Vegetables or vegetable juice?Is there a big advantage or a disadvantage?
From a health point of view, we recommend that one person eat 400-500 grams of fresh vegetables a day. However, many people currently do not have enough vegetables, and some are even less than half of the recommended amount, especially when eating out often, not eating dinner, People who are dieting to lose weight as well as men.
Vegetables or vegetable juice?
With the popularity of wall-breaking machines, vegetable juice was once a very popular healthy way to eat. Wash and cut all kinds of vegetables, add fresh fruit or milk, and put them directly into the wall-breaking machine to rotate at high speed for 2 minutes. Not only is it convenient to make, but also the vegetables are rich in variety and full of nutrition. It is sought after by some people in terms of whitening, spotting, detoxification, weight loss, and anti-aging.
At the same time, the nutritional value and safety of vegetable juice have also been strongly questioned. Opponents pointed out that after squeezing vegetable juice, it will not only lose a large amount of dietary fiber and vitamin C, but also introduce additional sugars, but will also affect the body due to the intake of large amounts of oxalic acid, plant lectins, isothiocyanates and other anti-nutritional ingredients. Cause damage.
In this way, in daily life, can we still substitute vegetable juice for fresh vegetables? For health, is it a disadvantage or a benefit?
Is vegetable juice nutritious?
Obvious loss of dietary fiber in vegetable juice
For vegetable juice made with a juicer or commercially available vegetable juice, part of the dietary fiber will be lost as the vegetable residue is filtered out.
The average dietary fiber content in fresh vegetables and fruits is about 2%. From the nutritional composition table of commercially available fruit juices, it can be seen that the dietary fiber in fruit juices is only about 1%. Compared with fresh fruits and vegetables, the dietary fiber loss is half. .
Juicing of vegetables leads to significant loss of vitamins
Vegetable juice squeezing can cause a lot of vitamin loss, especially VC. This is because oxidation occurs during the juice extraction process, resulting in the loss of vitamins. Of course, in conventional cooking, some vitamins are lost due to heating. For VC, both of these are extremely destructive.
For example, if vegetables rich in VC such as peas, green beans and okra are boiled for 5 minutes and then simmered for 30 minutes, the VC loss is 25.2%, 18.2%, and 21.6%, respectively. In the process of kiwi juice, after coarse filtration and centrifugal clarification, the loss rate of vitamin C is about 24.4%-27.9%. In addition, conventional cooking also has a certain loss of other vitamins. According to reports, vegetable boiling may cause a loss of 67% of vitamin A, a loss of 60% of folic acid, and a loss of 20%-80% of vitamin B1.
From this point of view, in terms of vitamins, vegetable juice will also lose part of the vitamin.
The content of functional ingredients such as polyphenols is higher after vegetable juice is squeezed
Since many nutrients in vegetables are thermally unstable (not resistant to high temperatures), the commonly used methods such as boiling, microwave, and stir-frying will cause the loss of some nutrients that are not resistant to high temperatures.
In 2008, the Hong Kong Polytechnic University compared several commonly used methods to compare the polyphenol content in brassica vegetables (broccoli, cauliflower, Chinese cabbage, cabbage), and found that the four kinds of vegetables directly squeeze the juice, and the polyphenol content is high. For several other cooking methods.
Health effects of vegetable juice
It can be seen from the above that compared with conventional cooking, apart from the obvious loss of dietary fiber by removing slag and squeezing juice, vegetable juice does not have much disadvantage in terms of nutrients, but may enrich some functional ingredients. What about its health effects in disease prevention? Let’s take a look at some scientific research
(1) Vegetable juice has a certain preventive effect on cardiovascular diseases
Drinking vegetable juice, especially mixed vegetable juice, has a good effect on promoting cardiovascular health and preventing cardiovascular diseases such as hyperlipidemia, hypertension, hyperemia, coronary heart disease.
