《美國飲食指南》是每五年更新一次以美國人健康為出發點的飲食指南，因其科學影響力而長年受到全球關注與參考。2025–2030 年最新版的指南轉向明顯，科學重點不再只放在生理數值如膽固醇（Cholesterol）或低密度脂蛋白（Low-density lipoprotein, LDL）等數據上，而是更重視飲食是否真正影響慢性病風險與整體健康結果。這轉變反映在整體飲食結構上，指南提出着重增加蛋白質攝取、下調全穀類與整體碳水化合物比重。而食物選擇亦強調以蔬菜、優質蛋白質與少加工的「真食物」為主。
由量到質 碳水角色重新定義
過往建議成人需每日攝取約 6–11 份全穀類為主要熱量來源；新指南則調整為每日約 2–4 份，並應依個人熱量需求、活動量與代謝健康狀況彈性安排。新指南亦強調碳水化合物的「品質」，比單純攝取量更關鍵。富含膳食纖維的全穀類（如燕麥、糙米及全麥等）仍是重要的纖維與微量營養素來源，但不再是餐食中份量最多的「基礎」；相反，白麵包、餅乾等高度加工的精製碳水化合物則建議需大幅減少。
多項研究分析亦顯示，相較於高碳水或傳統低脂飲食，低碳水飲食在改善糖化血色素（Glycated hemoglobin, HbA1c）、空腹血糖、三酸甘油脂（Triglycerides）與體重控制方面都較有效。一項中國研究追蹤超過 11 萬名中老年成人平均9.8年，顯示長期高比例攝取精製碳水化合物與冠心病風險上升有關；而下調碳水比例並以蛋白質與脂肪取代部分熱量，卻並未增加心血管風險。
低脂不再唯一 脂肪重新定位
過去數十年，低脂飲食一直被視為保護心血管健康的方法之一。然而最新版指南已不再將低脂視為唯一正確選擇。在不額外添加糖的前提下，全脂乳製品現時出現在「可以吃」名單中，反映指南對天然食物中的脂肪重新評價。近十多年的系統性回顧與追蹤研究均顯示，單純提高或降低飽和脂肪（Saturated fat）攝取，並未一致影響心肌梗塞、中風或心血管死亡率等臨床風險。
進一步的研究分析指出，若以精製碳水化合物取代飽和脂肪，並未帶來心血管好處；若改以多元不飽和脂肪（Polyunsaturated fatty acids, PUFA）或單元不飽和脂肪（Monounsaturated fatty acids, MUFA）替代，部分研究則顯示心血管事件風險下降。然而，研究對反式脂肪（Trans fat）的危害證據相當一致，它與心血管疾病與總死亡率明確相關。因此新版指南重點由限制飽和脂肪，轉向避免反式脂肪與減少超加工食品。
指南亦提醒脂肪在烹調時的穩定性。富含 PUFA 的植物油在高溫下較易氧化。相對而言，橄欖油與飽和脂肪比例較高的油脂在高溫烹調時較為穩定，有助降低氧化風險。因此指南以原形食物與適當用油為整體方向。
有研究綜合多項臨床試驗，直接比較低碳水與低脂飲食，結果顯示低脂飲食在體重控制上的效果相對有限。相較之下，低碳水飲食在降低腰圍、體重與代謝症綜合症發病率方面表現較佳。在減少精製碳水的前提下，保留來自天然食物的脂肪（包括飽和脂肪），往往更有助維持飽足感及食欲，這也是新版指南不再設定明確飽和脂肪上限的重要原因。
飲食更多蛋白質 支援代謝與肌肉
過去指南建議蛋白質每日攝取量約為每公斤體重 0.8 克；新指南則上調至約 1.2–1.6 克，並強調依年齡、活動量與健康狀況調整。以 70 公斤成年人為例，每日建議量由約 56 克提高至 84–112 克。
來自美國與歐洲的臨床試驗與統合分析顯示，在減重或熱量受限情境中，較高蛋白質攝取有助保留瘦體重（Lean mass）、減少肌肉流失，並提升飽足感與食慾。多項統合分析顯示，對腎功能正常的人士而言，每日蛋白質攝取約為每公斤體重 1.2–2.0 克，並不影響腎功能指標，亦未增加腎臟疾病風險。但已有腎臟疾病者，仍應在醫生指導下調整飲食。另有不少研究指出，蛋白質轉化為肌肉的關鍵在於是否搭配身體活動。在配合阻力運動的情況下，每日約 1.2–2.0 克／公斤體重的蛋白質攝取，有助促進肌肉蛋白合成，支持肌肉量與功能維持。因肌肉量影響新陳代謝率，因此減重人士尢其需注意蛋白質攝取。
無論是調整碳水、重新定位脂肪，或提高蛋白質比例，腸道健康始終是整體飲食建議的重要基礎。指南指出，超加工食品容易干擾腸道菌平衡；而蔬菜、水果、豆類、堅果、種子及發酵食品等能提供膳食纖維／益生元的食品，有助維持多樣而穩定的腸道微生物群。健康平衡的腸道微生物群，與較佳的消化功能、免疫健康與代謝狀態密切相關。
對香港人而言，這份指南同樣具有高度參考價值。在外食頻繁、生活節奏急速的環境下，透過提高蛋白質、減少精製碳水化合物、選擇原形的食物並重視腸道健康，有助改善代謝健康，並降低肥胖與慢性疾病的風險。
美國飲食指南, 2025–2030 飲食指南, 碳水減蛋白增, 低碳水飲食, 健康飲食指引, 脂肪重新定位, 飽和脂肪, 反式脂肪, 蛋白質攝取, 代謝健康, 體重管理, 腸道微生物群, 真食物, 香港飲食健康
Dietary Guidelines for Americans, 2025–2030 Dietary Guidelines, low carbohydrate diet, higher protein intake, healthy eating guidelines, dietary fat quality, saturated fat, trans fat, protein intake, metabolic health, weight management, gut microbiome, whole foods, public health nutrition
參考資料/延伸閱讀:
＜益生第一關＞2026/01/14--『三高不是三種病 而是代謝失衡的警號』
https://hskgene.com/blogs/probiofirst/mets
＜益生第一關＞2026/01/07--『重新讀懂血脂 真正評估心血管風險』
https://hskgene.com/blogs/probiofirst/tg_ldl
＜益生第一關＞2019/07/12--『低碳減肥之迷思』
https://hskgene.com/blogs/probiofirst/lowcarbs?_pos=3&_sid=72e949718&_ss=r
＜益生第一關＞2025/08/27--『週末運動有效果 蛋白質益生菌再補足』
https://hskgene.com/blogs/probiofirst/weekend_warriors?_pos=30&_sid=263d1184e&_ss=r
＜益生第一關＞2026/02/26--『營養烹調選對油 美味健康勝一籌』
https://hskgene.com/blogs/probiofirst/oil-cooking?_pos=3&_sid=1d4df03d3&_ss=r
Easy Reading:
The Dietary Guidelines for Americans reset U.S. nutrition policy by restoring science, common sense, and real food as the foundation of national health.| U.S. Department of Agriculture and U.S. Department of Health and Human Services| 01-2026
https://realfood.gov/#resources
美國新食物金字塔掀熱議 衞生署指現行指引參考世衛 營養師指傳統指引過時︱Yahoo| 14-01-2026
美國最新飲食指南倒金字塔出爐！全脂奶、紅肉大翻身？醫生拆解7大顛覆位：牛油大平反 | U Food | 12-01-2026
Google Images:
美國飲食指南 2026 Dietary Guidelines for Americans 2026
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