{"url":"https://whatshealthyandwhy.com/microwaving-food/is-microwaving-food-safe","path":"/microwaving-food/is-microwaving-food-safe","alternates":{"json":"https://whatshealthyandwhy.com/api/articles/microwaving-food/is-microwaving-food-safe.json","markdown":"https://whatshealthyandwhy.com/microwaving-food/is-microwaving-food-safe.md"},"topic":{"slug":"microwaving-food","name":"Microwaving Food","url":"https://whatshealthyandwhy.com/microwaving-food"},"slug":"is-microwaving-food-safe","order":1,"title":"Is Microwaving Food Safe?","question":"Does microwaving destroy nutrients or make food unsafe?","answer":"Microwaving is unlikely to make food unsafe and usually keeps nutrients as well as boiling; the real risks are uneven heating, hot spots and plastic.","description":"Microwave ovens use non-ionizing radiation. What studies show on nutrient loss, uneven heating, hot spots and containers, and when to use another method.","confidence":3,"confidenceNote":"Lab studies agree microwaving keeps most nutrients about as well as other methods and oven leakage is far below limits, but evidence is mostly small, with a few documented exceptions.","evidenceSummary":{"rctCount":0,"observationalCount":3,"metaAnalysisCount":0,"totalParticipants":"200+","replicated":true,"newestStudyYear":2023},"category":{"categoryTitle":"What's Harming You","categorySlug":"harming-you","subcategoryName":"Kitchen & Cookware","subcategorySlug":"kitchen","url":"https://whatshealthyandwhy.com/explore/harming-you/kitchen"},"actions":["Cook vegetables with a splash of water for the shortest tenderizing time: in broccoli, longer times and more water meant bigger losses of vitamin C, phenolics and glucosinolates [3][2].","Cover, stir or turn halfway, let food stand and check the middle is steaming hot: microwave heating is uneven, edges most [10]; frozen stuffed chicken must reach 165°F (74°C) [11].","Heat food in glass or ceramic, not plastic. Microwaving released the most micro- and nanoplastics of any storage or heating scenario in lab tests [6]."],"cautions":["Frozen breaded chicken that looks cooked, such as stuffed chicken, is raw inside. Follow the oven directions, because microwave cooking was a key factor in repeated Salmonella outbreaks [4][11].","Do not microwave breast milk or formula to hot: it cut anti-infective factors in human milk, E. coli growth rose 18-fold; children have been scalded taking hot items out [12][5]."],"simpleText":"Microwaving does not make food radioactive, and it usually keeps nutrients as well as other cooking methods. Oven leakage is far below safety limits [1], and vegetables keep their plant compounds about as well as when steamed and better than when boiled, especially with little water, though vitamin C is lost with any heat [2][3]. The real risks are practical: uneven heating that leaves raw spots, hot spots that scald, and heating food in plastic [4][5][6].","mediumText":"How it works\n\nWhat a microwave does. A microwave oven uses 2.45 GHz radio waves to heat the water in food. This is non-ionizing radiation: it warms food but does not make it radioactive. In a survey of 117 home and restaurant ovens, leakage at one metre ranged from 0.43 to 16.4 microwatts per square centimetre, all well under the 1 milliwatt per square centimetre limit recommended by ICNIRP, and it rose with oven age and power [1].\n\nNutrients: it depends on the food and the water. Vitamins and plant compounds are lost mostly by leaching into cooking water and by long heating, so methods that use little water and time do best [3]. In broccoli, vitamin C had the greatest losses from breakdown and leaching, while phenolics and glucosinolates were lost mainly by leaching, and the authors advised avoiding the longest times and largest water volumes [3]. In a comparison of boiling, microwaving and steaming of three brassica vegetables, boiling lowered most phytochemicals, microwaving kept glucosinolates well and preserved color best, and vitamin C was lost with every method [2]. In red cabbage, gentler settings kept the enzyme that activates glucosinolates, while a high-power setting destroyed it [7]. See sulforaphane.\n\nWhere microwaving loses. Microwaving beef, pork and milk destroyed about 30 to 40 percent of their vitamin B12, turning it into an inactive form, though that study did not compare other cooking methods [8]. In rats, 60 seconds of microwaving, like 45 minutes in an oven, blocked garlic's ability to inhibit carcinogen binding to DNA, unless crushed garlic stood for 10 minutes first [9]. See raw versus cooked garlic.