Adding more oil to stir-fried carrots will help nutrients be better absorbed?

Carrots are a nutritious vegetable. The carotenoids they contain are very beneficial to the body. Many people who overuse their eyes know that they can protect their eyes by supplementing with lutein, which is a member of the large carotenoid family. However, there has always been such a piece of popular knowledge about carrots: since carotenoids can only be dissolved in oil, it is easier to absorb the nutrients when stir-frying than steaming them, and the more oil you use when cooking, the easier it is to absorb the carotenoids. In this way, carrots are really not a fuel-efficient lamp!

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01

Carotenoids have so many benefits for the human body!

What are the benefits of carotenoids to the human body that make housewives and cooks willingly spend oil to supplement their families?

1. Prevent a variety of chronic diseases. Because carotenoids have a good antioxidant effect, they can prevent cancer, cardiovascular disease, arteriosclerosis, cataracts and other diseases.

2. Promote embryo, growth and development and protect visual function. Vitamin A precursor substances represented by β-carotene can promote embryo, growth and development and protect visual function.

3. Protect eyesight. Lutein plays a major role here. Lutein can absorb a large amount of blue light close to ultraviolet light, thereby protecting the retina from light damage and preventing and improving eye diseases.

4. Enhance the body's immunity. Lycopene and beta-carotene have good immunomodulatory effects and can enhance the body's disease resistance.

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But it should be noted that eating foods rich in carotenoids does not mean that you have supplemented enough carotenoids. This is because they have an absorption rate problem. Only 2.6% of lutein in the food matrix can be absorbed and utilized, the proportion of lycopene is also 2.6%, and the proportion of beta-carotene is slightly higher, but only 3.5%. So, how can we supplement them to achieve the most ideal effect and let them shine for our health?

02

It is true that it can only be absorbed when mixed with lipids!

First we need to look at how carotenoids are absorbed.

During the processing, carotenoids in food are partially released from the food matrix due to heat, mechanical force or enzyme catalysis. After being ingested into the body, they are released again through chewing and the catalysis of salivary enzymes.

Due to the fat solubility of carotenoids, they must be mixed with lipids and encapsulated in lipid droplets. Carotenoids are then transferred out of the lipid droplets and converted into water-soluble mixed micelles in the small intestine together with bile salts, oils, and phospholipids. They then pass through the brush border membrane of the small intestinal epithelial cells and enter the cells to be utilized.

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Therefore, the type of fruit and vegetable, cooking method and food composition first affect the absorption and utilization of carotenoids. For example, the cells of fruits and vegetables such as carrots and bell peppers are larger, and the carotenoids in them are more easily released during processing and cooking; cooking methods such as cutting, beating, and steaming at home can destroy the integrity of fruit and vegetable cells and are more conducive to the release of carotenoids.

Eating foods rich in fats and oils such as cooking oil, salad, and egg yolks together with fruits and vegetables can increase the bioavailability of carotenoids by 20% to 200%. Therefore, adding an appropriate amount of fat during cooking can indeed improve the absorption and utilization of carotenoids.

03

Lipids are not limited to edible oils

There is also a limit to the degree of absorption

In this case, does it really mean that the more oil you put in, the better the carotenoids will be absorbed?

In fact, the oil added during the cooking process only makes it easier for carotenoids to be released from fruits and vegetables. In the small intestine, carotenoids must be transferred out of lipid droplets and converted into water-soluble mixed micelles together with bile salts, oils, and phospholipids before they can be absorbed.

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Therefore, the most important thing in the diet is to consume carotenoid-rich fruits and vegetables or health products together with other oil-containing foods, so that the carotenoids in the fruits and vegetables or those remaining in the intestinal cavity can form chylomicrons together with fat and be absorbed.

The intake of about 20 g of total fat (not just cooking oil, but also fat from other foods) per meal can significantly increase the absorption of carotenoids. For example, when cooking with meat, it should also be counted in the total amount of fat. Moreover, this absorption rate is also limited, and excessive intake will not increase the absorption. On the contrary, processing such as cutting, steaming, etc., which damages the tissues of fruits and vegetables and combines with the intake of oil, will greatly increase the absorption of carotenoids.

04

More than just carrots

These fruits and vegetables are also recommended

Carotenoids are not only found in carrots, but also in many vegetables and fruits: β-carotene mainly comes from dark green or red and yellow vegetables and fruits, such as carrots, broccoli, spinach, water spinach, sweet potatoes, etc.; lutein is more common in dark green leafy vegetables such as cabbage and spinach, as well as flowers such as marigolds and marigolds; and lycopene is more abundant in fruits and vegetables such as tomatoes, watermelons, pumpkins, mangoes, and papayas. Of course, remember to eat it with an appropriate amount of fat-containing foods, which is more conducive to absorption!

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Author: Zhang Zhongyuan Jiangsu Academy of Agricultural Sciences

Review | Sun Guiju, Director of the Department of Nutrition and Food Hygiene, School of Public Health, Southeast University

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