NEW YORK (CBSNewYork) — When it comes to finding a perfect meal plan or diet, the answer could be as simple as checking your DNA.

As CBS2’s Dr. Max Gomez reported, several companies are jumping on the nutrigenomics bandwagon – the emerging science of how nutrition interacts with your individual DNA.

Every time Rebecca Castle sat down to eat her favorite food, she says she suffered excruciating abdominal pain.

“Yeah — it’s terrible, terrible, like, sharp shooting pain, bloating, distention,” she said.

That pain went on for more than two years. Castle saw multiple doctors and then took a saliva DNA metabolic test.

“I was allergic to starch,” she said. “That’s mostly root vegetables, corn, peas, sweet potatoes.”

Ahmed El-Sohemy is the chief scientific officer at Nutrigenomix.

“Individual genetic differences can help us understand why some people respond differently from others,” El-Sohemy said.

Nutrigenomix says their DNA test looks at a person’s 45 genetic markers. The company makes recommendations based on the patient’s genetic profile, pointing out attributes like “an elevated risk for low iron.”

“We’re talking about metabolic tests,” El-Sohemy said. “They’re genetic tests, but they affect the way that you metabolize various substances that you consume.”

Dr. David Agus is a CBS News contributor.

“DNA tests for diet and exercise just are not validated,” Agus said. “There are very few of them that actually have data behind them.”

The Nutrigenomix website cites a number of stories in the lay press, but CBS2 could not find any scientific stories that supported the company’s claims.

A recent journal article said that a definite association between the genes usually examined in nutrigenomics testing and several diet-related diseases is lacking.

The company website has a disclaimer in very small print: “Nutrigenomix® reports are for information purposes only and are not intended to be used as medical advice.”

Still, Castle said the test worked for her,

“I think it’s worth it,” she said. “You don’t need your blood taken. You’re literally just spitting into a test tube.”

There is a kernel of science behind the interaction of nutrition and genetics. Bu the ability to use your own genome to predict how you will respond to specific nutrients – that science is not there yet.

The tests run about $300 to $500 and are not covered by insurance.