\n\nThe real safety issues. Heating is uneven, with the edges heating most [10]. Raw, breaded, pre-browned chicken products caused four Salmonella outbreaks in Minnesota, where most patients thought the product was cooked and used a microwave [4]. In a 2022 U.S. survey, 29 percent of people who cooked such products used a microwave, and 8 percent of those used one rated 750 watts or less, which may not cook them through [11]. Hot contents can also scald: of 104 non-tap-water scald admissions in young children at one burn center, 9 involved a child opening a microwave and taking out a hot item [5].\n\nContainers. Microwaving plastic released far more particles than cold storage [6]. See plastic food containers.","deepText":"The evidence in detail\n\nRadiation. Lahham and Sharabati measured 117 ovens aged one month to over 20 years, with rated power of 1,000 to 1,600 watts. Average leakage at one metre was 3.64 microwatts per square centimetre, only about 6 percent of ovens leaked more than 10, and none approached the 1 milliwatt per square centimetre ICNIRP limit. Leakage correlated with age and power, more strongly with age, so older ovens leak most [1]. This is a survey in one region, but it fits the conclusion that ovens are not a radiation concern at normal distances.\n\nVegetables. López-Berenguer and colleagues varied time, power and water in broccoli. All the compounds studied fell, apart from minerals, which were stable. Vitamin C fell most and the longest time and largest water volume were worst. They noted that earlier reports on microwaving were \"controversial\" because conditions differed [3]. Pellegrini and colleagues compared four methods on fresh and frozen brassica vegetables. Boiling cut most phytochemicals, steaming released polyphenols, microwaving best preserved color and kept glucosinolates well, and vitamin C was lost in great amounts by all methods. Fresh vegetables retained phytochemicals and antioxidant capacity better than frozen ones [2]. Verkerk and Dekker heated red cabbage under different time and power settings: total glucosinolates were high under all settings and sometimes exceeded raw levels, probably because heating made them easier to extract. Active myrosinase survived 24 minutes at 180 W and 8 minutes at 540 W but was destroyed by 4.8 minutes at 900 W [7]. Taken together, microwaving is competitive for vegetables when it uses little water and time, but vitamin C losses are unavoidable with any heat.\n\nLosses and exceptions. Watanabe and colleagues found about 30 to 40 percent vitamin B12 loss in microwaved raw beef, pork and milk, due to degradation into products with no vitamin activity in a microbial assay and no toxicity in rats [8]. Song and Milner reported that in rats, as little as 60 seconds of microwave heating or 45 minutes of oven heating blocked garlic from inhibiting carcinogen binding to mammary DNA, and that a 10-minute stand after crushing preserved the effect. The losses were consistent with inactivation of the enzyme alliinase [9]. That is an animal model, not evidence about human cancer. Quan and colleagues microwaved 22 frozen human milk samples and, separately, 10 more for bacterial growth tests. Heating to 72 to 98°C sharply reduced lysozyme and IgA, and E. coli growth at 98°C or above was 18 times that in control milk. Even at 20 to 25°C growth was five times control, so the authors questioned safety at any temperature [12]. Samples were few and lab-based.\n\nPathogens and burns. Smith and colleagues traced four Minnesota outbreaks from 1998 to 2006 (33, 4, 27 and 3 cases) to raw, frozen, microwaveable, breaded, stuffed chicken. Most patients thought the product was precooked, most used a microwave, most did not follow the package, and none took its temperature. Label changes did not stop later outbreaks, and the authors advised against microwaving these products unless precooked or irradiated [4]. Marshall and colleagues' 2022 survey found 82.7 percent of respondents used an oven, 54 percent also used another appliance and 29 percent used a microwave. They suggested that producers sell the products fully cooked or control Salmonella upstream [11]. Lowell and colleagues reviewed 137 charts of children under five admitted with scalds over three years at a Chicago burn center; 104 were non-tap-water scalds and 9 followed a child removing a hot item from a microwave [5].\n\nWhat conflicts or is missing. The nutrient studies use different foods, powers and water volumes, so the same method can look good or bad. We found no trial comparing the health of people eating microwaved with conventionally cooked food. The garlic and B12 results are lab or animal findings and did not test whether the losses matter for diet as a whole.