Several thousand molecules with a polyphenol structure (i.e., several hydroxyl groups on aromatic rings) have been identified in higher plants, and several hundred are found in edible plants. These molecules are secondary metabolites of plants and are generally involved in defending against ultraviolet radiation or aggression by pathogens. These compounds may be classified into different groups as a function of the number of phenol rings that they contain, and of the structural elements that bind these rings to one another. Distinctions are thus made between phenolic acids, flavonoids, stilbenes, and lignans. The flavonoids, which share a common structure consisting of two aromatic rings (A and B) that are bound together by three carbon atoms that form an oxygenated heterocycle (ring C), may themselves be divided into six subclasses as a function of the type of heterocycle involved: flavonols, flavones, isoflavones, flavanones, antho-cyanidins, and flavanols (catechins and proanthocyanidins). In addition to this diversity, polyphenols may be associated with various carbohydrates and organic acids, and with one another.
1. The Best Antioxidant-Rich Foods Make Up the Diet
1.1. Fresh, Organic Vegetables
Most edible vegetables, especially the green leafy ones, are loaded with potent phytochemicals, which are plant compounds that act as antioxidants. These phytochemicals can help reduce inflammation and eliminate carcinogens, protecting the body from a variety of health threats. However, to maximize the antioxidants in vegetables, they must be consumed raw, in a state closest to when they were harvested. Indeed, different types of heat treatment, such as boiling, baking, frying, or microwaving, can reduce the total antioxidant capacity of foods, affecting their ability to prevent lipid peroxidation 
. Juicing is highly recommended so as to absorb all the nutrients in the vegetables – it is one of the healthiest antioxidant drinks that can be added to the diet. The pulp can also be eaten instead of throwing it away. Sprouts are also powerful sources of antioxidants, minerals, vitamins, and enzymes that promote optimal health. In particular, those of broccoli and red cabbage have been found to contain much more vitamin C and other radical scavenging activities than mature vegetables, and they also appear to be more palatable to young people 
Recommendations: Overall, incorporating fresh, organic vegetables and sprouts into the diet can help boost antioxidant intake, reduce inflammation, and promote optimal health. Choosing the right preparation methods can also help maximize the overall antioxidant content of food, ensuring that the full range of benefits provided by these healthy foods is obtained 
Fruits are a great source of nutrients, including vitamins, minerals, and fiber. In addition, many fruits contain phytochemicals, which are plant-based compounds that can provide health benefits. Fresh berries such as blueberries, blackberries, cranberries, and raspberries are the best antioxidant fruits, as they contain powerful phytochemicals that directly inhibit the DNA binding of certain carcinogens 
. For example, anthocyanins, which are a type of flavonoid found in many berries, have been shown to inhibit the growth of cancer cells in laboratory studies 
. Other phytochemicals found in berries, such as ellagic acid and quercetin, have also been shown to have anticancer effects 
. Berries are also great sources of antioxidants such as vitamin C, carotenes, and carotenoids, as well as nutrients such as zinc, potassium, iron, calcium, and magnesium. Moreover, research has shown that daily consumption of antioxidant-rich fruits, such as berries, may help to improve various markers of cardiovascular health, including blood pressure, cholesterol levels, and endothelial function, leading to a significantly reduced risk of coronary heart disease 
. Other antioxidant-rich fruits include citrus fruits such as oranges and lemons, which are high in vitamin C and flavonoids 
. Apples, especially unpeeled, are also rich in antioxidants such as quercetin, catechin, and chlorogenic acid 
. Grapes, especially red and purple varieties, are also high in antioxidants, including resveratrol 
. In addition, fruits rich in potassium, such as bananas, cantaloupe, and avocados, have been associated with a reduced risk of cardiovascular disease 
. Potassium helps to regulate blood pressure by counteracting the effects of sodium on the body.
