Spam: what the studies weigh, and what they never measured

Spam is canned pork, and almost everything we can tell you about it comes from research on processed meat in general rather than on the can. Two studies name it. Among 2001 American Indian adults followed for five years, the quarter eating the most spam had about double the odds of developing diabetes (OR 2.06). In that same cohort the processing carried the signal: processed meat went with 63 percent higher odds while unprocessed red meat showed no link at all. Both results are observational, so they describe a pattern in people who already ate that way and cannot show what eating spam does to you. The firmest number on this page is a limit. An umbrella review of 164 systematic reviews puts the practical line at under 50 g of processed meat a day, and a single slice of spam, weighed at 56 g in the USDA portion table, is already past it. The two nitrite studies here gave people sodium nitrite on its own as a measured dose, one of them by mouth and by vein in nine adults. Neither fed anyone spam, so read them as chemistry rather than dinner. We hold no card on the safety of the canned meat itself, so the safety section below is about the curing salt and nothing else. We have no USDA composition record for spam in this cohort, which means this page carries no sodium figure.

What your body absorbs

• The nitrite that cures canned meat is absorbed almost completely: 98% of an oral dose reached the blood in healthy adults, with little first-pass loss in the liver. — 9 healthy adults, open three-way crossover, oral and intravenous sodium nitrite (n = 9) Evidence B source
  Absolute bioavailability 98% at the higher oral dose and 95% at the lower one

What cooking and storage change

• In the same cohort the processing, not the meat, carried the signal: processed meat was tied to 63% higher odds of diabetes (OR 1.63) while unprocessed red meat was not tied to it at all. — 2001 American Indian adults, 5-year follow-up, 243 incident cases of diabetes (n = 2001) Evidence C source
  Processed meat OR 1.63 (95% CI 1.21 to 2.63); unprocessed red meat OR 0.90 (95% CI 0.59 to 1.37)
• Pooling 31 observational studies, processed meat intake went with a 65% higher risk of colorectal polyps, while the link with adenomas did not reach significance (RR 1.14). — 31 observational studies of meat subtypes and precancerous colorectal lesions, published up to December 2024 (n = 31 studies) Evidence C source
  Colorectal polyps RR 1.65 (95% CI 1.05 to 2.61); colorectal adenomas RR 1.14 (95% CI 0.93 to 1.41)

What it does to your health

• In a cohort of 2001 American Indian adults, those in the top quarter of spam intake had roughly double the odds of developing diabetes over 5 years compared with the bottom quarter (OR 2.06). — 2001 American Indian adults free of diabetes and cardiovascular disease at baseline, Strong Heart Family Study, 5-year follow-up, 243 incident cases (n = 2001) Evidence C source
  Odds ratio 2.06 (95% CI 1.30 to 3.27), top vs bottom quartile of spam intake
• The size of the effect is small and the evidence weak: across 55 cohorts and over 4 million people, cutting processed meat by 3 servings a week gave only a very small drop in death and cardiometabolic risk, on low-certainty evidence. — 61 articles reporting on 55 cohorts, more than 4 million participants, adults (n = 4000000) Evidence C source
  Very small risk reduction per 3 fewer servings a week; certainty of evidence rated low
• Each daily serving of processed meat went with 0.26 kg of weight gained per year in pooled cohort data on 381 291 adults, an association the authors call very weak. — 11 cohort studies (6 unique), adults; weight model on 381 291 people, waist model on 51 310 (n = 381291) Evidence C source
  +0.26 kg/year per daily serving (95% CI 0.03 to 0.48); waist +0.14 cm/year (95% CI 0.02 to 0.26)
• A Hawaii case-control study of 326 lung cancer patients found rising risk in women with rising intake of bacon and Spam, alongside a positive trend for nitrite intake in men. — 226 men and 100 women with lung cancer and 865 matched community controls, Oahu, Hawaii, 1983 to 1985 (n = 1191) Evidence C source
  Positive dose-response trend for bacon and Spam in women; positive trend for nitrite and dimethylnitrosamine intake
• An umbrella review of 164 systematic reviews put the practical line at under 50 g of processed meat a day to lower cardiovascular risk, which is less than one slice of spam as the USDA portion table weighs it, at 56 g. — umbrella review of 164 systematic reviews published 2014 to 2021, written to support national dietary guidelines (n = 164 reviews) Evidence A source
  Recommended limit under 50 g/day of processed meat for lower cardiovascular disease risk

Safety, limits and interactions

• Capsules of sodium nitrite at 80 or 160 mg a day for 10 weeks raised plasma nitrite 5 to 15 fold in middle-aged and older adults, with no symptomatic hypotension and no clinically relevant rise in methaemoglobin. That is a supervised trial dose of the curing salt on its own, not a safety finding about canned meat. — middle-aged and older adults, randomised double-blind placebo-controlled dosing for 10 weeks (n = -) Evidence B source
  Plasma nitrite up 5 to 15 fold (P < 0.001); no symptomatic hypotension or clinically relevant methaemoglobin rise

