Microwaving food - controversial area

[Guest guest]

Roger & Phil,

 

Thanks for the citations on the potential dangers of microwave

cooking. I will look into this further. This is the kind of evidence I

was asking for. Now, of course, to judge and assess that evidence.

 

Bob

 

, " "

< wrote:

>

> Hi Roger & All,

>

> Roger wrote:

> > Here are some references on potential hazards of microwave cooking

>

> I am wary of Mercola's website.

>

> In a Medline search, some papers say that microwaving foods does

> harm; others say the opposite; see below.

>

> I microwave some food but do not microwave food in plastic

> containers; I prefer to put the food on a glass or ceramic dish.

>

> Ghadirian P, Baillargeon J, Simard A, Perret C. Food habits and

> pancreatic cancer: a case-control study of the Francophone community

> in Montreal, Canada. Cancer Epidemiol Biomarkers Prev. 1995

> Dec;4(8):895-9. H0<0pital H0<0tel-Dieu de Montr¨¦al, Department

> of Nutrition, Faculty of Medicine, University of Montreal, Quebec,

> Canada. In a population-based case-control study of pancreatic cancer

> and nutrition among the Francophone population of Montreal (Quebec,

> Canada), a total of 179 cases and 239 controls matched for age, sex,

> and language (French) were interviewed between 1984 and 1988. Data on

> food habits, methods of food preparation and preservation, and

> related information were obtained through a questionnaire. The study

> found an increased risk of pancreatic cancer associated with a high

> consumption of salt [relative risk (RR) = 4.28; 95% confidence

> interval (CI) = 2.20-8.36], smoked meat (RR = 4.68; CI = 2.05-10.69),

> dehydrated food (RR = 3.10; 95% CI = 1.55-6.22), fried food (RR=

> 3.84; 95% CI = 1.74-8.48), and refined sugar (RR = 2.81; 95% CI =

> 0.94-8.45). An inverse association was found with the consumption of

> food with no preservatives or additives (RR = 0.08; 95% CI = 0.01-

> 0.59), raw food (RR = 0.28; 95% CI = 0.10-0.75), and food prepared by

> presto or high-pressure cooking (RR = 0.35% 95% CI = 0.15-0.81),

> electricity (RR = 0.30; 95% CI = 0.90), or microwave oven (RR = 0.56;

> 95% CI = 0.34-0.92). Cooking with firewood was associated with a

> significantly higher risk for pancreatic cancer (RR = 4.63; 95% CI =

> 1.15-16.52). The results of this study suggest that food habits may

> play an important role in the etiology of cancer of the pancreas

> among French Canadians in Montreal, whereas other food habits may

> reduce the risk of this disease. PMID: 8634663 [PubMed - indexed for

> MEDLINE]

>

> Taghavi N, Yazdi I. Type of food and risk of oral cancer. Arch Iran

> Med. 2007 Apr;10(2):227-32. Department of Oral Pathology, Shaheed

> Beheshti University of Medical Sciences, Tehran, Iran. Cancer is

> the eventual outcome of the interaction between genetic factors and

> environmental exposures. Nutrition and diet, as environmental factors

> and determinants of growth and body composition can contribute to the

> risk of some human cancers such as oral cancer. This article explains

> the ways of carcinogenesis and the effect of diet on this process,

> especially focusing on head, neck, and oral cancers. To reduce the

> risk of oral and pharyngeal cancer, especially squamous cell

> carcinoma, the most common oral cancer, diet must be optimized,

> primarily to reduce calorie intake, monounsaturated fat, and red or

> processed meat. Consumption of fruits, vegetables, and cereals, which

> are the major source of vitamins and fiber, should be adequate in the

> daily diet. Optimal levels of daily allowance of micronutrients like

> vitamin C, E, antioxidants, zinc, beta-carotene, and folate are

> effective in prevention of oral cancer. Consumption of fried or

> broiled foods and employment of microwave cooking, because of

> formation of heterocyclic amines, must be avoided because of

> increasing risks of oral cancer including the salivary gland tumors.