Recommendations: To increase your intake of antioxidants and phytochemicals, you should consume fresh berries regularly, as they have been shown to have anticancer and cardiovascular benefits. However, you should consume fruits in moderation, as they contain fructose, high amounts of which can be detrimental to health; this is true especially if too much fruit is consumed at dinner, since it strongly stimulates insulin production, especially in overweight people with insulin peripheral resistance or who are diabetic 
Pecans, walnuts, and hazelnuts are excellent antioxidant foods that can boost your heart health and overall health 
. Nuts are known to contain high levels of monounsaturated and polyunsaturated fats, fiber, minerals, vitamins, and various bioactive compounds that offer numerous health benefits. Research has shown that incorporating nuts into your diet may help lower the risk of coronary artery disease and hypertension. The possible ways in which nuts can help prevent these conditions include improving the lipid profile of the blood, reducing insulin resistance, and modulating inflammation, oxidative stress, and endothelial function 
Recommendations: Look for nuts that are organic and raw, not irradiated or pasteurized. Peanuts are usually less than ideal, as they are usually pesticide-laden and can be contaminated with a carcinogenic mold called aflatoxin 
1.4. Herbs and Spices
Aside from being an abundant source of antioxidants, these can have potential anti-cancer benefits. Herbs and spices differ mainly by source, as herbs typically come from the plant’s leaves while spices come from the bark, stem, and seeds. Both have been used for thousands of years to flavor foods and treat illnesses. Some of your best choices are ground cloves, ground cinnamon, oregano, turmeric, ginger, and garlic. For example, curcumin, the active ingredient in turmeric, has been shown to improve endothelial function and decrease inflammation, both of which are important in reducing the risk of cardiovascular disease and coronary artery disease. Studies have shown that curcumin can increase the activity of antioxidant enzymes, while also decreasing the levels of various oxidative stress markers and reactive oxygen species (ROS) 
. In addition to its antioxidant properties, curcumin has been found to have potent anti-inflammatory effects, which are also important for protecting the cardiovascular system. Chronic inflammation is a major risk factor for cardiovascular disease, and curcumin has been shown to inhibit the production of pro-inflammatory cytokines and other mediators of inflammation, such as NF-κB 
. Studies have also shown that curcumin can improve lipid profiles by reducing levels of total cholesterol, LDL cholesterol, and triglycerides, while increasing levels of HDL cholesterol 
. In addition, curcumin has been found to have antithrombotic effects, which may help prevent the formation of blood clots and reduce the risk of heart attacks and strokes 
. Similarly, research has suggested that ginger, another commonly used herb, may have cardioprotective properties, because it may help lower blood pressure, reduce inflammation, and improve lipid metabolism, all of which are important factors in preventing cardiovascular disease 
Recommendations: Ideally, you should only opt for fresh herbs and spices, as they are healthier and have higher antioxidant levels than processed, powdered versions. For example, the antioxidant activity of fresh garlic is 1.5 times higher than that of dry garlic powder 
. Moreover, adding fresh herbs and spices to your meals not only boosts their flavor and nutrition but can also help you reduce your intake of unhealthy additives. Processed and pre-packaged foods often contain high amounts of salt, sugar, and unhealthy fats to enhance their flavor, which can be detrimental to your health in the long run. By using fresh herbs and spices, you can avoid these additives and enjoy the natural flavors of your food. Finally, using herbs and spices to flavor your food can help you reduce your sodium intake, which is crucial for individuals with high blood pressure.
1.5. Organic Green Tea
This antioxidant-rich drink contains epigallocatechin-3-gallate (EGCG), a catechin polyphenol and one of the most powerful antioxidants known today. EGCG benefits you by lowering your risk of heart attack and stroke, glaucoma, high cholesterol, and more. Studies have also found that it can improve your exercise performance, increase fat oxidation, and even help prevent obesity due to its regulatory effect on fat metabolism 
. However, remember that not all green teas are created equal. Some processed green tea brands can contain very little or no EGCG at all. Some tea bags are also contaminated with fluoride or contain hazardous plastics that can leach into your tea when brewing.
