Lasagna: a dish the science has only studied in pieces

Almost nothing has been tested on lasagna as a dish. What exists is science on its parts, pasta, tomato sauce and the ready meal as a category, and that has to be said before any number on this page. The numbers themselves are plain enough. A one-sixth piece of an 8 inch lasagna weighs about 206 g with meat and 227 g without. Per 100 g, a British homemade lasagne carries 180 kcal, 9.6 g of fat and 235 mg of sodium, and a reheated retail one 143 kcal and 210 mg of sodium. The three US records for frozen lasagna run from 284 to 445 mg of sodium per 100 g, close to twice the British homemade figure, and the recipes behind the two datasets cannot be reconciled. The one large piece of evidence is about pasta. Across 32 trial comparisons with 2448 adults, pasta eaten inside a low glycaemic index diet, meaning a diet built from foods that raise blood sugar slowly, came with 0.63 kg less body weight and 0.26 less BMI than higher glycaemic diets, with moderate certainty. No trial in that review fed pasta on its own. The trials measured a whole pattern of eating, and lasagna was never the thing on the plate. The cooked tomato layer has a trial of its own. In 12 adults a tomato sauce heat-processed so that much of its lycopene had changed into the cis form delivered 54 percent more lycopene into blood fats than a sauce rich in the ordinary all-trans form, 7.30 against 4.74 nmol h/L. The only trial that put lasagna itself on the plate fed vegetarian lasagna to 13 women with low iron stores and found that adding 100 mg of ascorbic acid, which is vitamin C, raised how much iron they absorbed. The abstract does not say by how much.

The numbers, per 100 g

How much is actually in it

• A one-sixth piece of an 8 inch lasagna weighs about 206 g with meat or 227 g meatless, and per 100 g British homemade lasagne carries 180 kcal, 9.6 g fat and 235 mg sodium. Retail reheated lasagne has 143 kcal and 210 mg sodium, while US frozen and baked records run 284 to 445 mg sodium. — CoFID 2021 rows 19-481 Lasagne homemade, 19-523 Lasagne retail reheated, 15-651 Lasagne vegetable retail; FNDDS 2021-2023 portions 2708750 and 2708758; USDA SR Legacy lasagna records (3, no Foundation spread) (n = three CoFID rows, three USDA records) Evidence E source
  Per 100 g CoFID homemade / retail reheated / vegetable retail: energy 180 / 143 / 117 kcal, fat 9.6 / 6.1 / 5.3 g, protein 9.6 / 7.4 / 4.8 g, calcium 104 / 80 / 73 mg, iron 0.80 / 1.00 / 0.80 mg, sodium 235 / 210 / 210 mg; USDA sodium 284 to 445 mg across 3 records, selenium 14.1 to 26.2 ug, vitamin B12 0.1 to 0.59 ug; FNDDS 1 piece 1/6 of 8 inch square 206 g meat and 227 g meatless, 1 cup 250 g

What your body absorbs

• In 13 women with low iron stores, non-haem iron absorption from a vegetarian lasagna meal rose when either 100 mg of ascorbic acid or the meat factor compound L-alpha-glycerophosphocholine was added at a 2 to 1 enhancer to iron ratio. — 13 women of child-bearing age with low iron stores, vegetarian lasagna test meals labelled with stable iron isotopes, 10 mg iron per meal (n = 13) Evidence B source
  Non-haem iron absorption increased with ascorbic acid (P = 0.010) and with L-alpha-GPC (P = 0.023); magnitudes not in the abstract
• In 12 healthy adults, 150 g of tomato sauce heat-processed to be rich in cis-lycopene delivered 54 percent more lycopene into blood lipoproteins than an all-trans-rich sauce, 7.30 versus 4.74 nmol h/L. Both sauces were heat-processed tomato and no raw tomato was tested, so this compares two cooked sauces with each other. — 12 healthy adults, randomised crossover, 150 g tomato sauce in a standard breakfast, 9.5 h plasma TAG-rich lipoprotein sampling, 2-week washouts (n = 12) Evidence B source
  Total lycopene AUC 7.30 vs 4.74 nmol h/L (P = 0.002); cis-lycopene 3.80 vs 1.98 (P = 0.0005); all-trans 3.50 vs 2.76 (P = 0.01)

