The most weight-loss-enhancing fruit in autumn, I won’t let you not know!

Autumn is here. There is a kind of fruit with golden skin, fragrant grapefruit, and distinct flesh. When you take a bite, the sweet and sour juice fills your mouth. You can't stop eating it. That is grapefruit! How nutritious is grapefruit? Can people who are losing weight or have high blood sugar eat it safely? How to pick a delicious grapefruit? Let's talk about it in detail today.

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What is the relationship between pomelo, orange, tangerine and grapefruit?

The family relationships of citrus fruits are somewhat complex, and new varieties can emerge through mutual association.

1 grapefruit

Also known as pomelo, it belongs to the genus Citrus of the Rutaceae family. It has been cultivated in tropical Asia since ancient times and has a cultivation history of more than 3,000 years in my country. The fruit is large, with a diameter of about 25 cm or even wider.

2 sweet oranges

Perhaps it is a fruit that was created by hybridizing orange and pomelo in ancient times.[1] There are many varieties, such as navel orange, blood orange, sour orange, and bitter orange.

3. Grapefruit

Also known as grapefruit, it belongs to the genus Citrus in the Rutaceae family. Although the word "pomelo" is in its name, it is not a proper pomelo. It is a hybrid of pomelo and sweet orange. Compared with pomelo, grapefruit has a more obvious bitter taste, which mainly comes from the phenolic substances of naringin and limonin. [1]

4 The relationship between the four of them is

Pomelo and tangerine are both primitive species. Together they gave birth to sweet oranges, and together sweet oranges and pomeloes gave birth to grapefruits. In addition, grapefruits and tangerines can also give birth to tangelos. [1]

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How low in calories are grapefruits?

The most valuable thing about grapefruit is that it is not only delicious, but also helps lose weight! Beauty-conscious friends can eat it without any burden. The calorie content of grapefruit is 42kcal/100g, while the calorie content of grapefruit is lower, at 33~40kcal/100g. [2] Both grapefruit and grapefruit have lower calorie content than other autumn fruits such as kiwi, grape, winter jujube, pomegranate, and persimmon. A large grapefruit weighing more than 2 kilograms has an edible part of about 800 grams. If a person eats 1/4 of a grapefruit (about 200 grams), they will only consume about 80 kcal of calories, [2] which is not as much as a small banana; even if you eat half a grapefruit, you will consume about 160kcal of calories, which is equivalent to a large plate like the one in the picture below. If you want to replace it with winter jujube with the same calorie content, you can only eat 6. In comparison, grapefruit is still very satisfying and is very suitable for eating while watching TV series.

Image source: provided by the author

In addition, grapefruit contains nearly 90% water, which can enhance the feeling of fullness. Eating it as a snack in the morning and afternoon can help us control appetite, reduce the amount of food eaten at main meals, and is very helpful for weight loss.

How nutritious is grapefruit?

The nutritional value of pomelo is not bad. The vitamin C content of pomelo is 23mg/100g, [2] which is similar to lemon, but tastes better than lemon. The vitamin C content of grapefruit is 36~38mg/100g, which is slightly higher than that of orange. There are slight differences in the nutritional value of pomelo of different colors. There are three colors of pomelo: white flesh, red flesh, and yellow flesh. Someone compared the content of carotenoid components in three different flesh colors of pomelo: golden honey pomelo, red flesh honey pomelo, and Guanxi honey pomelo. The results showed that the main coloring components of golden honey pomelo juice are β-carotene, phytoene, α-carotene, β-cryptoxanthin and lycopene. The total amount of carotenoids is the highest, which is 2.6 times and 287.7 times that of red flesh honey pomelo and Guanxi honey pomelo respectively. [3]

Image source: Reference [3]

α-carotene, β-carotene, zeaxanthin and lutein are the main pigments that appear yellow, while lycopene is the main pigment that appears red. Therefore, the content of α-carotene, β-carotene and zeaxanthin in golden honey pomelo is the highest among the three; the content of lycopene in red honey pomelo is the highest among the three, which is 19.39 times that of golden honey pomelo. [3] Carotenoids are antioxidant ingredients that are beneficial to our health after ingestion. For example, β-carotene can be converted into vitamin A in the body, which is beneficial to the health of the eyes and skin; lycopene can help us fight inflammation and protect cardiovascular health.

