American cheese: the trials are about vitamin D, the warning is about salt

The randomised evidence that is genuinely about process cheese is evidence about vitamin D, and it did not work. A daily serving of process cheese fortified with 600 IU of vitamin D3 for two months left 25-hydroxyvitamin D, parathyroid hormone and osteocalcin unchanged in 100 men and women aged 60 and over, tested during a season of limited sunlight. The authors read that as 600 IU a day being too little for winter rather than as cheese being a poor carrier, and a second study in the same paper supports them. In a crossover feeding of 8 adults aged 23 to 84, a single dose of vitamin D2 was given two ways, 5880 IU in a 56.7 g serving of cheese or 32,750 IU in water. It was absorbed more efficiently from the cheese, and peak blood level and 24-hour exposure were similar in the younger and older group. That is eight people, one dose, and a dose nearly ten times the 600 IU a day tested in the other study. The rest of what is known here is about cheese as a category, about salt, and about a question involving aluminium that was never settled.

The numbers, per 100 g

What your body absorbs

• In 8 adults aged 23 to 84, a single feeding delivered 5880 IU of vitamin D2 in a 56.7 g serving of process cheese or 32,750 IU in water. Peak blood level and 24-hour exposure were similar in the younger and the older group, and vitamin D2 was absorbed more efficiently from cheese than from water. — two groups of 4 adults each, younger 23 to 50 years and older 72 to 84 years, given a single feeding of vitamin D2 fortified cheese or water in crossover (n = 8) Evidence B source
  Peak serum vitamin D and area under the curve similar by age, with more efficient absorption from the 5880 IU cheese serving than from the 32,750 IU water dose

What it does to your health

• Pooling 29 prospective cohorts and 1,680,651 people, eating 15 g of cheese a day went with a 5% lower risk of cardiovascular death (HR 0.95, 95% CI 0.91 to 0.99) and with no change in death from all causes. — 1,680,651 healthy adults in 29 prospective cohort studies followed for all-cause and cardiovascular mortality (n = 1680651) Evidence C source
  Cheese 15 g/day, cardiovascular mortality HR 0.95 (95% CI 0.91 to 0.99), all-cause mortality not reduced
• Across 13 cohort studies of coronary heart disease, each extra 20 g of cheese a day went with a 4% lower risk (RR 0.96, 95% CI 0.93 to 0.98), while high-fat milk went the other way. — general adult population in 13 cohort studies for coronary heart disease and 7 for ischaemic stroke (n = 13 cohorts) Evidence C source
  Cheese RR 0.96 (95% CI 0.93 to 0.98) per 20 g/day for coronary heart disease, high-fat milk RR 1.08 (95% CI 1.00 to 1.16) per 200 g/day

Safety, limits and interactions

• The cheese reaction that makes monoamine oxidase inhibitors risky is a hypertensive crisis after foods high in tyramine. In 12 healthy men on transdermal selegiline 6 mg per 24 hours for 13 days, tyramine-enriched meals produced no change in the blood pressure and heart rate readings that the authors counted as meaningful. — 12 healthy adult male volunteers given tyramine challenges during placebo and during 13 days of transdermal selegiline 6 mg per 24 hours (n = 12) Evidence B source
  No change in cardiovascular vital signs that the authors counted as meaningful, after tyramine-enriched meals at pharmacokinetic steady state on the 6 mg per 24 hour patch
• In the rule that governs sodium health claims on labels, the FDA states that cutting sodium intake lowers blood pressure and the risks tied to it in many but not all people, whether or not their blood pressure is already high. — the United States population addressed by federal food labelling rules, covering both hypertensive and normotensive people Evidence E source
  Regulator position that lower sodium intake lowers blood pressure and associated risk in many but not all individuals in both groups

What people believe that the data does not support

• In a pilot case-control study of 46 nursing home residents, American cheese was one of the aluminium-additive foods with raised odds in people who had Alzheimer disease, and the adjusted odds ratio of 8.6 for aluminium-rich foods overall fell short of statistical significance at P=0.19. — 46 residents of one geriatric centre in Syracuse, New York, as 23 matched pairs with and without newly diagnosed Alzheimer disease, with diet reported by next of kin (n = 46) Evidence C source
  Crude odds ratio 2.0 for daily intake of high-aluminium foods, 8.6 after adjustment with P=0.19, with elevated adjusted odds also for American cheese

Who this works differently for

• Giving 100 adults aged 60 and over a daily serving of process cheese fortified with 600 IU of vitamin D3 for 2 months did not change their blood 25-hydroxyvitamin D, parathyroid hormone or osteocalcin. — 100 men and women aged 60 and over, randomised to vitamin D fortified cheese, unfortified cheese or no cheese, during a season of limited sunlight (n = 100) Evidence B source
  No difference in 25-hydroxyvitamin D, parathyroid hormone or osteocalcin after 2 months, with the fortified group falling more because it started higher