What cooking and storage change

• An 11-year-old girl developed liver failure, rhabdomyolysis, clotting failure and acute kidney injury 40 hours after eating a whole platter of lasagna cooked 3 days earlier and contaminated with a cereulide-producing Bacillus cereus strain, while her sister who ate a few bites had mild symptoms. — two sisters aged 11 and 13, France, pasta dish cooked 3 days earlier (n = 2) Evidence C source
  Multi-organ failure requiring ventilation, haemofiltration and vasopressors in the child who ate the whole platter; survival after toxin removal and antibiotics

What it does to your health

• Across 32 randomised trial comparisons with 2448 adults, pasta eaten within low glycaemic index diets reduced body weight by 0.63 kg and BMI by 0.26 compared with higher GI diets, with moderate certainty, and no trial has tested pasta on its own. — 2448 adults in 32 trial comparisons of at least 3 weeks, pasta within low-GI dietary patterns versus higher-GI patterns, searched to February 2017 (n = 2448) Evidence A source
  Body weight MD -0.63 kg (95% CI -0.84 to -0.42); BMI MD -0.26 kg/m2 (95% CI -0.36 to -0.16); no effect on waist or body fat
• In 26 women, a ready meal with the same calories but lower energy density and a larger portion reduced hunger and increased fullness through the afternoon compared with a denser ready meal, without changing how much they ate at the evening meal. — 26 women aged 18 to 65, mean BMI 28.8, randomised crossover, equicaloric commercial ready meals at lunch, ad libitum tea 4 hours later (n = 26) Evidence B source
  Hunger lower and fullness higher after the low energy-dense meal (both p < 0.001); no difference in evening energy intake; whole-day fat intake 7.1% lower

Safety, limits and interactions

• The USDA purchasing specification for frozen lasagna caps sodium at less than 1200 mg per 227 g (8 oz) serving of finished product, which is about half the 2300 mg daily limit in a single serving. — USDA Agricultural Marketing Service Commercial Item Description A-A-20260A, frozen lasagna, 2013 Evidence E source
  Sodium tolerance less than 1,200 mg per 227 g serving; beef, pork or both permitted as meat

What people believe that the data does not support

• Shown the larger serving sizes of the proposed US Nutrition Facts label, 61 consumers bought 43 percent more lasagnas for others and cut a lasagna into 22 percent larger slices than those shown the old label. Separately, 78 percent of people believed the serving size is how much one should eat. — US adults in four experiments (N = 101, 51, 60 and 61), current versus proposed Nutrition Facts label (n = 61) Evidence B source
  Proposed label: 41% more cookies served to self, 27% more crackers served to others, 43% more lasagnas bought and 22% larger slices; 78% misread serving size as a recommendation
• US labelling law uses lasagna as its worked example for reduced-calorie claims: a product may say 25 percent fewer calories only if the reference food and the percentage difference sit next to the claim. The food must also have at least 25 percent fewer calories per 100 g. — 21 CFR 101.60, nutrient content claims for the calorie content of foods, paragraph (b)(4)(i)(A) Evidence E source
  Reduced calorie claim requires at least 25 percent fewer calories per 100 g than the reference food and disclosure of the reference and the difference

Who this works differently for

• FDA Total Diet Study data for 2014 to 2016 put US children's mean dietary lead exposure at 1 to 3.4 ug per day, with mixed dishes such as hamburgers, pizza, lasagna and soups among the major contributors alongside grains, fruit and dairy. — US children aged 1 to 6, FDA Total Diet Study 2014-16 concentrations combined with WWEIA/NHANES consumption Evidence E source
  Mean lead exposure 1 to 3.4 ug/day depending on age band and non-detect handling; cadmium 0.38 to 0.44 ug/kg bw/day; lead declined slightly since 2004-08, cadmium did not

What is still unknown

• Among 1893 Qatari adults after bariatric surgery, a traditional dietary pattern that included lasagna alongside biryani, meat dishes and Arabic bread was associated with 39 percent lower odds of diabetes across extreme quartiles, and weight loss was the main determinant. — 1893 adults with a history of bariatric surgery, Qatar Biobank, food frequency questionnaire, factor-analysis patterns (n = 1893) Evidence C source
  Traditional pattern OR for diabetes 0.61 (95% CI 0.41 to 0.99) Q4 vs Q1; remission OR 5.94 for extreme quartiles of weight loss

