I bought a bunch of grapes today, they are crystal clear and mouth-watering.
When eating grapes, should you spit out the skins?
The tempting purple of grapes easily makes one think of a nutrient—anthocyanins. Anthocyanins are a type of flavonoid compound and one of the main pigments that form the colors of petals and fruits, mainly distributed in the epidermal cells and the hypodermis. They are widely found in the tissues of plants such as grapes, red cabbage, blueberries, eggplant skin, cherries, blood oranges, strawberries, mulberries, hawthorn skin, perilla, and black (red) rice.
While giving plants a beautiful outer layer, anthocyanins also play an important role as a powerful antioxidant, protecting the human body from damage by free radicals. They can enhance the elasticity of blood vessels, relax them, and increase systemic blood circulation, thereby having a certain blood pressure-lowering effect; they can boost the immune system, inhibit inflammation, and reduce allergies (I won't elaborate further on anthocyanins as many other articles have covered this topic).
In addition to anthocyanins, grape skins also contain another antioxidant: resveratrol. This component can reduce blood viscosity, inhibit platelet aggregation and vasodilation, prevent thrombus formation, and has preventive and therapeutic effects on coronary heart disease, ischemic heart disease, and hyperlipidemia. It can also prevent tumor formation, has estrogen-like effects, and can be used to treat diseases such as breast cancer.
A research report by Professor Sinclair of Harvard University, published in the journal *Nature*, pointed out that resveratrol may be the key to developing anti-aging and anti-cancer drugs. Research by Guangzhou University of Chinese Medicine has also confirmed that resveratrol can fight the AIDS virus.
Italian scientists fed a small fish native to Zimbabwe with different doses of resveratrol. The results showed that low-dose intake did not change the fish's lifespan, medium-dose resveratrol extended the fish's lifespan by one-third, and high-dose resveratrol extended the lifespan by more than 50%. Other studies have also found that resveratrol can significantly extend the lifespan of lower organisms. Resveratrol primarily exerts its anti-aging effect by protecting the DNA in cell mitochondria from damage, and we have reason to hope it can have the same effect in humans.
So, when we eat grapes, should we swallow the skins and seeds (the proanthocyanidin content in grape seeds is even higher) together to get the protection of these powerful antioxidants?
First, the current food safety situation is becoming increasingly unsatisfactory. I have grown a grape vine myself before and know that a large and frequent amount of pesticides is needed to grow grapes; without spraying, it's impossible to get any fruit. Grapes sold on the market are generally sprayed with a fungicide every 7-10 days from flowering and fruiting, and in the later stages, to prevent grape anthracnose from harming the fruit clusters, targeted and frequent spraying on the fruit clusters is necessary.
During the washing process, these pesticides cannot be completely removed. There are many fruit and vegetable washes on the market that claim to remove surface pesticides, but their actual effectiveness is not as good as advertised.
Second, the solubility of antioxidants such as proanthocyanidins and resveratrol in grapes in water is not high (resveratrol is even less soluble in water). Those who have studied nutrition know that nutrients must be soluble in water or fat to be absorbed by the human body. Low solubility means that most of the nutrients will "pass through the intestines" without achieving the desired effect.
Therefore, for the sake of your own health and safety, it's best to reluctantly forgo the rich nutrients in grape skins, such as fiber and poorly absorbed antioxidants. But don't worry, nature has given us another good beverage.
Although the aforementioned antioxidants have low solubility in water or are even insoluble, they are all easily soluble in organic solvents such as ethanol. Therefore, people often use a mixture of water and organic solvents to extract these components. Wine, made from grapes, becomes a natural polymer for these antioxidants (the antioxidants in wine are generally collectively called polyphenols, including gallic acid, catechin, quercetin, proanthocyanidins, salicylic acid, resveratrol, etc.). Research has found that the resveratrol content in wine is much higher than in grapes, and the content is higher in red wine than in white wine. The resveratrol content in domestic red wine ranges from 16.7 to 46.3 mg/L.
In the Mediterranean diet, the long-term habit of drinking red wine leads to a very low incidence of cardiovascular disease among locals. The results of the Lyon Diet Heart Study showed that compared to the group following the American Heart Association standard diet, the mortality rate from cardiovascular disease in the Mediterranean diet group was 76% lower. Of course, a reasonable overall diet structure is the premise for the above results, but red wine also plays an indispensable role.
However, everything needs to be in moderation. To borrow a slogan from an advertisement: red wine is good, but don't overindulge.