PKU: A Medical Model of Kashrut?

The Jewish soul is sensitive to the harmful spiritual effects of forbidden animals. The sages have written that the dietary laws, which are designated specifically for Jews is likened to a doctor who gives out two different prescriptions for two patients who report the exact same symptoms. The doctor can diagnose what is best for them by examining their makeup, and what is most beneficial for their bodies. To the patients, upon superficial examination, may appear entirely similar, yet the doctor can see a more accurate picture. In this case, the doctor is Hashem who prescribes which diet is tolerable for each soul.1

In Chassidic thought, everything in the spiritual world has a counterpart in the physical. This permits thought for the existence of spiritual molecules based on the knowledge of chemical structures. In other words, the molecules studied in chemistry could be thought of as the reflection of the intangible spiritual molecules the Creator used as a blueprint. Based on this, Dr. Velvl Greene provides an answer to those who reject kashrut because they lack empirical proof.

There is a medical condition called phenolketoneuria or PKU. It is a hereditary metabolic disorder affecting about one out of 15,000 children born in the northern hemisphere and leads to an irreversible and severe retardation.

The newborn child appears healthy and normal. He cannot really be distinguished during a routine physical examination, from his 14,999 unaffected peers. Over the course of several years he develops a characteristic appearance and brain damage.

After a while, physiologists determined that the brain damage was a result of the accumulation in the body of phenylalanine. Normal people have the ability to metabolize phenylalanine and to convert it to other, non-harmful nutrients. But one child in 15,000 lacks the necessary enzyme and the phenylalanine accumulates until it harms the developing brain.

Around 50 years ago, American bacteriologist Robert Guthrie devised a blood test which permits the early diagnosis of PKU, within a few days after birth. This test is now compulsory in most Western countries. Every baby born in a hospital is tested for PKU. If the results suggest that the condition is present, the mother is provided with nutritional advice and counseling. If the diet is modified early enough, if the phenylalanine-containing protein is replaced with a synthetic substitute and fed for the first four or five years, the retardation can usually be avoided. The solution is not simple. It is also inconvenient, unappetizing and expensive. But, it is effective.

Now consider the following scenario: a public health nurse visits a young mother who has just come home from the hospital with her precious newborn baby. The nurse conveys the frightening news that according to the lab tests the baby has PKU. She also provides the mother with a list of prescribed foods and instructions for preparing a suitable preventive diet.

Neither the nurse nor the mother is a chemist. The mother knows nothing about molecules or physiology or metabolism. She knows what she sees — a healthy, normal baby, like any other baby in the world, who enjoys eating and is apparently thriving on the diet being provided. The nurse knows a little more. She has studied a little chemistry and understands the best physiology of metabolism. Or at least, she believes the teachers who taught her. The nurse doesn't really know the basis of the diagnostic tests; nor could she prescribe a diet out of her own experience. All she is doing is her job of transmitting the information she was taught. She believes she is acting in the best interests of the child and the community. But she is mostly acting out of duty and acceptance of higher authorities — such as doctors, chemist and nutritionists — who have studied more and know more and have better sources of knowledge.

The mother refuses to accept the diagnosis or the diet. She does not believe in the mysteries of chemistry or accept the authority of the doctors. Her baby looks normal and happy. Besides, the recommended diet is too expensive and inconvenient and unappetizing. What is all this nonsense about molecules anyway?

What could one tell the mother who demands, “Show me the danger now! Show me the difference between my baby and all the others!” 2


In essence, although the Jewish dietary laws are categorized as a command which transcends logic, the human mind can still get a glimpse of at least some of the benefits and meaning inherent in these laws. Through even brief investigation into the writings of the sages it becomes evident that physical wellbeing is not at all the driving force. Instead, the Jewish dietary laws seek to prevent evil traits from becoming part of the Jew, and as the mystics stress, keeping away from spiritually detrimental energy.

For the one who is new to kosher observance, there is no need to jump into everything at once. Judaism is about progress, not perfection; climbing step by step, on the proverbial ladder of spiritual growth. Every step one does toward enhanced kashrut observance enhances his connection with Jewish tradition and with G‑d.