Recommendations: To ensure you are drinking high-quality green tea, please buy only organic, loose-leaf tea from a reputable source. In addition, tea is not recommended for people that suffer from some forms of cardiac arrhythmias, as its alkaloid content can worsen such a problem, even if low-dose green tea intake has been related to a reduced incidence of both paroxysmal and persistent atrial fibrillation 
The importance of oxidative stress on endothelial function as a trigger for vessel damage and cardiovascular events has been established. In experimental animal models of atherosclerosis, hypercholesterolemia, hypertension, and diabetes, associations between oxidative stress and impaired endothelial function have been demonstrated. Among many biological changes that occur in the vessel wall under these conditions, reduced bioavailability of nitric oxide (NO) in a setting of increased superoxide anion levels seems to be a uniform underlying abnormality. Recent studies extended this potential mechanism to patients with coronary artery disease by demonstrating increased superoxide production of human blood vessels in association with endothelial vasomotor dysfunction and with clinical risk factors 
. Furthermore, endothelial dysfunction in patients with coronary artery disease or coronary risk factors could be reversed by the administration of agents capable of scavenging superoxide, such as vitamin C 
. These findings suggest that increased oxidative stress may be an important mechanism for impaired endothelial function in patients with atherosclerosis or cardiovascular risk factors.
Nowadays, there is growing interest in the role of dietary polyphenols in the prevention and treatment of heart diseases. Polyphenols have been shown to have a range of beneficial effects on cardiovascular health, including improving endothelial function, reducing inflammation, and lowering blood pressure. Several epidemiological studies have reported that high intake of dietary polyphenols is associated with a reduced risk of heart diseases, leading to a lower risk of coronary heart disease and a lower incidence of heart failure 
. Some studies have reported significant improvements in cardiovascular risk factors, such as blood pressure, cholesterol levels, and endothelial function, with supplementation of polyphenols 
. One of the most well-known examples of the potential health benefits of polyphenols is the French paradox, whereby moderate red wine consumption in a diet otherwise high in saturated fats is associated with a lower risk of cardiovascular mortality in French people from the Bordeaux region 
. Polyphenols can provide anti-fibrotic and myocardial protection by inhibiting oxidative stress and molecular pathways involved in heart fibrosis, and they can also promote vasodilation by increasing NO release, which improves vascular function by relaxing smooth muscle, inhibiting platelet aggregation, and increasing prostacyclin production. Moreover, polyphenols have been shown to have anti-diabetic effects by reducing blood glucose and glycated hemoglobin A1c levels, to be able to modulate liver function and lipid metabolism and to be effective in combating obesity. In fact, supplementation of polyphenols from red grapes leads down an anti-inflammatory pathway, causing weight reduction in obese individuals 
Overall, the evidence suggests that polyphenols have a beneficial impact on heart diseases (Figure 1).
2. Are Nutritional Supplements as Effective and Safe as Natural Food Sources?
Nutritional supplements are increasingly popular in the healthcare industry as people seek to augment their diets with vitamins, minerals, and other compounds thought to promote wellness and combat disease. Although these products can be effective in certain situations, they are often misused, overhyped, and even harmful to human health. While it is true that some dietary supplements can help meet nutrient needs, research suggests that they are often less effective than natural foods. Several studies suggest that dietary vitamin C is more protective than supplements and is associated with a reduced incidence of chronic diseases, including stroke, coronary heart disease, and various types of cancer 
. Similarly, recent studies found that supplementing with vitamin E did not lower the risk of heart disease, whereas consuming vitamin E through foods such as nuts and seeds did 
. Moreover, excessive intake of vitamin supplements can have harmful effects on the body, particularly when taken in high doses over long periods of time. For example, high doses of vitamin A can cause liver damage, while excessive intake of vitamin D can lead to hypercalcemia, a condition characterized by high levels of calcium in the blood. Therefore, even commonly used supplements, such as multivitamins, vitamin E, and folic acid, appear to have limited or no benefit, and some may be harmful 
The bioavailability of nutrients from whole foods is generally higher than that of supplements, and they also contain other compounds such as fiber, antioxidants, and phytochemicals that may have synergistic effects on health. There is also a concern that taking supplements may lead to a false sense of security and encourage unhealthy dietary practices. For example, some individuals may take supplements as a means of compensating for a poor diet, rather than making healthy dietary choices. Additionally, it is important to note that the dietary supplement industry is largely unregulated, and many products may not contain the ingredients listed on the label, or may be contaminated with harmful substances. For these reasons, it is generally best to obtain nutrients from whole foods rather than supplements.