Table 5.

Summary of dietary factors associated with nasopharyngeal carcinoma

Potential risk factor	Summary of results
Alcohol	Risk factor [78] [S1,S2]
	Potentially associated [79] [S3]
	No overall association [56,58-73]
	Results inconclusive [S4]
	Result undocumented [S5]
Dairy:
Rancid dairy products	Rancid butter risk factor [61,75]
	Rancid butter potential association[91]
Other dairy products	Milk protective [S5,S6]
	Milk no association [61,86]
	Butter no association [61]
	Eggs protective [61] [S6]
	Eggs no association [86]
	Salted (duck) eggs (particular time points) risk factor [79,83]
	No association [91]
Fish and shellfish:
Salted fish	Risk factor [57,59,64,65,71,77-82]
	Inconclusive [83-85]
	No association [59,71,76,85-88]
Other preserved fish	Protective [75]
	Dried fish results inconclusive [83]
	No association [87]
	Fermented fish (sauce) – no association [60,72,84]
Other fish/shellfish	Shrimp protective [79]
	No association [87]
	Fresh fish protective [S6]
	Fresh fish potentially protective [86]
	Fresh fish and other seafood – no association [86]
	Deep sea fish protective [S5]
Meat:
Smoked, cured, dried, salted preserved meat	Risk factor [58] [S1]
	Risk factor, but not consistent [75,82]
	No association [74,76,86-88]
	Quaddid risk factor [S7]
	Fermented pork no association [72]
	Salted meat no association [72]
Other meat	Fresh meat (pork/beef liver) risk factor [79]
	Red meat risk factor [68]
	Chicken risk factor [S7]
	Chicken protective [91]
	Fried meat – inconclusive association [61]
	Sheep’s tail fat no association [S7]
	Merguez, khelli no association [75]
	Fresh meat no association [86]
	Processed meat no association [S6]
	Sausage no association [72]
Other salted products	Salt-cured food risk factor [68]
	Salted vegetables risk factor (at least in adulthood) [79,82]
	Salted and dried tomatoes or salted or brined peppers risk factor [61]
	Other salty foods – inconclusive association [61]
	Salted vegetables no association [71]
	Salted mustard greens – inconclusive association [83]
	Salted roots no association [79]
Other fermented and preserved foods	Fermented pastes risk factor[89]
	Fermented black bean paste and fermented soy bean paste no association[83]
	Fermented foods no association [S1]
	Fermented soy bean products associated [92]
	Fermented soybean products no association [88]
	Fermented and salted vegetables no association [72]
	Preserved vegetables (potential) risk factor [57,65,72]
	Preserved plums risk factor[84,93]
	Preserved vegetables generally risk factor (although salted vegetables and picked Chinese cabbage protective) [93]
	Preserved vegetables no association [86,88]
	Preserved fruit no association [79]
	Pickled vegetables (and fungus on pickles) risk factor [S7]
	Mouldy bean curd no association[84]
Vegetables, beans and fruit	Chung choi not consistently associated, could be risk factor [77]
	Fresh fruits in childhood protective [81]
	Fresh fruit associated protective [61]
	Fresh fruit and vegetables protective [79]
	Fresh green vegetables protective, others no association [84]
	Fruit and vegetables protective [68] [S6]
	Leafy vegetables protective [85]
	Dark vegetables and fresh fruit protective [S5]
	Grapes protective[91,93]
	Non-preserved fruits and vegetables generally protective [93]
	Cooked vegetables and citrus fruits not consistently associated[75]
	Fresh fruit and vegetables (including green and leafy) no association [74,86]
	Servings per week of fruit and vegetables no association [88]
	Carrots no association[64,66,91]
Other:
Coffee	No association [73,86] [S6]
Tea	Herbal tea risk factor [85]
	Green tea protective [86]
	Herbal tea protective [82]
	Protective [65,73] [S4,S6]
	Inconclusive association [61]
	Black, Oolong tea no association [86]
Slow cooked soup	Protective [65,82]
Dietary nutrients	Folate, vitamin B6, protective; vitamin B12, methionine no association [S8]
	Vitamin A, Vitamin C, tocopherol no association [86]
	Beta carotene and vitamin C no association [74]
Foods containing nitrosamines	Inconclusive association across all foods [88]
Preserves and condiments	In childhood risk factor [S7]
	Regular spicy sauce consumption generally risk factor [61]
	No association [75,91]
Other	Irregular meals risk factor [61]
	Adult diet on weaning risk factor [S7]
	Rancid sheep fat risk factor [75]
	Melon seeds risk factor [85]
	Sugary, dried or salted snacks, risk factor [61]
	Food additives risk factor [S9]
	White bread risk factor [S9]
	Lentils protective [91]
	Corn bread protective [S9]
	Margarine and olive oil protective [S9]
	M’hammas no association [S7]
	Potatoes no association [91]
	Grains no association [61]
	Monosodium glutamate no association [85]
	Non-dairy oils and fats no association, unless salted [61]
	Olives no association [75,87]
	Protein, fat, carbohydrate, sodium intake, soybean milk no association [86]
	Olives inconclusive [61]
	French fries – inconclusive association [61]
	General diet – results unclear [95]

*References marked with letter S are available in the Online Supplementary Document.