoestrogens.

Phytoestrogens may have either estrogenic or antiestrogenic effects. Most available research links phytoestrogens to a variety of health benefits. The phytoestrogens can positively affect cognitive functions, such as learning, attention, and short-term memory, as well as influence sensorimotor such as fine touch, smell, hearing, and motor activities.

The scientific literature for lignan bioactive food components has shown a spectrum of important biological and health promoting activities such as cancer chemoprevention, antioxidant and antiinflammatory properties, lipid-lowering effects, cardiovascular disease (CVD) protection, and antimicrobial actions as well as obesity and diabetes management.

The plant lignans most commonly distributed in foods are lariciresinol, matairesinol, pinoresinol, and secoisolariciresinol. Several other lignans are present in some foods, including medioresinol (in sesame seeds, rye, and lemons), syringaresinol (in grains), sesamin and the lignan precursor sesamolin (in sesame seeds).
Polyphenolic compound of lignans

Ellagic acid –fruits and vegetables polyphenol

Ellagic acid is a molecule with a molecular weight of 302 gmol-1 . It is a molecule that is highly thermostable (melting point of 350°C).

Ellagic acid is a naturally occurring polyphenol found in some fruits and nuts including blackberries, raspberries, strawberries, cranberries, walnuts, pecans, pomegranates, wolfberry, and other plant foods, is one of the well-studied phytochemicals. It’s also in red wine, grape juice, and green tea.

In particular, berries provide ellagic acid in the form of ellagitannins, which constitute ∼60% (red raspberry) to 80% (cloudberry) of the total phenolic compounds present. There is emerging evidence that ellagic acid may decrease symptoms of chronic metabolic diseases, including dyslipidemia, insulin resistance, type 2 diabetes, and nonalcoholic fatty liver disease. Ellagic acid also possesses antioxidant, antimutagenic, and anticancer properties.

Ellagic acid reduces systolic blood pressure, through upregulating the endothelial nitric oxide synthase; this effect increases the bioavailability of nitric oxide, a decrease associated with endothelial dysfunction and an increase of blood pressure.

Due to a wide range of biological effects of ellagic acid, edible plants containing this phytochemical and its hydrolysable derivatives, mainly ellagitannins, are a valuable source of ellagic acid for humans and belong to functional foods that promote health and may reduce the risk of disease.
Ellagic acid –fruits and vegetables polyphenol

Nutrients in dark chocolate and health benefits

Many studies show that beneficial nutrients can be found in dark chocolate. Dark chocolate is made up of cocoa solids and sugar but no milk solids (prevalent in milk chocolate) and white chocolate, although referred to as chocolate had no cocoa solids, but instead is made of cocoa butter (the fat in chocolate), milk solids and sugar.

One of the nutrients in dark chocolate is called a polyphenol. Polyphenols are apart of a large family of natural compounds found in a wide variety of plant foods. They are helpful in assisting the human body protect itself from free radicals that cause oxidation.

Researchers believe that the benefits of dark chocolate are because of the flavonoids it contains, which are associated with the ability to lower the risk of heart disease and some cancers.

The heart may be vulnerable to damage by oxidation and flavonoids of dark chocolate hold potential for positive heart health effects.

Dark chocolate contains small amounts of B-complex vitamins (thiamin, or B1; riboflavin, or B2; niacin; vitamin B6’ and folate), needed for releasing energy and creating the body’s building blocks. Bone-enhancing vitamin D and antioxidant E are found in dark chocolate, which are important nutrients, too.

According to some studies done in Italy, dark chocolate has many of the same benefits as vitamin C helping the body use insulin more effectively and lower blood pressure. According to the study, participants who enjoyed 100 grams of dark chocolate daily for 15 days had reduced blood pressure and become more sensitive to insulin than they were prior to the "experiment".

Dark chocolate is plentiful in magnesium, important for brain functioning. It also boasts other nutrients, such a s copper, iron, manganese and zinc.
Nutrients in dark chocolate and health benefits

Phenolic compounds in chocolate

These polyphenols, mainly flavonoids with as catechin (flavan-3-ols), epicatechin and procyanidins, give chocolate antioxidant activity. Chocolate also contains additional flavonoids not found in tea, with high concentrations of oligomeric procyanidins.

Chocolates contain both a high quality and a high quantity of phenol antioxidants. Depending on the anthocyanin content, the pigmentation in polyphenol-storage cells ranges from white to deep purple.

Human studies have confirmed that polyphenols in chocolate are indeed bioavailable and able to increase the antioxidant capacity of plasma, with one study reporting that ingestion of 80 g of procyanidin rich-chocolate increased plasma epicatechin concentrations 12-fold.