\n\nBottom line (moderate confidence). Microwaving is a safe way to heat food and, with little water and short times, a good one for vegetables. The documented problems are specific: B12 and a few heat-sensitive compounds, uneven heating of raw products, infant milk, scalds, and plastic containers.\n\nSwaps, ranked by evidence\n\n1. Microwave vegetables with a splash of water for the shortest time (consistent lab data). Losses came mainly from leaching and long times [3][2].\n2. Use glass or ceramic, not plastic (consistent lab data). [6]\n3. Use the oven, not the microwave, for frozen breaded or stuffed raw chicken (outbreak data). Cook to 165°F (74°C) [4][11].\n4. Warm infant milk gently in a bowl of warm water instead (lab and injury data). Hot microwaved milk lost anti-infective factors, and hot spots scald [12][5].\n5. Crush garlic and wait 10 minutes before any heating (animal data only). [9]","deepTruncated":false,"references":[{"id":"1","title":"Radiofrequency radiation leakage from microwave ovens","authors":"Lahham A, Sharabati A","year":2013,"journal":"Radiat Prot Dosimetry","pmid":"23861537","url":"https://pubmed.ncbi.nlm.nih.gov/23861537/"},{"id":"2","title":"Effect of different cooking methods on color, phytochemical concentration, and antioxidant capacity of raw and frozen brassica vegetables","authors":"Pellegrini N, Chiavaro E, Gardana C, et al.","year":2010,"journal":"J Agric Food Chem","pmid":"20218674","url":"https://pubmed.ncbi.nlm.nih.gov/20218674/"},{"id":"3","title":"Effects of microwave cooking conditions on bioactive compounds present in broccoli inflorescences","authors":"López-Berenguer C, Carvajal M, Moreno DA, et al.","year":2007,"journal":"J Agric Food Chem","pmid":"17979232","url":"https://pubmed.ncbi.nlm.nih.gov/17979232/"},{"id":"4","title":"Outbreaks of salmonellosis in Minnesota (1998 through 2006) associated with frozen, microwaveable, breaded, stuffed chicken products","authors":"Smith KE, Medus C, Meyer SD, et al.","year":2008,"journal":"J Food Prot","pmid":"18939771","url":"https://pubmed.ncbi.nlm.nih.gov/18939771/"},{"id":"5","title":"Preventing unintentional scald burns: moving beyond tap water","authors":"Lowell G, Quinlan K, Gottlieb LJ","year":2008,"journal":"Pediatrics","pmid":"18829804","url":"https://pubmed.ncbi.nlm.nih.gov/18829804/"},{"id":"6","title":"Assessing the Release of Microplastics and Nanoplastics from Plastic Containers and Reusable Food Pouches: Implications for Human Health","authors":"Hussain KA, Romanova S, Okur I, et al.","year":2023,"journal":"Environ Sci Technol","pmid":"37343248","url":"https://pubmed.ncbi.nlm.nih.gov/37343248/"},{"id":"7","title":"Glucosinolates and myrosinase activity in red cabbage (Brassica oleracea L. var. Capitata f. rubra DC.) after various microwave treatments","authors":"Verkerk R, Dekker M","year":2004,"journal":"J Agric Food Chem","pmid":"15563214","url":"https://pubmed.ncbi.nlm.nih.gov/15563214/"},{"id":"8","title":"Effects of Microwave Heating on the Loss of Vitamin B(12) in Foods","authors":"Watanabe F, Abe K, Fujita T, et al.","year":1998,"journal":"J Agric Food Chem","pmid":"10554220","url":"https://pubmed.ncbi.nlm.nih.gov/10554220/"},{"id":"9","title":"The influence of heating on the anticancer properties of garlic","authors":"Song K, Milner JA","year":2001,"journal":"J Nutr","pmid":"11238815","url":"https://pubmed.ncbi.nlm.nih.gov/11238815/"},{"id":"10","title":"Frequency Distribution in Domestic Microwave Ovens and Its Influence on Heating Pattern","authors":"Luan D, Wang Y, Tang J, et al.","year":2017,"journal":"J Food Sci","pmid":"27992653","url":"https://pubmed.ncbi.nlm.nih.gov/27992653/"},{"id":"11","title":"Appliances Used by Consumers to Prepare Frozen Stuffed Chicken Products - United States, May-July 2022","authors":"Marshall KE, Canning M, Ablan M, et al.","year":2022,"journal":"MMWR Morb Mortal Wkly Rep","pmid":"36454679","url":"https://pubmed.ncbi.nlm.nih.gov/36454679/"},{"id":"12","title":"Effects of microwave radiation on anti-infective factors in human milk","authors":"Quan R, Yang C, Rubinstein S, et al.","year":1992,"journal":"Pediatrics","pmid":"1557249","url":"https://pubmed.ncbi.nlm.nih.gov/1557249/"}],"wordCount":1261,"source":{"path":"src/content/topics/microwaving-food/is-microwaving-food-safe.md"},"citeAs":"“Does microwaving destroy nutrients or make food unsafe?.” What's Healthy and Why. https://whatshealthyandwhy.com/microwaving-food/is-microwaving-food-safe","notice":"General information backed by peer-reviewed research, not medical advice."}