In 2017, the nutritional journal Nutrients published a randomized controlled clinical study. The results showed that daily consumption of concentrated fruit and vegetable juices can improve metabolism by reducing systemic inflammation and blood lipid levels in overweight and obese people, thereby reducing chronic obesity caused by obesity. Disease risk. For some people who have certain body inflammation, this health effect is even more obvious.
In fact, as early as 2006, “Int J Food Sci Nutr.” published a review analysis of the effect of vegetable juice on cancer and cardiovascular disease prevention. Based on the results of academic research at the time, the author analyzed whether the prevention of diseases such as cancer and cardiovascular disease by vegetables depends on the dietary fiber in vegetables, and whether vegetable juice alone has a disease prevention effect.
The results show that vegetable juice has the effect of lowering blood pressure and improving blood lipids. Its preventive effect on cardiovascular diseases and other chronic diseases depends more on the antioxidants and other nutrients in vegetables than dietary fiber. Simply drinking 100% vegetable juice still has the effect of reducing the risk of cardiovascular disease.
In 2017, the Hua-Bin Li team of Sun Yat-sen University conducted a review and analysis of the mechanism of vegetable juice in preventing cardiovascular diseases, and concluded that the prevention of cardiovascular diseases and other chronic diseases by vegetable juice is mainly based on antioxidant effects, improving the cardiovascular system, and inhibiting platelets. Aggregation, anti-inflammatory and prevention of hyperhomocysteinemia.
(2) Vegetable juice has no effect on cancer prevention
Although vegetable juice contains a large amount of antioxidant components, it has obvious effects on preventing and repairing cell DNA damage, so theoretically, it still has a certain preventive effect on cancer. However, the current clinical research results are that vegetable juice has no preventive or ameliorating effect on cancer.
Whole tomatoes have a good preventive effect on prostate cancer, but tomato juice no longer has this preventive effect. Some studies have even found that drinking fruit and vegetable juice has a slight promoting effect on kidney cancer.
It can be seen that from the perspective of nutritional value and health effects, vegetable juice is a healthy food worthy of promotion. For some people who have insufficient intake of vegetables for three meals, drinking vegetable juice appropriately between meals can help increase the whole day. Your vegetable intake enhances nutrition.
So can we safely substitute vegetable juice for vegetables? actually not. The safety risk that vegetable juice may bring is the issue that we should be more concerned about.
Is vegetable juice safe?
Since vegetable juices are almost always raw vegetables and fruits that are cleaned and directly squeezed out, the anti-nutrient components in the vegetables cannot be removed, and will remain and be enriched in the vegetable juice. Regular drinking does bring greater safety risks.
- Anti-nutritional factors and toxic substances
There are a lot of anti-nutritional factors or toxic components in vegetables, mainly oxalic acid, tannins, lectins, furanocoumarins, etc. Generally speaking, heating or boiling can remove most of the toxins, so we don’t eat vegetables normally. There will be physical discomfort.
However, because vegetable juice is directly squeezed and drunk from raw vegetables, these bad ingredients will all dissolve in the juice and cause physical damage. It has been reported that a lot of continuous drinking of vegetable juice rich in oxalic acid causes kidney stones.
In addition, the dietary fiber, oxalic acid and other components in plants will also affect the absorption of calcium, iron, zinc and other minerals. These are the nutrients that we Chinese are more likely to lack. Therefore, it is not advisable to drink vegetable juice at the same time as rich in these nutrients. Eat the food together to avoid affecting the absorption of minerals.
- Pesticide residues
Pesticide residues in vegetables have always been an important issue of food safety. Often, the better-looking, the more high-quality vegetables that meet the requirements of supermarket industrialization, the higher the probability that the pesticide residues will exceed the standard. Especially in summer when pests are active, the dosage and residues of pesticides need to be paid more attention.
Our regular short-time cleaning, in fact, cannot completely clean the pesticide residues. During conventional cooking, the pesticide residues will be decomposed at high temperature and further eliminated. For vegetable juices, the risk of pesticide residues is greater due to the lack of subsequent high-temperature cooking. Especially for children who are growing and developing, exposure to organic phosphorus and other pesticides has certain effects on their IQ, social adaptability and physical growth.