Polyphenols and alkaloids, ~14 - 20% bean weight, are central to bean flavor character. Three groups of polyphenols can be differentiated: catechins or flvan-3-ols (~37%), anthocyanins (~4%) and proanthocyanidins (~58%).

Dark chocolate has the highest total catechin content, with approximately 53.5 mg/100 g, whereas milk chocolate contains approximately 15.9 mg/100 g. White chocolate primarily contains cocoa butter with minimal levels of polyphenols.
Phenolic compounds in chocolate

Phenolic compounds of punicalagin

Pomegranate is a rich source of many phenolic compounds including ellagitannins. Punicalagin is one of ellagitannins.

The potent antioxidant and anti-atherosclerotic activates of pomegranate juice are attributed to its polyphenol, including punicalagin, the major fruit ellagitannin and ellagic acid.

Punicalagin is the largest molecular weight and most abundant polyphenol known with a molecular weight of greater than 1000 has been reported to be responsible for over half of the juice’s potent antioxidant activity.

Punicalagin was shown to release ellagic acid in cell culture media, which actively induced apoptosis of colon cancer-derived Caco-2 cells.
Phenolic compounds of punicalagin

Ellagitannins in food

Plants with high concentrations of ellagitannins have been attributed to a variety of health benefits and they are important contributors to color, flavor and stability of many foods.

Strawberries, blackberries, cranberries walnuts, and pecans are particularly good source of the polyphenol compound ellagic acid that the hydrolysis product of ellagitannins.

Ellagitannins are polyphenol naturally occurring water-soluble tannins found in many plant foods (including grapes, raspberries, strawberries, blackberries, blueberries and some nuts) and in oak-aged red wines.

Anti-carcinogenicity of ellagitannins and their metabolite ellagic acid has been shown along with induction of apoptosis in some cancer cells.

Canning, pureeing, and freezing had little effect on ellagitannins, but processing berries into non-clarified and clarified juices resulted in total ellagitannin losses of 70 and 82% respectively, due to removal of ellagitannin rich seeds in the presscake.
Ellagitannins in food

Antioxidants in tea

Antioxidants are compounds that help the body to fight harmful free radicals. They accomplish this by circulating throughout the system and neutralizing unpaired electrons, rendering them inactive.

The free radicals occur naturally in the body but excess amount increases the risk of coronary attacks and cancer.

Tea is rich in polyphenolic compounds with antioxidant properties, mainly quercetin and catechin, and these compounds may inhibit oxidative damage to DNA, lipid, carbohydrate and protein.

Oxidative damage is associated with various chronic diseases, including cancer, coronary heart disease, cataract and dementia, and it has been suggested that consumption of tea may lower the risk of chronic disease by improving oxidative/antioxidant balance.

Black tea contains a significant amount of theaflavin compounds that make an important contribution to antioxidant activity, but their effectiveness varies with the individual theaflavin.

The domination of theaflavins are simple theaflavin, theaflavin-3-gallate, theaflavin-3’-gallate, theaflavin-3,3’-gallate which comprises 0.3% - 2% of the dry matter of black tea.

Green tea polyphenols are composed of numerous teas of catechin. Studies show that habitual green tea consumption causes in increase in plasma antioxidant status and a quantitative reduction of free radical-induced markers of lipid peroxidation. 
Antioxidants in tea

Polyphenols in tea

Tea is the most widely consumed beverage in the world after water. The daily consumption is around 3 billion cups per day.

Regular intake of tea is associated with improved antioxidant status in vivo, which may contribute to lowering the risk of coronary heart disease, stroke, and certain type of cancers.

The polyphenols in tea mainly include the following six groups of compounds: flavonols, hydroxy-4-flavonols, anthocyanins, flavones, flavonols, and phenolic acids.

Among these, the flavonols mainly catechins are most important and occupy 60-80% of the total amount of polyphenols in tea.

The tea plant is known to contain seven kinds of major catechins and traces of various other catechin derivatives.

These catechins are present in all part of the tea plant; 15-30% are present in the tea shoots, and there is also a high content in the second and third leaves.

About 90-95% of the flavonols undergo enzymatic oxidation to products which are closely responsible for the characteristics color of tea infusion and its taste.

During the manufacturing of tea, the content of polyphenols increases slightly at the beginning of withering but decreases right after.

Although the trend for the changes of polyphenols appears similar in different varieties the absolute content of polyphenols are different among them.
Polyphenols in tea