The bottom line

The useful question about spam is how often, and the pooled answers are smaller than the reputation of processed meat suggests. Across 55 cohorts and more than 4 million people, eating three fewer servings of processed meat a week gave only a very small drop in death and cardiometabolic risk, and the reviewers rated that evidence low certainty. Weight moves slowly too: 0.26 kg a year for each daily serving, pooled across 381 291 adults, and the authors themselves call the association very weak. On cancer the picture splits. Pooling 31 observational studies, processed meat went with a 65 percent higher risk of colorectal polyps, while the link with adenomas did not reach statistical significance. A Hawaii case-control study of 326 lung cancer patients, run between 1983 and 1985, found risk rising in women as bacon and Spam intake rose, with a similar trend for nitrite in men. In that study the association was stronger in heavy smokers, and smoking is hard to separate from what people ate. Every one of those designs watches people who chose their own food. None of them tested a change. Now the part that is missing, because you should know it is missing. Nothing in our evidence says who should be careful with spam. The single safety study we hold gave middle-aged and older adults 80 to 160 mg of sodium nitrite a day for ten weeks and saw no symptomatic drop in blood pressure and no meaningful rise in methaemoglobin. That tells you about that dose in those people. It says nothing about pregnancy, kidney disease, blood pressure medicine, or children, and we have no card on any of them. Nitrite from a capsule also behaves like a drug: 98 percent of an oral dose reached the blood in the nine adults who were tested, which is a fact about the compound and not about a slice of meat. We also hold no USDA composition entry for spam in this cohort, so we cannot print its sodium, fat or protein, and sodium is the first thing most people came here for. Read the label on the can for that. Until those gaps close, treat this page as a page about processed meat that happens to name spam twice.

Sources

1. spam-r1-06 · randomised crossover trial
   Absolute bioavailability of nitrite was 98% after oral administration of 0.12 mmol NaNO(2)/mmol Hb, and 95% after oral administration of 0.06 mmol NaNO(2)/mmol Hb.
   Toxicol Lett, 2009 · checked 2026-09-23
2. spam-r1-02 · prospective cohort study
   In a comparison of upper and lower quartiles, intake of processed meat was associated with a higher risk of incident diabetes (OR: 1.63; 95% CI: 1.21, 2.63), after adjustment for potential confounders. ... Intake of unprocessed red meat was not associated with incident diabetes (OR for the comparison of upper and lower quartiles: 0.90; 95% CI: 0.59, 1.37).
   Am J Clin Nutr, 2012 · checked 2026-09-23
3. spam-r1-03 · systematic review and meta-analysis
   Processed meat consumption was correlated with increased colorectal polyp risk (1.65; 1.05, 2.61) but not colorectal adenoma risk (1.14; 0.93, 1.41).
   Nutr Rev, 2026 · checked 2026-09-23
4. spam-r1-01 · prospective cohort study
   The relation was particularly strong for spam (OR for the comparison of upper and lower quartiles: 2.06; 95% CI: 1.30, 3.27).
   Am J Clin Nutr, 2012 · checked 2026-09-23
5. spam-r1-04 · systematic review and meta-analysis
   Likewise, low-certainty evidence was found that a reduction in processed meat intake of 3 servings per week is associated with a very small decrease in risk for all-cause mortality, cardiovascular mortality, stroke, MI, and type 2 diabetes.
   Ann Intern Med, 2019 · checked 2026-09-23
6. spam-r1-05 · systematic review and meta-analysis
   Three studies (n = 381 291) were included in the random-effects model of measured body weight, resulting in a summary increase of 0.26 kg/y per 1 daily serving of processed meat (95% confidence interval [CI], 0.03-0.48; τ2: 0.03; I2: 92.95%).
   Nutr Rev, 2025 · checked 2026-09-23
7. spam-r1-08 · case-control study
   We also found a positive trend in the risk of lung cancer in women with increasing intake of some processed meats (bacon, Spam) and desserts (cakes, custard/cream pies).
   Epidemiology, 1992 · checked 2026-09-23
8. spam-r1-09 · umbrella review
   Limiting processed meat intake to <50 g/d reduces CVD risk.
   Adv Nutr, 2023 · checked 2026-09-23
9. spam-r1-07 · randomised double-blind placebo-controlled trial
   Ten weeks of sodium nitrite (80 or 160 mg/day, capsules, TheraVasc; randomized, placebo control, double blind) increased plasma nitrite acutely (5- to 15-fold, P < 0.001 vs. placebo) and chronically (P < 0.10) and was well tolerated without symptomatic hypotension or clinically relevant elevations in blood methemoglobin.
   J Appl Physiol (1985), 2016 · checked 2026-09-23