- Microbial contamination
Some viruses and pathogenic bacteria may adhere to the surface of fresh vegetables. Studies have shown that lettuce contaminated with coronavirus BCoV-88 is kept in a refrigerator at 4°C, and the pathogenic activity of the virus can be maintained for more than 14 days, but washing with water cannot completely remove it.
Therefore, if you squeeze the juice directly after washing the vegetables, the risk of infection with pathogenic bacteria or viruses will be greatly increased. The summer is hot and the probability of diarrhea increases, which is also related to the increase in the frequency of people eating cold dishes.
- Be wary of the addition of extra sugar and flavor
The taste of pure vegetable juice is difficult to accept, so when squeezing the juice, you need to add sugar such as honey/white sugar, or you need to squeeze the juice with the sweetness of the fruit. The more delicious the vegetable juice, the higher the sugar content.
The vegetable itself is a low-sugar and low-carb water ingredient. After adding sugar or fruit, it becomes a cup of sugar water. The content of carbohydrate (mainly sugar) in commercially available vegetable juices is generally above 10%.
In addition to sugar, in order to increase the flavor, commercially available vegetable juices often add flavors. For developing children, too much flavor can easily affect the children’s sense of taste, causing them to be picky and partial.
How to seek advantages and avoid disadvantages and drink vegetable juice healthily?
In summary, vegetable juice has certain health and nutritional value, and can be used as a temporary supplement when the three meals are insufficient. It is not recommended to completely replace whole vegetables.
For people who want to drink vegetable juice, what are the ways to avoid safety risks and other precautions?
- Choose a wall breaker
Traditional juice extraction will remove a large amount of vegetable residues, resulting in the loss of dietary fiber. So how can it be avoided? The wall breaking machine that has become popular in recent years has actually solved this problem very well. As long as we keep the food residue and crush it to a suitable particle size with a wall breaker, we can avoid the loss of dietary fiber while having an acceptable taste.
- Juice after blanching
Vegetable blanching can not only remove most of the oxalic acid, but also remove microorganisms on the surface and remove certain pesticide residues, which greatly improves the safety. In addition, squeezing the juice after blanching for a short time can also reduce the loss of vitamins caused by oxidation.
- This seasoning is healthier
Compared with added sugar, such as honey, white sugar, etc., it is healthier to use fresh fruits and vegetables to taste. For the sugar problem caused by the addition of fruits, you only need to subtract the amount of fruit added in the fruit juice from the daily fruit consumption (about half a catty).
What should I do if the fruit juice is high in sugar, fast in digestion, and fast in blood sugar? Most of the fruits and vegetables are low GI foods, the cell structure is destroyed after the juice is extracted, and the sugar production speed is greatly increased. The addition of milk when squeezing the juice can reduce the sugar production speed very well. Such a cup of milkshake, compared with pure vegetable juice, also increases the nutrient density, is it just a few birds with one stone?
- Replace occasionally, not to rely on
Drinking vegetable juice cannot reduce the consumption of whole vegetables in the three meals. As a snack between meals, drinking a glass of vegetable juice and adding milk and nuts can increase the intake of vegetables while enriching the entire diet. It is also a stepping stone for people who do not have the habit of eating healthy foods such as nuts and fruits. A way to a healthy life.
In addition, vegetable juice can only be used as an alternative to our lack of daily vegetable intake. It is still recommended to use whole fruits and vegetables as the mainstay in daily life. It is not advisable to use vegetable juice as a substitute for vegetables, otherwise it will lose part of the health effects of vegetables.
At present, there are not many varieties of vegetable juice. Compared with eating a variety of whole vegetables, if you only drink a few vegetable juices for a long time, it is difficult for the human body to obtain sufficient and comprehensive nutrients.
Moreover, once the vegetable juice is improperly prepared, there are still certain safety risks and more nutrient loss risks. The addition of sugar to improve the taste may increase energy and fluctuate blood sugar, which is harmful to health.