--- topic: "Dairy" title: "Is Dairy Healthy?" order: 1 description: "What large studies say about milk, yogurt and cheese: heart disease, diabetes, bones, cancer, lactose and A2 milk, and how much is a sensible amount." question: "Is dairy healthy, or should you skip it?" answer: "Dairy likely does no harm for most people, and fermented types like yogurt and cheese look best; skip it only if it upsets you." actions: - "If you enjoy dairy, lean on plain yogurt and cheese, keep to about 1 to 2 servings a day, and go easy on sweetened dairy desserts [2][5][6]." - "If milk causes gas or loose stools, try smaller amounts before cutting it out: most people with lactose problems tolerate 12–15 g of lactose, about a cup of milk [7]." - "If you drop dairy, plan your calcium and vitamin D from other foods, because people who avoid dairy over lactose worries often fall short [8]." cautions: - "Milk allergy is different from lactose intolerance. Hives, wheezing, vomiting or swelling after dairy needs medical care and strict avoidance, not a smaller serving." - "Women drinking three or more glasses of milk daily had higher death rates in one large Swedish study; it was observational, possibly reflecting other factors, but argues against more-is-better [3]." - "Men with prostate cancer or strong family history can discuss high milk intake with their doctor, because milk nudges up IGF-I, a growth signal linked to prostate cancer risk [9]." confidence: 3 confidenceNote: "Large cohorts and meta-analyses mostly show neutral to mildly favorable links, but they are observational, results differ by dairy type, and no long trials cover heart attacks, fractures or cancer." evidenceSummary: rctCount: 0 observationalCount: 4 metaAnalysisCount: 7 totalParticipants: "938,000+ (pooled cohorts)" replicated: true newestStudyYear: 2022 references: - id: "1" pmid: "28374228" title: "Milk and dairy consumption and risk of cardiovascular diseases and all-cause mortality: dose-response meta-analysis of prospective cohort studies" authors: "Guo J, Astrup A, Lovegrove JA, et al." year: 2017 journal: "Eur J Epidemiol" - id: "2" pmid: "30217460" title: "Association of dairy intake with cardiovascular disease and mortality in 21 countries from five continents (PURE): a prospective cohort study" authors: "Dehghan M, Mente A, Rangarajan S, et al." year: 2018 journal: "Lancet" - id: "3" pmid: "25352269" title: "Milk intake and risk of mortality and fractures in women and men: cohort studies" authors: "Michaëlsson K, Wolk A, Langenskiöld S, et al." year: 2014 journal: "BMJ" - id: "4" pmid: "29537719" title: "Lactase persistence, milk intake, hip fracture and bone mineral density: a study of 97 811 Danish individuals and a meta-analysis" authors: "Bergholdt HKM, Larsen MK, Varbo A, et al." year: 2018 journal: "J Intern Med" - id: "5" pmid: "26912494" title: "Consumption of dairy foods and diabetes incidence: a dose-response meta-analysis of observational studies" authors: "Gijsbers L, Ding EL, Malik VS, et al." year: 2016 journal: "Am J Clin Nutr" - id: "6" pmid: "35041764" title: "Dairy product consumption and risk of cancer: A short report from the NutriNet-Santé prospective cohort study" authors: "Deschasaux-Tanguy M, Barrubés Piñol L, Sellem L, et al." year: 2022 journal: "Int J Cancer" - id: "7" pmid: "20404262" title: "Systematic review: effective management strategies for lactose intolerance" authors: "Shaukat A, Levitt MD, Taylor BC, et al." year: 2010 journal: "Ann Intern Med" - id: "8" pmid: "20186234" title: "NIH consensus development conference statement: Lactose intolerance and health" authors: "Suchy FJ, Brannon PM, Carpenter TO, et al." year: 2010 journal: "NIH Consens State Sci Statements" - id: "9" pmid: "28361446" title: "Does milk intake promote prostate cancer initiation or progression via effects on insulin-like growth factors (IGFs)? A systematic review and meta-analysis" authors: "Harrison S, Lennon R, Holly J, et al." year: 2017 journal: "Cancer Causes Control" - id: "10" pmid: "33446728" title: "Intake of dairy products and associations with major atherosclerotic cardiovascular diseases: a systematic review and meta-analysis of cohort studies" authors: "Jakobsen MU, Trolle E, Outzen M, et al." year: 2021 journal: "Sci Rep" - id: "11" pmid: "30722004" title: "Milk A1 β-casein and health-related outcomes in humans: a systematic review" authors: "Küllenberg de Gaudry D, Lohner S, Schmucker C, et al." year: 2019 journal: "Nutr Rev" - id: "12" pmid: "26878105" title: "Higher PUFA and n-3 PUFA, conjugated linoleic acid, α-tocopherol and iron, but lower iodine and selenium concentrations in organic milk: a systematic literature review and meta- and redundancy analyses" authors: "Średnicka-Tober D, Barański M, Seal CJ, et al." year: 2016 journal: "Br J Nutr" --- For most people, dairy is neither a health food nor a hazard. A pooled analysis of 29 cohort studies found no link between total dairy or milk and heart disease or early death, and fermented dairy such as cheese looked marginally better [1]. A 21-country study even found lower risks in people who ate more [2]. Dairy does not clearly protect bones [3][4]. Skip it if it upsets you, but replace the calcium. ## How it works Dairy is a package of protein, fat, calcium and milk sugar (lactose). People who avoid dairy over real or suspected lactose intolerance often take in too little calcium and vitamin D, which is the main nutritional cost of skipping it [8]. **Type matters more than the word "dairy."