Interpreting a Nutrition Label Against a Daily Target
A student is tracking sodium and fibre using a food label. One serving of a canned soup is 250 mL and contains 640 mg sodium, 3 g fibre, and 180 Calories. The can holds 500 mL, and the student usually eats the whole can as one meal. Health guidance the student follows: keep sodium under 2,300 mg per day and aim for at least 25 g fibre per day. The student's other meals that day provide 1,500 mg sodium and 14 g fibre. The student wants to know whether eating the whole can fits the sodium limit, how it affects the fibre goal, and what a reasonable portion would be.
1. Calculate the sodium and fibre from eating the whole can, and compare with the daily limits given the other meals.
Read the worked answer
The can is 500 mL, which is 2 servings (500 / 250 = 2).
Whole can: sodium = 2 × 640 = 1,280 mg; fibre = 2 × 3 = 6 g; Calories = 2 × 180 = 360.
Other meals provide 1,500 mg sodium and 14 g fibre. Daily totals with the whole can: sodium = 1,500 + 1,280 = 2,780 mg, which exceeds the 2,300 mg limit by 480 mg. Fibre = 14 + 6 = 20 g, which is 5 g short of the 25 g goal.
So the whole can breaks the sodium limit and still leaves the fibre goal unmet.
2. Determine the largest portion of the can (in mL, to the nearest 50 mL) that keeps total sodium at or below 2,300 mg.
Read the worked answer
Sodium per mL = 640 mg / 250 mL = 2.56 mg/mL.
Sodium budget remaining after other meals = 2,300 - 1,500 = 800 mg.
Maximum volume = 800 / 2.56 = 312.5 mL. Rounding down to the nearest 50 mL gives 300 mL.
Check: 300 mL × 2.56 = 768 mg, total sodium = 2,268 mg, which is under 2,300 mg. At 350 mL, sodium = 896 mg, total = 2,396 mg, which exceeds the limit. So 300 mL is the largest portion in 50 mL steps.
3. Suggest how the student could meet the fibre goal that day and evaluate whether adding a high-fibre snack creates a sodium problem.
Read the worked answer
With a 300 mL portion, fibre from soup = 300 / 250 × 3 = 3.6 g. Total fibre = 14 + 3.6 = 17.6 g, leaving 25 - 17.6 = 7.4 g to reach the goal.
A snack such as 1 cup of cooked lentils provides roughly 8 g fibre and very little sodium (about 5 mg unsalted), which closes the fibre gap without threatening the sodium limit. Remaining sodium budget = 2,300 - 1,500 - 768 = 32 mg, so the snack must be low-sodium; salted snacks or canned beans with added salt could easily add 300-500 mg and break the limit.
Conclusion: a low-sodium, high-fibre snack like unsalted lentils or beans meets the fibre goal while keeping sodium under 2,300 mg.