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Food Science/daily spinach consumption


SPINACH, cooked, canned. According to Wikipedia and elsewhere, spinach has some excellent anti-cancer ingredients but also some negatives. I don't have any health issues at present related to the negatives, though I think my late mother had a kidney stone once in her old age. My question is have you seen any reports on how much cooked spinach is safe to eat daily. I saw one study in which the participants ate 20 grams a day and at the end of which they shows an increase in protective eye pigment. Twenty grams is not much considering one of those small, single-serving cans has 220 grams of spinach. I could eat a small can of spinach a day or every other day, but I can't find any data on safe daily consumption amounts. Ever come across this info or do you have any online links you can point me to; I searched, couldn't find any because of the raw spinach problems dominating search results.

Hi Jim,

My apologies for the length of time it has taken me to answer your question.

I thought there wouldn't be any controversy answering this as I had all of the information ready for you from previous experience, but!!! When I decided to ensure I was up-to-date I ran into some of the problems you noted in your question and others about the basic knowledge I had about spinach...

The big problem with spinach (and a number of other foods such as buckwheat, parsley, black pepper, cocoa, rhubarb, chard, beets, banana, poppy seed, chocolate, most nuts) is that they are high in oxalic acid and/or oxalates of calcium and iron. Baby spinach has less oxalic acid than the larger leafy green spinach that Popeye eats.  Less oxalic acid gives baby spinach a sweeter flavor.

While spinach is high in iron and calcium it is hard for the body to absorb because it is bound as an oxalate.  There are warnings for people with rheumatoid arthritis and kidney stones to avoid spinach and other foods that contain oxalic acid or its compounds.  Most kidney stones are composed of calcium oxalate.  Also unbound oxalic acid in spinach will interfere with calcium and iron absorption.

As a result of your question and my new readings I will cut down on my consumption of spinach while this controversy plays out.  There is no final word, just preliminary studies needing peer review and follow-up.  
There are studies showing increased kidney stone formation in lab animals when oxalic acid or calcium oxalates are added to their diets, and studies that show no relation.  

Regarding your question, I would recommend a 3 ounce serving (raw baby spinach) no more than twice a week for healthy people and NO SPINACH for those already afflicted with kidney stones and/or rheumatoid arthritis.  I do eat some canned products, but not spinach. Canned products have their own set of problems with BPA (hormone-like substance). I first try to find the products I need in a glass container, thank the company for using glass and for their product and tell my friends... trying to promote healthier, more sustainable and less contaminating life-choices.

As always a variety of fruits and vegetables will ensure that you are getting a better balance of nutrition (including flavinoids and enzymes). while avoiding a heavy dose of anything that might be bad in a food (if consumed exclusively or in large quantities)  "Color your plate" as the saying goes... Spinach contains 13+ different flavinoids and C and beta carotene, so it's high antioxidant content places it on a desireable food source list, but the oxalic acid content should, for the moment, temper your consumption.

As always I recommend organic sources for your foods as the only way to avoid genetically engineered foods (both plant and animal), minimal cooking and no processed foods.  But I recognize that it is difficult to avoid some of those snacks we have become so accustomed to over the years!!!

I hope I was able to help,
Please ask follow-up questions for anything you want clarification on,
Michael Polidori  

Food Science

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Michael Polidori


I can answer questions about food safety issues and benefits vs risks issues related to the growing, environmental effects and health effects of conventional, organic and gene altered food (GE GMO genetically engineered), both plants and animals. I can answer questions related to the cause and treatment of nutritionally related disease (including immune related diseases) and nutritional problems related to healing physiological or nutritional injuries.


I have been studying food growing methods, regulatory rules and organic/conventional/biotechnological methods of producing foods since 1998. I have prepared materials for distribution concerning health safety issues, lack of regulation, environmental dangers and industry sponsored research of genetically engineered plants and animals. I have also created similar materials promoting the benefits of organic agriculture for not only direct health benefits but for dramatic reductions in pollution, indirectly benefitting our health. I have prepared research materials for and participated in Public Television talk and radio shows regarding the issues surrounding genetic engineering and organic foods and debated in college forums with mainstream scientific experts about the safety & regulatory issues of gene altered foods. 2000-2002 I managed booths at major North Carolina events interfacing with the public (including farmers) on organic vs GMO benefits and dangers. I understand regulatory practices, shortcomings & revolving jobs doors of the FDA, USDA and EPA and the industries they regulate. I have been involved in nutrition, health care, prescription drug, vaccine, disease, immune and wellness issues since 1997 reading and writing on the internet and in practical applications with myself, family and friends leading to paths of health, wellness and fitness.

North Carolina Citizens For Safe Food, Public Citizen, Organic Consumers Association, Union of Concerned Scientists, Environmental Working Group, PSRAST.

No Degree, but some college in the sciences (Biology, Chemistry, Calculus, Astronomy and Physics). I have also taken several courses in Logic and Philosophy. I am involved in extensive research using mainstream websites (many of which I am on mailing lists for) such as - peer-reviewed publications (The Lancet, New England Journal of Medicine, others), PubMed database of research studies, National Institutes of Health, FDA, USDA, EPA, University Research libraries, hospital databases (John Hopkins, Mayo Clinic, Cleveland Clinic, others). I also regulary contact/correspond-with manufacturers/suppliers of food products, pharmaceuticals (including vaccines) and supplements with questions, recommendations, criticisms and complements. Every week, I learn something new!

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