> PMID: 17367228 [PubMed - indexed for MEDLINE]

>

> Sugimura T, Wakabayashi K, Nakagama H, Nagao M. Heterocyclic amines:

> Mutagens/carcinogens produced during cooking of meat and fish. Cancer

> Sci. 2004 Apr;95(4):290-9. National Cancer Center, Chuo-ku, Tokyo 104-

> 0045, Japan. tsugimur Research leading to the

> discovery of a series of mutagenic and carcinogenic heterocyclic

> amines (HCAs) was inspired by the idea that smoke produced during

> cooking of food, especially meat or fish, might be carcinogenic. More

> than ten kinds of HCAs, actually produced by cooking or heating of

> meat or fish, have now been isolated and their structures determined,

> most being previously unregistered compounds. They are highly

> mutagenic towards Salmonella typhimurium in the presence of S9 mix

> and are also mutagenic in vitro and in vivo toward mammalian cells.

> HCAs have now been chemically synthesized in quantity and subjected

> to long-term animal testing. When HCAs were fed in the diet, rodents

> developed cancers in many organs, including the colon, breast and

> prostate, and one HCA produced hepatomas in monkeys. The lesions

> exhibited alteration in genes including Apc, beta-catenin and Ha-ras,

> and these changes provide clues to the induction mechanisms. The HCAs

> are oxidized to hydroxyamino derivatives by cytochrome P450s, and

> further converted to ester forms by acetyltransferase and

> sulfotransferase. Eventually, they produce DNA adducts through the

> formation of N-C bonds at guanine bases. There are HCA-sensitive and

> resistant strains of rodents and a search for the responsible genes

> is now under way. While the content of HCAs in dishes consumed in

> ordinary life is low and not sufficient in itself to explain human

> cancer, the coexistence of many other mutagens/carcinogens of either

> autobiotic or xenobiotic type and the possibility that HCAs induce

> genomic instability and heightened sensitivity to tumor promoters

> suggest that avoidance of exposure to HCAs or reduction of HCAs'

> biological effects as far as possible are to be highly recommended.

> Usage of microwave ovens for cooking and supplementation of the diet,

> for example with soy-isoflavones, which have been found to suppress

> the occurrence of HCA-induced breast cancers, should be encouraged.

> Advice to the general public about how to reduce the carcinogenic

> load imposed by HCAs would be an important contribution to cancer

> prevention. PMID: 15072585 [PubMed - indexed for MEDLINE]

>

> Yuan Y, Chen F, Zhao GH, Liu J, Zhang HX, Hu XS. A comparative

> study of acrylamide formation induced by microwave and conventional

> heating methods. J Food Sci. 2007 May;72(4):C212-6. College of

> Food Science & Nutritional Engineering, China Agricultural Univ.,

> Beijing, 100083, China. In this study, the formation of acrylamide

> upon treatment with microwave and conventional heating, boiling, or

> frying was investigated in both Asn/Fru and Asn/Glc model systems and

> in potato chips. Acrylamide levels were analyzed by HPLC method,

> which was confirmed by HPLC-MS/MS. Present results in model systems

> showed that pH value had a complex influence on the formation of

> acrylamide in the 2 systems during both microwaving (600 W) and

> boiling (120 +/- 1 degrees C). At pH < 8.0, acrylamide content

> increased with increasing the pH value, reaching the maximum at pH

> 8.0 whereas acrylamide content decreased with the increase of pH.

> Regardless of pH and heating methods, acrylamide content generally

> increased with increasing treatment time. Surprisingly, all present

> results showed that microwave heating not only induced acrylamide

> formation in the 2 model systems but also facilitated more acrylamide

> to be formed as compared to the boiling method at identical pH and

> treatment time. At pH 4.0, 8.0, and 10.0, the larger the microwave

> power, the more the acrylamide content. Consistent with the above

> observation, treatment of potato chips with microwave heating for 2.5

> to 3.5 min in the range 550 to 750 W similarly resulted in acrylamide

> formation. The highest acrylamide content was formed by 750 W

> microwave treatment as 0.897 +/- 0.099 mg/kg, which was significantly

> higher than that produced by traditional frying (180 +/- 1 degrees

> C), 0.645 +/- 0.035 mg/kg (P < 0.05). PMID: 17995763 [PubMed -

> indexed for MEDLINE

>

> Best regards,

>

>

[Guest guest]

Hi Roger & All,

 

Roger wrote:

> Here are some references on potential hazards of microwave cooking

 

I am wary of Mercola's website.

