Home » Community Life, Elizabeth Paratz, Recent Posts

The milchig-fleishig quandary and other Jewish and gastronomic medical observations

October 29, 2009 – 5:46 pm7 Comments

Image source: pratie.blogspot.com

This article is the second in a series on the medical benefits (or otherwise) of Jewish food, culture, and religion. In this series, Liz Paratz peruses the medical literature for evidence-based answers to the big question: Being Jewish – is it good for the Jews? This is the second and final instalment on Jewish food.

Keeping Milk and Meat Separate (Milchig and Fleishig)

Personally, I didn’t expect to find that much hard data on the laws of milchig and fleishig when I started running search terms through PubMed, so this was probably the most surprising set of results of all.

Essentially, there’s good news and there’s bad news. I’ll start with the good news –

It’s definitely good to separate meat meals from milk meals : In articles such as ‘Inhibition of haem-iron absorption in man by calcium’ (1992), and replicated in other studies since, Swedish researchers found that calcium blocks the absorption of iron in your gut – so it kind of defeats the purpose of eating the meat in the first place. This is basic physiology, but the degree to which the blocking was found to occur is what really amazed me. The researchers fed subjects either plain hamburgers or hamburgers with calcium, and discovered that when calcium was present, iron absorption was decreased by 41%. In other words, you only get a little over half the nutritional value from your meat if there’s a slice of cheese lying on top of it.

And so, the authors’ conclusion essentially ends up being a recommendation that the whole world should adopt the Jewish dietary laws (though they don’t refer to them as such). As they say,

‘Both iron and calcium are nutritionally essential. Present interactions between calcium and iron must be considered in dietary recommendations, in the composition of single meals, and in the design of daily menus in order to satisfy the requirements for both nutrients in a feasible way…. Attempts should be made to keep the calcium content low in main meals providing iron. This can be done, for example, by reducing the intake of dairy products with these meals and by covering calcium requirements in breakfast meals and in the in-between meals.’

And there you have it, a bona fide medical order from Dr Leif to separate your milk and meat.

But there’s always a flipside : Unfortunately, it turns out that this aspect of kashrut comes with a gender divide; keeping milk and meat separate is good for females’ health but not for males’. The issue was raised in an article about the quality of ultra-Orthodox teenagers’ bones. The teenagers’ risk factors for poor bone quality were pinpointed as being ‘engagement in scholarly rather than physical activity’ (no weightbearing exercise), ‘modest dress and usually inner-city dwelling’ (reduced sunlight exposure, needed for making vitamin D) and, of course, keeping milk meals separate from meat meals (possibly reducing the calcium intake).

The results in this study were pretty shocking. While the girls’ bones were OK, the boys had a mean z score value of -1.71, which is osteopenia (often described as ‘early osteoporosis’, and meaning their bones are already pretty crumbly). That this could be the norm in a population of boys aged 15 to 19 years old from Brooklyn, New York, is really quite frightening – and, even worse, 27% of the boys already had established osteoporosis. These boys should be at their peak bone mass, but instead they already had the skeletons of 80-year-olds.

One possible explanation for the gender difference is that while the girls took a balanced approach to choosing milk versus meat, the boys chose to eat meat almost every meal. This meant they were getting next to no calcium, resulting in absolutely rubbish bone quality.

So the key to getting the balance right? Reviewing the above articles suggests; keep milk and meat separate, but try to alternate the meals. And preferably (but more controversially) don’t wait 6 hours to have your yoghurt.

Some miscellanies (gefilte fish and vodka)

Gefilte fish: Fish is considered a bit of a wonderfood these days, with the news that omega-3 fatty acids increase intelligence. Since gefilte fish is usually a blend of at least 3 kinds of fish, you’d think it should be gefilte the brim with those fatty acids, and thus high up on the list of winners.

But some bad news has been broadcast to the world from JAMA, the Journal of the American Medical Association (how on earth did multiple articles on such an obscure food make it into such a high-profile journal?)

Apparently the bad news is that gefilte fish may contain parasites, putting you at risk of contracting diphyllobothriasis. With a name like that, it’s already scary. The larval parasites (baby form) are tiny, and therefore no amount of chopping or blending is guaranteed to satisfactorily destroy them. The symptoms are abdominal discomfort, vomiting, diarrhoea and weight loss. The parasites – who, by the way, grow up to 10m long – stay in your gut for decades, and can even cause a total blockage of your whole gut. Not even a double-dose of chrain will save you.

A further risk arises when the gefilte fish is home-made. Several cases of botulism have been reported under these circumstances, sometimes with fatal outcomes. It has been observed that the simmering process fails to inactivate the Clostridium botulinum spores (the dangerous bit).

So, it seems that gefilte fish fails. I should probably reveal my bias here. I’m really not a fan of gefilte fish, and therefore glad to find some backing for my prejudice. And as far as I’m concerned, any fatty acid requirements can easily be filled by a liberal intake of smoked salmon bagels.

Vodka : There are obviously plenty of articles on alcohol in general, but unfortunately none that specifically examine kosher wines. Other than kiddush wine, I felt that vodka would surely come second-place as the drink of choice of many Jews.

The verdict seems to be that if used appropriately, vodka has clear benefits. One study, led by a Dr Cohen, discovered that vodka can help to prevent stomach ulcers. Truly. Maybe. One of the problems with taking aspirin is that it can trigger an ulcer in the stomach. So Dr Cohen gave half his patients vodka before their aspirin – and the other (unlucky) half just got an aspirin. The ones who had vodka beforehand got considerably less stomach damage from the aspirin, which I consider to be one of the more exciting medical discoveries made this century. Importantly though, the vodka has to be taken in a small dose; Cohen used 37.5mL, which I suppose is a shot.