The bottom line

If lasagna is a regular meal for you, sodium is the number to watch, and it is the number our two datasets disagree on most. The frozen lasagna the US government buys for its own programmes may carry anything under 1200 mg of sodium in a 227 g serving, about half of the 2300 mg daily limit in one piece. That ceiling applies to federal purchasing. A supermarket box is under no such rule, so read the panel on the box. Read the serving size with care too. Shown the larger serving sizes of the redesigned US Nutrition Facts label, 61 shoppers bought 43 percent more lasagnas for other people and cut their lasagna into 22 percent larger slices. In the same work 78 percent of people believed the serving size is how much you are meant to eat. It is a measuring unit for the label. On appetite there is one hint, and it is about ready meals in general. In 26 women a lunch with the same calories but a larger, less dense portion left them less hungry and fuller through the afternoon, and they ate no less at the evening meal. In our data the vegetable retail lasagne is the least dense at 117 kcal per 100 g against 180 for homemade, but that link is ours, and nobody has run the trial with lasagna. Two safety points stand. Leftovers first. In one French family an 11-year-old girl went into liver and kidney failure 40 hours after eating a whole platter of lasagna cooked 3 days earlier and contaminated with a toxin-producing Bacillus cereus, while her sister, who ate a few bites, was only mildly ill. That is a single case report, and the dose difference between the sisters is the lesson: how long and how warm a cooked dish sits are the two things you control. Second, lead. The FDA Total Diet Study for 2014 to 2016 put US children aged 1 to 6 at 1 to 3.4 micrograms of lead a day from food, with mixed dishes such as lasagna, pizza and soups among the main contributors. Lasagna is on that list because small children eat a lot of mixed dishes. The study does not say lasagna carries more lead than other food, and it also says no level of lead is known to be safe. What is missing matters as much as what is here. We found no trial of lasagna as a whole dish on any outcome, no data on what baking does to its nutrients, and no allergy or intolerance literature on it by name. So this page cannot tell you who should be careful with it beyond sodium and leftovers. If you are pregnant, feeding a small child or on a doctor-set low-sodium diet, treat the silence here as a gap in the research and ask the person treating you. One observational study from Qatar found that 1893 adults who had bariatric surgery and ate a traditional pattern that happened to include lasagna had 39 percent lower odds of diabetes, and the authors put the result down to weight loss. It says nothing about lasagna, and we list it so that nobody quotes it at you as if it did.