 

In a Medline search, some papers say that microwaving foods does

harm; others say the opposite; see below.

 

I microwave some food but do not microwave food in plastic

containers; I prefer to put the food on a glass or ceramic dish.

 

Ghadirian P, Baillargeon J, Simard A, Perret C. Food habits and

pancreatic cancer: a case-control study of the Francophone community

in Montreal, Canada. Cancer Epidemiol Biomarkers Prev. 1995

Dec;4(8):895-9. H0<0pital H0<0tel-Dieu de Montr¨¦al, Department

of Nutrition, Faculty of Medicine, University of Montreal, Quebec,

Canada. In a population-based case-control study of pancreatic cancer

and nutrition among the Francophone population of Montreal (Quebec,

Canada), a total of 179 cases and 239 controls matched for age, sex,

and language (French) were interviewed between 1984 and 1988. Data on

food habits, methods of food preparation and preservation, and

related information were obtained through a questionnaire. The study

found an increased risk of pancreatic cancer associated with a high

consumption of salt [relative risk (RR) = 4.28; 95% confidence

interval (CI) = 2.20-8.36], smoked meat (RR = 4.68; CI = 2.05-10.69),

dehydrated food (RR = 3.10; 95% CI = 1.55-6.22), fried food (RR=

3.84; 95% CI = 1.74-8.48), and refined sugar (RR = 2.81; 95% CI =

0.94-8.45). An inverse association was found with the consumption of

food with no preservatives or additives (RR = 0.08; 95% CI = 0.01-

0.59), raw food (RR = 0.28; 95% CI = 0.10-0.75), and food prepared by

presto or high-pressure cooking (RR = 0.35% 95% CI = 0.15-0.81),

electricity (RR = 0.30; 95% CI = 0.90), or microwave oven (RR = 0.56;

95% CI = 0.34-0.92). Cooking with firewood was associated with a

significantly higher risk for pancreatic cancer (RR = 4.63; 95% CI =

1.15-16.52). The results of this study suggest that food habits may

play an important role in the etiology of cancer of the pancreas

among French Canadians in Montreal, whereas other food habits may

reduce the risk of this disease. PMID: 8634663 [PubMed - indexed for

MEDLINE]

 

Taghavi N, Yazdi I. Type of food and risk of oral cancer. Arch Iran

Med. 2007 Apr;10(2):227-32. Department of Oral Pathology, Shaheed

Beheshti University of Medical Sciences, Tehran, Iran. Cancer is

the eventual outcome of the interaction between genetic factors and

environmental exposures. Nutrition and diet, as environmental factors

and determinants of growth and body composition can contribute to the

risk of some human cancers such as oral cancer. This article explains

the ways of carcinogenesis and the effect of diet on this process,

especially focusing on head, neck, and oral cancers. To reduce the

risk of oral and pharyngeal cancer, especially squamous cell

carcinoma, the most common oral cancer, diet must be optimized,

primarily to reduce calorie intake, monounsaturated fat, and red or

processed meat. Consumption of fruits, vegetables, and cereals, which

are the major source of vitamins and fiber, should be adequate in the

daily diet. Optimal levels of daily allowance of micronutrients like

vitamin C, E, antioxidants, zinc, beta-carotene, and folate are

effective in prevention of oral cancer. Consumption of fried or

broiled foods and employment of microwave cooking, because of

formation of heterocyclic amines, must be avoided because of

increasing risks of oral cancer including the salivary gland tumors.

