多食「生果同綠葉蔬菜」可以幫手減低糖尿病風險

2 days ago
7 min read

Increasing your intake of fruit and green leafy vegetables can lower the risk of diabetes.

This is the core message of Professor Kwak Jung‑hyun (Dept. of Food and Nutrition / Food Engineering, Inje University) in a recent health column.

According to the 2024 Diabetes Fact Sheet in Korea from the Korean Diabetes Association, 1 in 7 Korean adults aged 30 or above (14.8%) already has diabetes, and 4 in 10 (41.1%) are in a pre‑diabetic stage. More than half of people with diabetes also suffer from obesity, abdominal obesity, high blood pressure or high cholesterol, so proper blood‑sugar control is essential for a healthy life.

In February 2025, the Ministry of Food and Drug Safety released personalised nutrition guidelines for Korean adults in the pre‑diabetic stage. One recommendation that appears for almost every age group is to eat a generous and varied amount of fresh vegetables.

A large systematic review and meta‑analysis found that higher intakes of fruit or green leafy vegetables are associated with a lower risk of type 2 diabetes. Vegetables and fruit are rich in vitamins and minerals, have low energy density and relatively low glycaemic load. Their dietary fibre can improve insulin sensitivity and secretion, which helps reduce diabetes risk. In particular, green leafy vegetables provide vitamin C, phytochemicals and magnesium, all of which are believed to contribute to this protective effect. Fruit and vegetable intake can also beneficially change the gut microbiome. A cohort study in China reported that higher fruit intake improved gut microbial composition and metabolites, and this was linked to a lower risk of type 2 diabetes; in that study, cooked vegetables did not show the same effect, likely because long cooking weakened their impact on the microbiota.

The Korean Diabetes Association warns that eating too much fruit at once can cause a rapid spike in blood sugar, so they advise treating fruit as a separate snack or eating it together with a meal, and they generally recommend whole fruit over juice. Even so, a recent systematic review reported that 100% fruit juice has a neutral overall effect on glucose metabolism and diabetes risk—neither clearly beneficial nor clearly harmful—suggesting that moderate amounts of pure fruit juice do not necessarily impair blood‑sugar control.

One clinical study in 17 healthy adults compared blood‑sugar responses after eating 100 g of white bread with 250 mL of water, black tea or lemon juice. With lemon juice, the peak blood glucose was about 30% lower and occurred about 35 minutes later than with water. This may be because the acidity of lemon juice lowers the pH of the meal, reduces salivary amylase activity and slows starch digestion. Another small trial in 20 college students compared whole apples and blackberries with the same fruits in smoothie form; both forms produced similar glucose peaks, suggesting that smoothies do not automatically cause higher spikes. Of course, results can differ depending on the people studied, the type of fruit, how it is prepared, and how much and when it is consumed. In the same way, the impact of pressed juices depends strongly on which vegetables and fruits are used, in what amounts, and at what time they are consumed.

In Professor Kwak’s own study with 10 healthy adults, continuous glucose monitoring was used to examine blood‑sugar responses to different cold‑pressed juices. Each participant drank one 240 mL glass of:

Green CCA juice: 240 g celery, 30 g cabbage, 30 g apple
Green Light juice: 120 g celery, 90 g cabbage, 90 g kale, 20 g lemon

For both juices, blood glucose changes over 0–120 minutes were small. Interestingly, when 100 g of white bread was eaten with water or with the Green Light juice, blood sugar rose less when the bread was eaten together with the vegetable‑heavy juice.

This is likely because celery, kale and other green leafy vegetables are naturally low in sugar and can reduce the activity of salivary α‑amylase, slowing the breakdown of starch in bread into glucose. Even though insoluble fibre is removed in pressed juice, soluble fibre remains, which can slow carbohydrate absorption in the intestine and blunt the post‑meal glucose peak. Therefore, when you drink pressed juice, making it vegetable‑based with only modest amounts of fruit and pairing it with carbohydrate‑rich foods may actually support better blood‑sugar control.

Many studies have already shown that eating vegetables and fruit is beneficial for health. The key questions now are how much, in what combinations and in what form people with different health conditions should consume them; more research is still needed in this area.

In summary, for healthy blood‑sugar management:

Choose non‑starchy vegetables such as broccoli, spinach and lettuce as the main vegetables.
Eat plenty of leafy greens, root vegetables and cruciferous vegetables (for example, broccoli and cabbage); their fibre slows carbohydrate absorption and helps prevent sharp post‑meal spikes.
Eating vegetables before a meal can further help with glycaemic control.
For fruit, pick those with a lower glycaemic index, such as apples, pears, plums and oranges, rather than higher‑GI fruits like watermelon or grapes.