The bottom line

Cheese as a category looks mildly favourable in observational data, which is a weaker thing than it sounds. Pooling 29 prospective cohorts and 1,680,651 adults, eating 15 g of cheese a day went with a 5 percent lower rate of cardiovascular death (HR 0.95, 95% CI 0.91 to 0.99) and with no change in death from all causes. Across 13 cohorts of coronary heart disease, each extra 20 g a day went with RR 0.96 (95% CI 0.93 to 0.98). High-fat milk went the other way in the same paper, at RR 1.08 (95% CI 1.00 to 1.16) per 200 g a day. The authors report heterogeneity between studies in the high versus low comparison. Cohorts show association and not cause. Cheese in these pools means every cheese together, and processed cheese was not separated out. Salt is the part of this product that has a number. The USDA Foundation entry for restaurant American cheese lists 1600 mg of sodium per 100 g, and the sampled units ranged from 1240 to 1860 mg. In the rule governing sodium claims on labels, the FDA states that reducing sodium intake lowers blood pressure and associated risks in many but not all hypertensive people, and in many but not all normotensive people. The words in many but not all are the regulator being careful, and they are usually dropped when the rule is quoted. The cheese reaction that rules out cheese for people taking monoamine oxidase inhibitors comes from tyramine, which builds up in cheese as it ages. In a challenge trial, 12 healthy men on a transdermal selegiline patch at 6 mg per 24 hours for 13 days ate tyramine- enriched meals, and the cardiovascular readings taken showed no change the authors counted as meaningful. That is one drug, one dose and twelve healthy men, and the abstract does not say how much tyramine those meals carried, so nothing here sets an amount of cheese that is safe on a monoamine oxidase inhibitor. If you take an antidepressant of that class, the question belongs to the person who prescribed it. American cheese also appears by name in the aluminium and Alzheimer disease question. In a pilot study of 46 residents of one geriatric centre in Syracuse, handled as 23 matched pairs with diet reported by relatives after diagnosis, daily intake of high-aluminium foods carried a crude odds ratio of 2.0, and 8.6 after adjustment, at P=0.19. Odds are odds and not risk, the headline figure missed statistical significance, and American cheese was one of several foods with elevated adjusted odds. That is a question somebody raised in 1999 and nobody answered on a larger sample. We found no trial testing American cheese itself against any health outcome, and nothing here on how much of it a person actually eats at a sitting.

Sources

1. amch-r1-01 · crossover feeding trial
   A second study was conducted to determine whether the bioavailability of vitamin D2 in cheese (delivering 5880 IU of vitamin D2/56.7-g serving) and water (delivering 32,750 IU/250 mL) is similar and whether absorption differs between younger and older adults...Peak serum vitamin D and area under the curve were similar between younger (23 to 50 yr) and older (72 to 84 yr) adults, and vitamin D2 was absorbed more efficiently from cheese than from water.
   J Dairy Sci, 2005 · checked 2026-09-24
2. amch-r1-03 · systematic review and meta-analysis of cohorts
   From 4,797 retrieved articles, 29 prospective cohort studies involving 1,680,651 participants were included...Cheese intake (15 g/day) was linked to a lower risk of CVD mortality only (HR: 0.95; 95% CI: 0.91, 0.99).
   Front Nutr, 2026 · checked 2026-09-24
3. amch-r1-04 · systematic review and meta-analysis of cohorts
   High-fat milk was positively associated with CHD (RR 1.08 (95% confidence interval 1.00-1.16) per 200 g higher intake/day) and cheese was inversely associated with CHD (RR 0.96 (95% confidence interval 0.93-0.98) per 20 g higher intake/day). Heterogeneity, however, was observed in high versus low meta-analyses.
   Sci Rep, 2021 · checked 2026-09-24
4. amch-r1-05 · phase I challenge trial
   Monoamine oxidase inhibitors are well recognized as effective antidepressant agents but are rarely used due, in part, to the risk of hypertensive crisis following the ingestion of foods high in tyramine ("cheese reaction")...Ingestion of tyramine-enriched meals following 13 consecutive days of treatment with the STS 6 mg/24 hr (pharmacokinetic steady-state) produced no clinically significant changes in cardiovascular vital signs in 12 healthy adult male subjects.
   CNS Spectr, 2007 · checked 2026-09-24
5. amch-r1-07 · federal regulation
   The scientific evidence indicates that reducing sodium intake lowers blood pressure and associated risks in many but not all hypertensive individuals. There is also evidence that reducing sodium intake lowers blood pressure and associated risks in many but not all normotensive individuals as well.
   21 CFR 101.74, Health claims: sodium and hypertension · checked 2026-09-24
6. amch-r1-06 · case-control study
   the crude odds ratio for daily intake of foods containing high levels of aluminium was 2.0 and, when adjusted for covariates, was 8.6 (P=0.19)...Adjusted odds ratios were also elevated for grain product desserts, American cheese, chocolate pudding or beverages, salt and chewing gum.
   Age Ageing, 1999 · checked 2026-09-24
7. amch-r1-02 · randomised controlled trial
   The first study was designed to determine the effect of 2 mo of daily consumption of vitamin D3-fortified (600 IU/d) process cheese on serum 25-hydroxyvitamin D (25-OHD), parathyroid hormone (PTH), and osteocalcin (OC) concentrations among 100 older (> or =60 yr) men and women...There were no differences in 25-OHD, PTH, or OC after 2 mo of fortified cheese intake.
   J Dairy Sci, 2005 · checked 2026-09-24