Plain-language note: how juice affects sugar after bread
What was tested
Bread was washed down with half a glass of lemon juice mixed with water.
- healthy people
- one type of food: bread
Lower peak
The rise in sugar at the peak was about a third lower.
- this is the peak, not all the sugar
- the juice made the rise smoother
Later peak
The peak came almost 40 minutes later.
- sugar rose more slowly
- the same amount was absorbed
What did not change
The total sugar rise over 3 hours was the same.
- the juice smooths the curve
- it does not reduce the total
Tea did not help
Black tea did not affect sugar.
- it is the acid in the juice
- tea gave no such effect
Protect your teeth
Acidic drinks are linked to enamel erosion.
- drink quickly and with the meal
- do not hold juice in your mouth
- do not sip it over an hour
Not a treatment
Juice does not replace prescribed treatment.
- the trials were in healthy people
- no data for other foods
When to see a doctor
If sugar is repeatedly below 3.0 mmol/L (54 mg/dL) or above 8.9 mmol/L (160 mg/dL), and with heartburn, gastritis or an ulcer.
- with diabetes, targets are individual
Important. Important: prescribed diabetes treatment is not changed on your own.
Key points
If you wash bread down with lemon juice diluted half and half with water, blood sugar rises lower and later. In a small trial in healthy people the rise in glucose at the peak was 30% lower and came 37 minutes later. The method is simple, but acidic drinks must be taken in a way that does not harm teeth.
| What | How much | How it helps | What studies showed |
|---|---|---|---|
| Lemon juice with water with bread | Half a glass of juice mixed with water (250 mL in total) for 100 g of bread | Lower glucose peak | 17 healthy adults: rise at the peak 30% lower, at minute 78 instead of 41 |
| Total rise over 3 hours | n/a | The same | No significant difference: the same glucose absorbed, but more slowly |
| Repeat trial | The same conditions | Lower rise at one hour | 10 healthy men: rise 35% lower at minute 55, stomach emptied 1.5 times faster |
| Black tea | 250 mL | No effect | Glucose did not change (Freitas 2021) |
| The next meal | n/a | Did not change | Food eaten 3 hours later did not differ |
How to use it
In the trial, bread was washed down with lemon juice; the bread was only a condition of the experiment, not advice. If you want to try it, dilute the juice half and half with water, drink it in one go during the meal and do not hold it in your mouth. These studies say nothing about other foods, so do not expect lemon juice to "cancel" any dessert.
To protect your teeth, do not sip the drink over an hour and do not swish it. Acidic drinks are linked to enamel erosion at any time of day.
A real-life example
A woman of 40 has a salad with baked fish at lunch and is used to washing her food down with sweet tea. She makes a dressing of olive oil and lemon juice and drinks water. It is a tasty swap for a sweet drink, not a treatment: in the trials bread was washed down with lemon juice, and there are no such data for salad and fish.
What the studies showed
In a randomised crossover trial, 17 healthy adults ate 100 g of bread and drank 250 mL of water, black tea or diluted lemon juice. The juice lowered the glucose rise at the peak by 30% (above fasting level, from 2.7 to 1.8 mmol/L, 49 to 32 mg/dL) and moved it: the peak came at minute 78 versus 41 with water. The area under the glucose curve over 3 hours did not differ significantly (Freitas D Eur J Nutr 2021. PMID 32201919[1]).
In a repeat trial in 10 healthy men, lemon juice lowered the glucose rise above baseline by 35% at minute 55. The stomach emptied 1.5 times faster, and black tea had no effect (Freitas D Eur J Nutr 2022. PMID 35013789[2]).
About teeth: in a study of 300 people with enamel erosion and 300 without, acidic drinks were linked to erosion whatever the time of intake. The habit of holding a drink in the mouth was particularly important: its association was comparable to three or more acid intakes a day (O'Toole S J Dent 2017. PMID 27856311[3]).
Who should see a doctor first
If you measure your glucose, see a doctor if the result is repeatedly below 3.0 mmol/L (54 mg/dL) or above 8.9 mmol/L (160 mg/dL). With diabetes, targets are individual; below 3.0 mmol/L (54 mg/dL) always means a doctor.
Prescribed diabetes treatment is not changed on your own. With heartburn, gastritis or an ulcer, acidic drinks may make symptoms worse: ask your doctor. See a dentist if your teeth are sensitive.
Bottom line
Lemon juice diluted with water, drunk with bread, made the rise in glucose at the peak lower and later in small trials. The bread was a condition of the experiment, not advice; it was tested with one type of food and is not a treatment; drink it quickly and do not hold it in your mouth.
References
- Freitas D Eur J Nutr 2021. PMID 32201919
- Freitas D Eur J Nutr 2022. PMID 35013789
- O'Toole S J Dent 2017. PMID 27856311
Key facts
- 100 g of bread with diluted lemon juice: in 17 healthy adults the rise in glucose at the peak was 30% lower (p < 0.01; above fasting level 2.7 → 1.8 mmol/L, 49 → 32 mg/dL) and later, at minute 78 versus 41 with water (Freitas D Eur J Nutr 2021. PMID 32201919).
- The total glucose rise over 3 hours did not differ significantly: the same amount of glucose was absorbed, but more slowly (Freitas D Eur J Nutr 2021. PMID 32201919).
- In a repeat trial in 10 healthy men, the glucose rise above baseline at minute 55 was 35% lower, and the stomach emptied 1.5 times faster (Freitas D Eur J Nutr 2022. PMID 35013789).
- Black tea had no effect on glucose, and lemon juice did not change the next meal's food intake (Freitas D Eur J Nutr 2021. PMID 32201919).
- Acidic drinks are linked to tooth enamel erosion at any time of day; holding the drink in the mouth is also strongly linked to it (O'Toole S J Dent 2017. PMID 27856311).