But, you could ask, what did I mean by ‘appropriately used’? Well…..there is one case report on a 23-year-old woman who allowed her boyfriend to pour a bottle of vodka (a whole litre?? – it doesn’t say) into her rectum. Not so surprisingly, she developed rectal bleeding and diarrhoea, losing part of the inner lining of her colon. Notwithstanding this tragic tale, it seems that for those who can remember which end the Stolichnaya goes in, vodka can be good for you.

And on that happy note, the meta-analysis of Jewish food is done. Next up, will be religious practices.

Print Friendly


  • Michael says:

    It might be problematic to equate nutrition from meat to iron absorption. There are many sources of iron besides meat and I don’t think anyone living in an industrialised country who eats meat (even with the 59% efficiency when you add calcium) will be deficient in iron.

    It would be interesting to see how consuming milk and meat might affect absorption of other nutrients: for all we know it could hinder some while helping others.

  • frosh says:

    Hi Liz,

    You wrote:

    “Swedish researchers found that calcium blocks the absorption of iron in your gut …I n other words, you only get a little over half the nutritional value from your meat if there’s a slice of cheese lying on top of it.”

    So, I assume this would have ramifications for non-fleish eaters too.

    For example, I am told that for vegetarians, mushrooms are one of the best sources of iron (at least that’s what the mushroom board advertises: ‘It’s meat for vegetarians!’).

    Now it happens that my preferred form of eating mushrooms is finely chopped up and well cooked on a vegetarian pizza. However, based on the findings you report, the cheese on the pizza is robbing me of the iron content. Damn you cheese!

  • ariel says:

    I worked for a time with an Indian fellow who, when I explained to him that Jews don’t mix meat with dairy, was shocked. He explained to me that this was great and that in his religion (Hinduism) they are taught that mixing meat with dairy in the body is very unhealthy and creates physical as well as spiritual toxins.

    Gefilte fish:
    I’m in trouble as it’s my staple every Friday night

    I don’t like vodka at all, but I do love an occassional (read, frequent) scotch.
    However, my Russian Jewish cleaners told me that the best cure for a cold/flu is to fill a glass (yes, 200-250mL!!) with vodka, to add a few good shakes of pepper and to guzzle the whole thing down in as few gulps as possible (ostensibly skulling). Then you lie down in bed and wake up 2 days later feeling like a million dollars!
    I tried this once on a small scale when I had blocked sinuses. A shot of vodka with a bit of pepper cleared me up.

    By the way Liz, you may like to have a look at this document on tefillin and acupunctre as part of your next piece on religious practice: http://www.koshertorah.com/PDF/tefilin.pdf

  • Liz says:

    Michael, I totally agree that mixing meat and milk is unlikely to result in iron deficiency in the average Australian given our abundant supply of iron sources. The authors of the article also agree with you, saying that only groups with increased iron requirements (children, teenagers and women at childbearing age) are likely to be affected in real life by the decreased absorption.

    I find it interesting, however, that the Jewish food laws, evolving at a time when meat was possibly a rarer commodity, work to maximise the iron absorption per kilo of meat eaten. Another article, which I didn’t discuss because it was more discursive than experimental, suggested that historically in different cultures, meat-limiting food laws allowed women greater access to and shares of the meat (ie, they didn’t get it when the men got first dibs and they only got the scraps). So it seems like women are winning on a couple of counts with kashrut.

    Re frosh’s pizza, there are 2 major kinds of iron – haem-iron (mainly the meat kind) and non-haem-iron (basically in vegies, ie the hypothetical mushroom pizza). The literature says both kinds of iron are affected by calcium, so it seems logical the cheese on the mushroom pizza could be having an effect. However, there are also ways to improve iron absorption – for example, having vitamin C at the same time – so maybe a glass of OJ could counteract the effect. Not to completely dictate your diet or anything!

    And finally, thanks for the great reference Ariel, I’ll definitely be incorporating it :)

  • ittay says:

    Hi Liz,
    There seems to be some evidence that the ideal Jewish diet actually involves no meat at all. This is based on the pasuk “See, I give you every seed- bearing plant that is upon
    all the earth, and every tree that has seed-bearing
    fruit; they shall be yours for food” (Genesis 1:29)” It is interesting to note that the pasuk does not read ““See, I give you every four legged creature that is upon all the earth for you to blend into meat pies or sausages”

    Some rabbis talk about the eating of meat only being permitted only as a concession to human weakness, rather than as an ideal. Some rabbis also say that in the time of mashiach, the Jewish diet will again be vegetarian.
    With this in mind, id be interested to hear your thoughts about whether the vegetarian or meat based diet is better for us.

  • ariel says:

    ittay, that’s very interesting.

    In fact there are and have been rabbanim who maintained vegetarian diets ostensibly for the reasons you give.
    Rav Kook for example would only eat a k’zayit (olive size) of meat once a week on Shabbat in order to fulfill the requirements of the day. He recommended a vegetarian diet to his students.

  • The Hasid says:

    Love this!

    Perfectly justifies my proclivity for lipid-rich, Jewish Eastern-European fare :-)

2 Pingbacks »

Leave a comment!

You must be logged in to post a comment.