PMID: 17367228 [PubMed - indexed for MEDLINE]

 

Sugimura T, Wakabayashi K, Nakagama H, Nagao M. Heterocyclic amines:

Mutagens/carcinogens produced during cooking of meat and fish. Cancer

Sci. 2004 Apr;95(4):290-9. National Cancer Center, Chuo-ku, Tokyo 104-

0045, Japan. tsugimur Research leading to the

discovery of a series of mutagenic and carcinogenic heterocyclic

amines (HCAs) was inspired by the idea that smoke produced during

cooking of food, especially meat or fish, might be carcinogenic. More

than ten kinds of HCAs, actually produced by cooking or heating of

meat or fish, have now been isolated and their structures determined,

most being previously unregistered compounds. They are highly

mutagenic towards Salmonella typhimurium in the presence of S9 mix

and are also mutagenic in vitro and in vivo toward mammalian cells.

HCAs have now been chemically synthesized in quantity and subjected

to long-term animal testing. When HCAs were fed in the diet, rodents

developed cancers in many organs, including the colon, breast and

prostate, and one HCA produced hepatomas in monkeys. The lesions

exhibited alteration in genes including Apc, beta-catenin and Ha-ras,

and these changes provide clues to the induction mechanisms. The HCAs

are oxidized to hydroxyamino derivatives by cytochrome P450s, and

further converted to ester forms by acetyltransferase and

sulfotransferase. Eventually, they produce DNA adducts through the

formation of N-C bonds at guanine bases. There are HCA-sensitive and

resistant strains of rodents and a search for the responsible genes

is now under way. While the content of HCAs in dishes consumed in

ordinary life is low and not sufficient in itself to explain human

cancer, the coexistence of many other mutagens/carcinogens of either

autobiotic or xenobiotic type and the possibility that HCAs induce

genomic instability and heightened sensitivity to tumor promoters

suggest that avoidance of exposure to HCAs or reduction of HCAs'

biological effects as far as possible are to be highly recommended.

Usage of microwave ovens for cooking and supplementation of the diet,

for example with soy-isoflavones, which have been found to suppress

the occurrence of HCA-induced breast cancers, should be encouraged.

Advice to the general public about how to reduce the carcinogenic

load imposed by HCAs would be an important contribution to cancer

prevention. PMID: 15072585 [PubMed - indexed for MEDLINE]

 

Yuan Y, Chen F, Zhao GH, Liu J, Zhang HX, Hu XS. A comparative

study of acrylamide formation induced by microwave and conventional

heating methods. J Food Sci. 2007 May;72(4):C212-6. College of

Food Science & Nutritional Engineering, China Agricultural Univ.,

Beijing, 100083, China. In this study, the formation of acrylamide

upon treatment with microwave and conventional heating, boiling, or

frying was investigated in both Asn/Fru and Asn/Glc model systems and

in potato chips. Acrylamide levels were analyzed by HPLC method,

which was confirmed by HPLC-MS/MS. Present results in model systems

showed that pH value had a complex influence on the formation of

acrylamide in the 2 systems during both microwaving (600 W) and

boiling (120 +/- 1 degrees C). At pH < 8.0, acrylamide content

increased with increasing the pH value, reaching the maximum at pH

8.0 whereas acrylamide content decreased with the increase of pH.

Regardless of pH and heating methods, acrylamide content generally

increased with increasing treatment time. Surprisingly, all present

results showed that microwave heating not only induced acrylamide

formation in the 2 model systems but also facilitated more acrylamide

to be formed as compared to the boiling method at identical pH and

treatment time. At pH 4.0, 8.0, and 10.0, the larger the microwave

power, the more the acrylamide content. Consistent with the above

observation, treatment of potato chips with microwave heating for 2.5

to 3.5 min in the range 550 to 750 W similarly resulted in acrylamide

formation. The highest acrylamide content was formed by 750 W

microwave treatment as 0.897 +/- 0.099 mg/kg, which was significantly

higher than that produced by traditional frying (180 +/- 1 degrees

C), 0.645 +/- 0.035 mg/kg (P < 0.05). PMID: 17995763 [PubMed -

indexed for MEDLINE

 

Best regards,