雅思阅读 97: The Egg That Disagrees With You（和你过不去的那颗鸡蛋）

改编自 PMC / Frontiers in Microbiology（2020–2026年）。雅思阅读 Section 3 难度，约 1050 词。 素材来源：https://pmc.ncbi.nlm.nih.gov/articles/PMC7527138/

Reading Passage

A. For generations, dietary advice has been stubbornly democratic. The same plate diagram, the same pyramid, the same handful of "healthy" foods was recommended to everyone, on the assumption that a carrot or a slice of bread affects all bodies in roughly the same way. The calorie, that cheerful unit invented to make food comparable, became the universal yardstick: eat fewer of them, exercise more, and the numbers would work out. Yet anyone who has ever dieted with a friend knows the experience that this model cannot explain. Two people eat identical meals, follow identical plans, and one loses weight easily while the other's blood sugar climbs after nearly every plate. The mismatch has nagged at nutrition science for decades, and the emerging explanation for it turns out to be far stranger than a simple failure of willpower. Two equally disciplined dieters, it now seems, may simply be hosting two biological reactors that process the same food in opposite ways, so that the rulebook that worked for one was never going to work for the other.

B. The clue came when researchers began monitoring people continuously rather than at clinic visits. When thousands of volunteers wore sensors tracking their blood sugar around the clock and recorded everything they ate, the same food produced staggeringly different responses in different people. White bread, by the calorie's logic, should raise everyone's glucose by roughly the same amount; in practice, one person's post-meal spike could be mild while another's soared far higher from the very same slice. The variation was not random noise. It tracked something living inside each person — the trillions of bacteria, fungi and viruses that occupy the gut and collectively weigh as much as the brain. Two identical mouthfuls are, it turns out, digested by two entirely different ecosystems, and it is those ecosystems, not the mouthful itself, that decide what the body ultimately sees. A potato that sends one friend's sugar soaring may leave another barely stirred, and an egg that bedevils one person can be eaten freely by the next. The calorie, which pretended all food was interchangeable, quietly begins to look like a crude and misleading measure, a ruler that was never quite straight. The same meal, measured by the same yardstick, simply does not mean the same thing to two different bodies.

C. The gut microbiome does not merely help digest food; it acts as a chemical factory the host did not have to evolve. Fibre, for example, is indigestible to human enzymes alone, but certain bacteria ferment it in the colon into short-chain fatty acids — butyrate, propionate and their cousins — that do a remarkable range of jobs. They feed the cells lining the intestine, signal to the liver about appetite, modulate the immune system, and appear to reduce low-grade inflammation. A person whose bacteria are good at this trick extracts a benefit from a bowl of beans; a person whose microbiome lacks the right species may pass much of the same fibre through, or react to it uncomfortably. This is the biological reason why the same bean can be either a friend or a foe to the gut that receives it. Dietary patterns rich in fibre and in the Mediterranean style have, for this reason, been shown to protect some people even from an otherwise Western diet, while leaving others almost untouched. The same bowl of beans can be medicine for one intestine and mere bulk for another, which is why the label "healthy food" can never quite mean the same thing for everyone.

D. Once the variation was documented, the obvious question was whether it could be predicted. Research groups fed machine-learning algorithms a wealth of data — blood measures, body measurements, dietary logs and, crucially, the composition of each person's gut bacteria — and asked them to guess how that individual would respond to a given food. The models, it turned out, forecast personal glucose responses markedly better than formulas based only on calories or carbohydrate counts. In a small trial, volunteers were assigned diets chosen by the algorithm to keep their individual blood sugar steady, and the tailored menus improved glycaemic control even in people on the verge of diabetes. The promise was intoxicating: a stool sample today, a personalised menu tomorrow, engineered around the bacteria you actually carry rather than the ones an average human might, so that the same meal could be advised for one person and forbidden for another. It was, on paper, the end of the one-size-fits-all diet, and a vindication of the dieter's oldest complaint — that the rules never quite worked for them.

E. The reality, as so often, is more modest than the promise. The algorithms that work well in one country have been shown to lose accuracy when transplanted to people with different diets and different bacterial communities; the microbes that thrive on an Italian diet are not the ones found in rural Chinese intestines. It remains unclear how durable the effect is — whether a tailored meal changes the microbiome permanently or merely accommodates it for a season. No serious scientist today believes that the future is a universal diet for everyone, but neither does the evidence yet support the grand claim that every person needs a bespoke microbiome scan. A reasonable position lies between the two extremes: diet clearly matters, but so does the particular gut it lands in. What it does support is the quieter conclusion that the same meal is not, biologically, the same meal for two different stomachs — and that eating, for all its familiarity, is a far more individual act than the old pyramids ever admitted. A plate, it turns out, is read differently by every stomach it reaches, and the universal diet was always a polite fiction.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. Two people, two wildly different reactions to the same food ii. The democratic assumptions behind the old food pyramids iii. How gut bacteria quietly do chemistry the host cannot iv. Can the difference be forecast before the meal? v. A measured check on the personalised-nutrition dream vi. The history of the calorie as a scientific unit vii. Why fasting cures every metabolic disease

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

Choose the correct letter, A, B, C or D.

5. What does continuous monitoring reveal about the same food? A. It raises everyone's blood glucose by the same amount. B. It produces very different blood-sugar responses between individuals. C. It has no effect on blood glucose at all. D. It affects only people who are overweight.

6. What role do gut bacteria play with dietary fibre? A. They destroy it entirely. B. They ferment it into short-chain fatty acids useful to the body. C. They prevent it from ever reaching the colon. D. They convert it directly into sugar.

7. What did the machine-learning models achieve? A. They predicted individual glucose responses better than calorie-based formulas. B. They cured diabetes in all volunteers. C. They replaced the need for any diet at all. D. They worked identically in every country tested.

8. According to the final paragraph, what limits the approach? A. Gut bacteria cannot be studied at all. B. Models trained in one setting may lose accuracy elsewhere and durability is uncertain. C. Personalised menus are impossible to prepare. D. The calorie has now been completely abandoned.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. Traditional dietary advice has assumed a fairly uniform response to the same food.
10. Human enzymes alone can fully digest fibre in the small intestine.
11. In one small trial, algorithm-tailored menus improved glycaemic control.
12. A microbiome scan now gives a permanently accurate personalised diet for life.
13. The human gut microbiome weighs more than the human brain.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

Gut bacteria ferment fibre into short-chain (14) __________ acids, which feed the cells lining the intestine and help modulate the (15) __________ system.

答案与解析

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