The gene and the plate

The human genome was read out in full in 2003, and almost at once people asked the obvious question: if my genes differ from yours, shouldn't my dinner? In 2004 Jim Kaput and Raymond Rodriguez gave the new field its charter in a paper on nutritional genomics, and José Ordovás, a Spaniard who directs the nutrition and genomics laboratory at Tufts in Boston, has spent the years since finding the places where the answer is yes. His best-known one came in 2009: a common variant in a gene called APOA2 raised the odds of obesity, but only in people who also ate a lot of saturated fat. Same food, different body, different result.

Two genes come up more than any others. APOE has three forms, and about one person in four carries the fourth kind, e4. It raises the risk of Alzheimer's disease later in life and, less famously, tends to send cholesterol higher on a diet heavy in saturated fat, one of the few places a letter in your genome changes what belongs on your plate. MTHFR is the other. A common variant slows an enzyme that handles folate, and the fix the body wants is ordinary: folate from leafy greens, beans and lentils, with folic acid where the diet falls short. The internet has made MTHFR a diagnosis and a supplement aisle; the medical genetics societies have said plainly that for most people the test adds nothing to care.

Here is the plain thing. The dream of a diet read off your genome has mostly not come true yet. In Stanford's DIETFITS trial, published in 2018, 609 adults ate low-fat or low-carbohydrate for a year, and the gene patterns meant to predict who would thrive on which predicted nothing. Europe's Food4Me study found that personal advice beat generic advice, and that adding a person's genes to it added nothing more. The science is real and young. Most of the consumer reports sold in its name are ahead of it.

It's a Healing key because this month is for the hidden number, and your genes are the most hidden of all. The honest use of them is small and specific, and worth knowing. If you've had a genetic test, or are weighing one, the door is a genetic counselor to read it with you, and your physician before you change a supplement; Vault Human coaches and doesn't treat.