Sources

1. lasg-c5-10 · reference dataset
   CoFID 19-481 Lasagne, homemade: Energy 180 kcal · Fat 9.6 g · Protein 9.6 g · Calcium 104 mg · Iron 0.80 mg · Sodium 235 mg · AOAC fibre 1.0 g || CoFID 19-523 Lasagne, retail, reheated: Energy 143 kcal · Fat 6.1 g · Protein 7.4 g · Calcium 80 mg · Iron 1.00 mg · Sodium 210 mg || CoFID 15-651 Lasagne, vegetable, retail: Energy 117 kcal · Fat 5.3 g · Protein 4.8 g · Sodium 210 mg || FNDDS 2708750 Lasagna with meat: 1 piece (1/6 of 8 inch square) 206 g · 1 cup 250 g || FNDDS 2708758 Lasagna, meatless: 1 piece (1/6 of 8 inch square) 227 g || USDA SR Legacy lasagna, 3 records: sodium 284-445 mg · selenium 14.1-26.2 ug · vitamin B12 0.1-0.59 ug per 100 g
   CoFID 2021, Public Health England / OGL v3.0; FNDDS 2021-2023; USDA FoodData Central SR Legacy · checked 2026-09-23
2. lasg-c5-01 · randomised crossover trial
   We added a commercially available food grade source of L-alpha to vegetarian lasagna, with and without 100 mg ascorbic acid (a known enhancer of nonheme iron absorption), at the same enhancer:iron molar ratio (2:1), and fed meals to 13 women of child-bearing age with low iron stores. ... Nonheme iron absorption from lasagna was increased by the addition of either ascorbic acid (P = 0.010) or L-alpha (P = 0.023).
   J Nutr, 2008 · checked 2026-09-23
3. lasg-c5-04 · randomised crossover trial
   Two tomato sauces, one rich in all-trans-lycopene (32.5 mg total lycopene/100 g sauce; 5 % cis-isomers), the other high in cis-lycopene (26.4 mg total lycopene/100 g sauce; 45 % cis-isomers), were produced by different heat-processing techniques. ... AUC values adjusted for the amount lycopene consumed showed that total, total cis-, and all-trans-lycopene responses were significantly higher from the cis-isomer-rich sauce, compared with the all-trans-rich sauce, being 7.30 (sem 1.45) v. 4.74 (sem 1.08) nmol x h/l (P = 0.002)
   Br J Nutr, 2007 · checked 2026-09-23
4. lasg-c5-05 · case report
   After eating a few bites of pasta cooked 3 days earlier, a 13-year-old girl developed mild symptoms. However, her 11-year-old sister suffered, 40 h after ingestion of the entire platter, a multi-organ failure including acute liver failure, rhabdomyolysis, disseminated intravascular coagulation, and acute kidney injury (AKI).
   Front Pediatr, 2022 · checked 2026-09-23
5. lasg-c5-03 · meta-analysis of RCTs
   We identified no trial comparisons of the effect of pasta alone and 32 trial comparisons (n=2448 participants) of the effect of pasta in the context of low-GI dietary patterns. Pasta in the context of low-GI dietary patterns significantly reduced body weight (MD=-0.63 kg; 95% CI -0.84 to -0.42 kg) and BMI (MD=-0.26 kg/m2; 95% CI -0.36 to -0.16 kg/m2) compared with higher-GI dietary patterns.
   BMJ Open, 2018 · checked 2026-09-23
6. lasg-c5-11 · randomised crossover trial
   A total of 26 female participants (aged 18-65 years; body mass index of 28.8 ± 3.0 kg·m-2) attended two test days. ... The results revealed that the LEDRM reduced hunger and increased fullness (both p < 0.001). There was no difference in EI at the evening meal between the ready meals (p > 0.05)
   Nutrients, 2021 · checked 2026-09-23
7. lasg-c5-09 · government specification
   Sodium Less than 1,200 mg per 227 g or 8 oz. of finished product
   USDA AMS Commercial Item Description A-A-20260A, Lasagna, Frozen, 2013 · checked 2026-09-23
8. lasg-c5-02 · randomised experiment
   the majority of participants (over 78%) incorrectly believed that the serving sizes refer to how much food can or should be consumed in one sitting as part of a healthy diet. ... In studies 2-4, the proposed label (vs. the current label) led consumers to serve themselves 41% more cookies (study 2); serve 27% more cheese crackers to another person (study 3); and buy 43% more lasagnas for others and divide a lasagna into 22% larger slices (study 4).
   Appetite, 2015 · checked 2026-09-23
9. lasg-c5-08 · regulation
   (A) The identity of the reference food and the percent (or fraction) that the calories differ between the two foods are declared in immediate proximity to the most prominent such claim (e.g., Larry's Reduced Calorie Lasagna, “25 percent fewer calories per oz (or 3 oz) than our regular Lasagna”); and
   21 CFR 101.60, Nutrient content claims for the calorie content of foods · checked 2026-09-23
10. lasg-c5-06 · national survey exposure assessment
    Estimated mean lead exposures range from 1 to 3.4 µg/day, with major contributions from grains, fruit, dairy, and mixtures (e.g. hamburgers, pizza, lasagna, soups).
    Food Addit Contam Part A, 2019 · checked 2026-09-23
11. lasg-c5-07 · cross-sectional study
    The traditional dietary pattern (high intake of Biryani, chicken, meat, fish dishes, zaatar fatayer, croissant, lasagna, and Arabic bread) was inversely associated with diabetes prevalence, with an OR of 0.61 (95%CI, 0.41-0.99) when comparing extreme quartiles.
    Nutrients, 2024 · checked 2026-09-23