** In the pooled cohorts, plain milk and total dairy were neutral for heart disease and death, while fermented dairy (yogurt, cheese, sour milk) showed a small advantage [1]. Full-fat milk was linked to slightly more heart disease, and cheese to slightly less [10]. Yogurt, at about 80 g a day (a third of a cup), was linked to lower type 2 diabetes risk, with no extra benefit from eating more [5]. Butter showed no clear link either way in the 21-country PURE study [2]. Sweetened dairy desserts are a different food from plain yogurt, and one French cohort tied them to more bowel cancer [6]. **Lactose.** Lactose is the sugar in milk, and many adults make less of the enzyme (lactase) that digests it. That is not the same as being intolerant: most people who malabsorb lactose have no symptoms, and many who think they are intolerant do not malabsorb it [8]. A review of 36 randomized trials found that most people with presumed lactose intolerance tolerate 12 to 15 g of lactose, about a cup of milk [7]. **A1 and A2 milk.** Ordinary milk contains two kinds of beta-casein protein, A1 and A2. A2-only milk is sold as gentler. A systematic review of 15 randomized trials plus other studies rated certainty as moderate that A1 milk causes more digestive discomfort, and low or very low for every other health outcome [11]. A2 milk still contains lactose. **IGF-I.** Milk and dairy protein raise IGF-I (a growth hormone signal) slightly, and higher IGF-I is linked to prostate cancer risk. The size of the effect is small [9]. **Grass-fed and organic.** Organic milk, which comes from cows eating more pasture, has about 56% more omega-3 fats than conventional milk, but less iodine and selenium [12]. It is a modest upgrade, not a different food. Related reading: [yogurt](/yogurt/probiotics-bone-and-metabolic-health), [kefir](/kefir/gut-bone-and-immune-health), [raw milk](/raw-milk/the-raw-milk-debate) and [ghee](/ghee/clarified-butter-and-health). ## The evidence in detail **Heart disease and death.** Guo and colleagues pooled 29 prospective cohorts (938,465 people, 93,158 deaths) and found no association of total dairy or milk with mortality, coronary disease or cardiovascular disease. Fermented dairy was inversely linked, with a risk ratio of 0.98 per 20 g a day for both death and cardiovascular disease, and cheese 0.98 per 10 g a day for cardiovascular disease. Those small signals shrank when one large Swedish study was removed, and heterogeneity was very high. Several authors disclosed funding from dairy industry bodies [1]. The PURE cohort followed 136,384 adults aged 35 to 70 in 21 countries for about 9 years. Compared with no dairy, more than 2 servings a day went with lower total mortality (hazard ratio 0.83), major cardiovascular disease (0.78) and stroke (0.66), but not heart attack (0.89, not significant). Milk and yogurt showed lower risk, cheese did not reach significance, and butter showed none [2]. A 2021 meta-analysis found high-fat milk slightly worse (risk ratio 1.08 per 200 g a day for coronary disease) and cheese slightly better (0.96 per 20 g a day), again with heterogeneity [10]. **Diabetes.** In 22 cohorts (579,832 people, 43,118 cases), total dairy carried a risk ratio of 0.97 per 200 g a day and yogurt 0.86 at 80 g a day, flattening beyond that [5]. **Bones, and where the data disagree.** Two Swedish cohorts (61,433 women followed 20 years, 45,339 men followed 11) found that three or more glasses of milk a day in women went with a mortality hazard ratio of 1.93, and each glass with a 9% higher hip fracture risk. Markers of oxidative stress and inflammation were higher in milk drinkers. The authors warned about reverse causation and confounding [3]. A genetic design avoids much of that problem: among 97,811 Danes, lifelong lactase persistence, which raises milk intake, did not change hip fracture risk (hazard ratio 1.01), and pooling with five other Northern European studies found no fracture benefit, though femoral neck bone density was slightly higher [4]. Taken together, neither cohorts nor genetics show milk preventing fractures, while PURE found the opposite pattern for mortality. **Cancer.** A systematic review of 172 studies found that milk raises IGF-I modestly (0.10 standard deviations per standard deviation of milk intake) and that each standard deviation of IGF-I carried an odds ratio of 1.09 for prostate cancer [9]. In NutriNet-Santé (101,279 adults, 2,503 cancers over about six years), total dairy was unrelated to overall, breast, prostate or colorectal cancer. Two subtypes, fromage blanc and sugary dairy desserts, were linked to colorectal cancer, which the authors said warrants further investigation [6]. **Lactose and A2.** A review of 36 randomized trials found most adults tolerate 12 to 15 g of lactose, and evidence that near-zero-lactose milk beats that amount was insufficient [7]. An NIH panel concluded true prevalence of lactose intolerance is unknown and most people do not need to eliminate dairy completely [8]. For A1 versus A2, most trials measured intermediate markers and found no difference, yet pooled certainty was moderate for digestive symptoms [11]. **Organic milk.** A meta-analysis of 170 studies found organic milk higher in omega-3 fats (56%), conjugated linoleic acid (41%) and iron, and lower in iodine and selenium, with differences driven by grazing [12]. **Conflicts.** PURE and the Swedish cohorts disagree, and the fermented-dairy advantage depends on one study. No long trial has tested dairy against heart attacks, fractures or cancer. **Bottom line (confidence 3 of 5).** Dairy is optional. Large studies find it neutral to mildly favorable, especially yogurt and cheese, and do not show that it builds stronger bones.