Don’t throw away the grapefruit peel, eating it this way is nutritious and delicious

I spent a lot of money to buy a grapefruit, and nearly half of it was thick skin. It would be a pity to throw it away. It doesn't matter, the grapefruit skin can also be eaten, and it is quite nutritious.

Image source: provided by the author

Grapefruit peel contains a variety of nutrients, such as dietary fiber, polyphenols, flavonoids, etc. [4] Among them, dietary fiber can promote the proliferation of beneficial intestinal bacteria, promote gastrointestinal motility, prevent constipation, and stabilize blood sugar after meals. However, grapefruit peel may have a bitter taste. We can make it into grapefruit peel preserved fruit and grapefruit peel candy. The production process of grapefruit peel preserved fruit: grapefruit peel → wash → cut → pre-cook → boil with sugar (white sugar, honey) → candied → dried → finished product. The grapefruit peel preserved fruit is golden and transparent, with a prominent grapefruit flavor, no bitterness, full shape, and soft and elastic when chewed.

Image source: provided by the author

Production process of grapefruit peel candy: peel off the yellow outer skin → cut into pieces → add salt to soften → soak in water to wash off salt and bitterness → squeeze out water → change water to wash and soak → squeeze out water again → boil water → add grapefruit peel and cook for 1 minute → cool water → squeeze out water for later use → add yellow rock sugar, water, and a small amount of salt to the pot → turn to low heat to make flowing syrup after the rock sugar melts → add grapefruit peel and stir-fry on low heat → dry and harden → finished product, if you use red grapefruit peel, the color will be better. It should be noted that both methods contain added sugar, don't eat too much at a time, be careful of tooth decay and weight gain. If you are too lazy to use it to make food, you can put the grapefruit peel in the refrigerator. Grapefruit peel has a fresh fragrance, and putting it in the refrigerator can remove the odor.

Image source: provided by the author

Can people with diabetes eat grapefruit?

Since grapefruit is one of the most popular fruits in autumn, people with diabetes are naturally eager to try it. Grapefruit is actually quite friendly to people with diabetes. It is a fruit with a low glycemic index (low GI), with a GI value of only 25 [2]. It is also a fruit with a low glycemic load (low GL). Eating 100 grams of grapefruit has a GL of only 2.3. Even if you eat half a grapefruit (400 grams), the GL is only 9.2. GL < 10 means that it has little effect on blood sugar, so people with diabetes can eat it without worrying about it. According to the recommendations on fruit intake in the "Dietary Guidelines for Chinese Residents", you can eat 200 to 350 grams of fruit per day. If you plan to eat grapefruit as your fruit for the whole day, you don't have to worry about your blood sugar soaring if you stay within this recommended range.

When eating grapefruit, you must pay attention to this

If you are taking medication, it is best to be careful when eating grapefruit and other citrus fruits. Furanocoumarins and other chemical components contained in grapefruit have a significant inhibitory effect on CYP3A4 in the small intestinal mucosal epithelial cells, thereby affecting the effect of the drug or causing adverse reactions. [5]

Study 1 evaluated the effects of drinking 250 mL of grapefruit juice and pomegranate juice on the pharmacokinetics of dapoxetine in 12 healthy subjects for three consecutive days. It was found that grapefruit juice increased the bioavailability of dapoxetine, but reduced the clearance of dapoxetine by inhibiting intestinal and hepatic cytochrome CYP3A4. [6]

Study 2: 12 volunteers in China drank 250 ml of grapefruit juice every day for 7 consecutive days to explore its pharmacokinetic effects on the antidepressant blonanserin and its metabolite N-deethyl. It was found that grapefruit juice can increase the bioavailability of blonanserin and delay its clearance from the body. [7] There are also a large number of literature reports on the interaction between grapefruit and different drugs such as taladonna and lovastatin. The interaction relationship between more than 30 drugs and grapefruit has been confirmed. For example, antihypertensive drugs, lipid-lowering drugs, immunosuppressants, and a few tumor suppressor drugs, etc., read the instructions carefully or consult a doctor before taking the medicine. If you are really confused, just don't eat grapefruit during the period of taking the medicine.