Especially in hot weather, when you crave a cold drink, it is wise to avoid sugar‑sweetened beverages and instead look for ways of using vegetables and fruit that support healthy blood‑sugar levels—and then put those habits into practice in daily life. Original in Korean: https://www.hani.co.kr/arti/hanihealth/healthcolumn/1209660.html

多食「生果同綠葉蔬菜」，可以幫手減低糖尿病風險。呢篇健康專欄就係由仁濟大學食品營養·食品工學系郭廷賢教授整理嘅重點。

根據大韓糖尿病學會 2024 年《韓國人糖尿病現況》資料，30 歲以上成年人當中，每 7 個就有 1 個（14.8%）係糖尿病患者，而且每 10 個入面有 4 個（41.1%）屬於糖尿病前期，比例好高。超過一半患者同時有肥胖、中央肥胖、高血壓、血脂異常等問題，所以要維持健康生活，穩定血糖控制係好關鍵。

2025 年 2 月，韓國食品藥品安全處為糖尿病前期成年人發佈咗「個人化營養指引」。當中幾乎所有年齡層（青年、中年、老年）都共同被強調嘅一點，就係：要持續攝取新鮮而且多樣化嘅蔬菜。

綜合多個大型研究嘅系統性文獻回顧同統合分析顯示，增加生果或綠葉蔬菜攝取量，可以降低第 2 型糖尿病嘅發病風險。原因係蔬菜同生果含有豐富維他命同礦物質，本身熱量密度同升糖負荷都較低，再加上當中的膳食纖維可以改善胰島素敏感度同分泌，從而有助預防糖尿病。特別係綠葉蔬菜裏面嘅維他命 C、植物性活性成分同鎂質，被認為對減低風險尤其重要。

另外，蔬菜同生果會影響腸道菌群，對血糖控制亦有幫助。有中國人群嘅隊列研究指出，多食生果可以令腸道細菌組成同代謝物出現正面變化，從而與第 2 型糖尿病風險下降有關；相反，嗰項研究入面嘅蔬菜（多數長時間煮熟）對糖尿病風險影響就唔明顯，可能因為高溫烹調削弱咗對腸道菌群嘅作用。

大韓糖尿病學會提醒，生果食得太多太急，容易令血糖急升，所以建議把生果當作獨立小食，或者跟正餐一齊食，同時一般建議以食原粒生果為主，而唔好用果汁代替。不過，最近有系統性回顧研究指出，適量飲用 100% 純果汁，對整體血糖代謝同糖尿病風險屬於「中性」影響——唔見得特別有益，但亦唔見得有害，暗示只要控制份量，純果汁未必一定損害血糖控制。

有一項臨床研究，找咗 17 位健康成年人，叫佢哋食 100 克白麵包，再分別配 250 毫升清水、紅茶或檸檬汁，量度血糖反應。結果發現，配檸檬汁嗰組，血糖峰值平均低咗大約 30%，而且出現血糖高峰嘅時間比飲水組遲咗約 35 分鐘。研究認為原因係檸檬汁降低咗食物嘅酸鹼值，抑制口水入面澱粉酶嘅活性，令澱粉消化變慢，血糖上升自然就冇咁急。另一項針對 20 位大學生嘅研究，將蘋果同黑莓分別用「原粒食」同「思慕雪」兩種方式比對，結果顯示兩種吃法嘅血糖高峰差別不大。當然，呢啲結果會受研究對象、果種類型、處理方法、時間同份量影響，唔可以簡單話所有人都一樣。對於冷壓果菜汁亦一樣——實際上對血糖嘅影響，很大程度取決於用咩蔬果、幾多份量、幾時飲。

郭教授亦親自做咗一個小型研究，找咗 10 位健康成年人，用連續血糖監測儀觀察唔同配方冷壓汁對血糖嘅影響。以 240 毫升一杯計算，配方包括：

「Green CCA」汁：西芹 240 克、椰菜 30 克、蘋果 30 克
「Green Light」汁：西芹 120 克、椰菜 90 克、羽衣甘藍 90 克、檸檬 20 克

結果顯示，兩款果菜汁喺 0–120 分鐘期間都只引起好細嘅血糖變化。更有趣嘅係，當受試者食 100 克白麵包配清水，或者配「Green Light」果菜汁時，比較血糖曲線，發現配蔬菜含量高嘅果菜汁一齊食，血糖反而升得更少。

推測原因係：西芹、羽衣甘藍等綠葉菜本身含糖量好低，又可以抑制唾液 α‑澱粉酶嘅活性，令麵包入面澱粉分解成葡萄糖嘅速度減慢。同時，即使冷壓過程除咗部分不溶性纖維，溶性膳食纖維仍然存在，可以喺腸道內拖慢糖分吸收，平滑血糖高峰。所以，如果用冷壓方式飲用果菜汁，以蔬菜為主、少量生果作點綴，尤其配合含澱粉嘅食物一齊食，對血糖管理反而可能有益。

總括而言，蔬菜同生果對健康有益，已經係公認事實。下一步要思考嘅係：對於唔同體質同疾病狀況嘅人，應該用咩比例、幾多份量、用咩形式去攝取，呢方面仍然需要更多研究。

實際建議如下：