Since I grew up Chinese, I'm familiar with the advice that pairing certain foods together may be poisonous. While some of these allegedly toxic combinations may seem odd or superstitious, it is actually true that chemicals from different foods could interact and create a toxic compound. It is well-known in science that eating ink cap mushroom and drinking alcohol will cause acute poisoning reaction that includes face reddening, palpitation, vomit, tinging of limbs, and even heart attack. Also, high-oxalate foods could cause kidney stone when the oxalic acid reacts with calcium to form a barely-soluble salt that tends to deposit in kidneys. It is generally fine to eat them, but pairing them with milk (which supplies the calcium) will both inhibit calcium absorption and exacerbate kidney stone production. There are reports that tannin binds with proteins and inhibit their absorption. Foods like tea and persimmon are high in tannins, and the Chinese wisdom of avoiding them with protein rich foods like crab meat probably has a scientific explanation.
In the Bible, one instance of forbidden food pairing stands out:
“Do not cook a young goat in its mother’s milk.”––Exodus 23:19, Exodus 34:26, Deuteronomy 14:21.
This has given rise to the strict separation of meat and dairy in Kosher law, requiring two different sets of cooking instruments to prepare meat and dairy foods respectively, even separate meat and dairy microwave ovens for the reheating of the foods. While one can argue that is going above and beyond, there are several levels of generality when interpreting what exactly is forbidden:
- Any young goat and its biological mother's milk (the most specific).
- Goat meat and goat milk.
- Meat and milk of another mammal (e.g. cheeseburger made of beef and cow dairy).
- Meat of one mammal and the milk of another mammal, as long as they are different species (e.g. steak and goat cheese).
- Meet of non-mammal and dairy (e.g. chicken parmesan, fish and cheddar).
- Meat and egg of non-mammal species (e.g. Oyakodon).
(Also, the literal interpretation of the forbidden action is cooking meat and milk together, regardless whether the food is eaten. It's unclear whether eating meat and milk together even though they are cooked separately is also forbidden.)
I was surprised to find that someone in Australia had created a recipe for stewing goat meat in goat milk infused with truffles. Just the goat and goat milk sounds rather unappealing, but they added truffle as the devil's temptation, and tried to legitimize it by giving it an Italian name. However, true Italian Capretto is never stewed in milk.
While one can debate incessantly about how to interpret this verse, and whether the prohibition is due to moral reasons or idolatry, I think there is a health benefit for not eating meat and dairy together, and doing so may be the reason for high cholesterol, which causes clotting of arteries, and ultimately resulting in heart attack. Despite decades of medical research, the way we understand how the cholesterol pathway causes blood clot is only getting more complex and nuanced. A research in 2013 linked red meat to high cholesterol through gut bacteria metabolite, rather than through direct absorption of saturated fat or cholesterol into the bloodstream.
I think that eating meat and dairy together increases blood cholesterol level, while these foods are safe to eat separately, so avoiding that combination would lower the risk of heart attack. It is found that Ashkenazi Jews have a genetic condition that makes them especially susceptible to high cholesterol, so the dietary law might have been given for their benefit.
I'm not aware of any scientific research done for this hypothesis, but I think it will be a worthwhile study. Perhaps such scientific study on the pairing of various meats and daily will inform us which interpretation of the verse is right.