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How to choose a delicious grapefruit?

Look at the variety: There are many varieties of pomelo on the market, and the edible rates vary. A study compared the differences between four varieties of pomelo: Crystal Honey Pomelo, Guanxi Honey Pomelo, Pomelo, and Ruby Pomelo. The edible rate of the whole fruit: Guanxi Honey Pomelo > Pomelo > Crystal Honey Pomelo > Ruby Pomelo. Guanxi Honey Pomelo has the lowest percentage of skin weight per fruit and the highest edible rate. Crystal Honey Pomelo and Pomelo have fewer seeds, with only 1 to 3 seeds per fruit. Guanxi Honey Pomelo is second, and Ruby Pomelo has the most seeds, with an average of 108 seeds per fruit. In terms of taste, Pomelo has the lowest sweetness, the highest acidity, and the strongest bitterness, but the richest juice content. Guanxi Honey Pomelo has the highest sweetness. Crystal Honey Pomelo has the richest flavor, tender fruit, moderate sweetness and sourness, and the best overall taste. In terms of single fruit weight, grapefruit has the smallest. [8]

So, in general, if you want to buy a sweet and big pomelo, choose Crystal Honey Pomelo or Guanxi Honey Pomelo; if you like small and sour ones, buy grapefruit.

Look at the appearance: choose fruits with regular shape and no deformities, smooth skin and dark color, which are more mature and less bitter.

Smell: Ripe grapefruit has a rich and aromatic smell.

Weigh the weight: choose the heavier ones over the lighter ones. For grapefruits of similar size, choose the heavier ones, which means they have more water content, are fresher, and are juicier and more delicious. Large but light grapefruits may have their capsules burst, and their flesh may be dry and tasteless.

Press the skin: Gently press the skin to see if there is a dent and whether the skin is elastic. If the dent is large and the elasticity is poor, it means the quality is poor.

In the list of must-eat fruits in autumn, pomelo must be on the list. Moreover, the word "柚" in pomelo is homophonic with the word "佑" in "佑" (protection), so pomelo is also called "佑子" (protection child), and is often regarded as an auspicious fruit. Hurry up and arrange a big pomelo for your family, so that you can share it together!

References

[1] Harold Mackey, Food and Cooking: Vegetables, Fruits, Spices, and Grains. Translated by Cai Chengzhi. Beijing Fine Arts Photography Publishing House. August 2013.

[2] Yang Yuexin. Chinese Food Composition Table 6th Edition Volume 1[M]. Peking University Medical Press, 2018

[3] Lu Xinkun, Lin Qihua, Lu Xiumin, et al. Comparison of carotenoid composition and content in different pomelo pulp colors [J]. Journal of Fujian Agricultural Sciences, 2012, 27(07): 723-727.

[4] Qi Qiqiong, Wei Qianni, Guo Fengjun, et al. Research progress on comprehensive utilization of active ingredients from grapefruit peel[J]. Modern Food, 2021(22):97-99.

[5] Bailey, DDG, Dresser, GKInteractions Between Grapefruit Juice and Cardiovascular Drugs. Am J Cordiovosc Drugs 4, 281–297 (2004).

[6] Ahmed M, Donia F, Elbarbry K. Effects of Grapefruit and Pomegranate Juices on the Pharmacokinetic Properties of Dapoxetine and Midazolam in Healthy Subjects[J]. Eur J Drug Metab Ph, 2017, 42(3): 397-405.

[7]Shang DW, Wang Zz, Hu HT, et al. Effects of food and grapefruit juice on single-dose pharmacokinetics ofblonanserin in healthy Chinese subiects[J]. Eur J Clin Pharmacol, 2018, 74 (1): 61-67.

[8] Zhou Xianyan, Zhu Chunhua, Gao Junyan, et al. Study on the quality differences of different grapefruit varieties and different parts of the fruit[J]. Journal of Tropical Crops, 2018, 39(12): 2396-2403.

Author: Xue Qingxin, member of Chinese Nutrition Society, registered nutritionist, health manager, public nutritionist

Review | Ruan Guangfeng, Deputy Director of Kexin Food and Health Information Exchange Center