The chicken pesto pasta on your plate is more than just tasty fuel to keep you going. The dish has carbohydrates, fats and proteins to be sure, but it also contains other nutrients and chemicals that send subtle cues and instructions to your cells. More and more researchers are arguing that to better grasp how diet affects health, experts should consider the signals our food sends.
Cells talk to each other in a complex language of chemical messages. They instruct each other to grow, to move and to respond to threats. Problems in cell communication lead to diseases such as diabetes and cancer. The messages take many forms, including hormones and charged molecules called ions. Cells also listen to signals that come from outside the body.
Recent findings show that molecules found in food can change cell chatter. For example, in 2010 a team of researchers in California and Japan found that omega-3 fatty acids from food bind to a specialized protein studding cell surfaces. That protein, called GPR120, is found in adipose and muscle tissues. When omega-3 fatty acid attaches to the protein, fitting like a key in a lock, GPR120 sets off a chain reaction of cellular events that ultimately protect against weight gain and inflammation.
Understanding the influence of food on cells could offer a better way to design diets, says Randy J. Seeley, the director of the Cincinnati Diabetes Center at the University of Cincinnati. A special diet to tone down inflammation might also combat weight gain or protect against diabetes.
Seeley and his colleague, Karen K. Ryan, argue that food's effects on the body are so complex and specific that a meal is almost like a cocktail of hormones.
Hormones are chemicals pumped out by one tissue or gland that travel through blood or body fluids to reach another part of the body. There, they instruct targeted cells to produce some other chemical or action. While food components aren't produced in the body, they can elicit specific reactions from cells, making them much like hormones. Seeley and Ryan explain the comparison in the February 22 issue of Science.
The metaphor of food as hormones is interesting, says Donald Jump, a professor and biochemist at the School of Biological and Population Health Sciences at Oregon State University. "It's really clear that food is just a pile of biochemicals," he says. "Trying to sort that out is a mess."
Jump explains that researchers have been trying to understand of how food can regulate and influence cells for decades. The public health challenge is translating these specific findings into clear diet recommendations.
Current recommendations do jibe with the newer findings: For example, The American Heart Association advises people to eat fish because omega-3 fatty acids have been linked to heart-healthy measures including reduced risk of abnormal heartbeats and slightly lower blood pressure. Those guidelines, and others, are based on large-scale population studies. Seeley says that in the future, scientists might know which foods promote health by understanding the way the food interacts at the cellular level. Diets could be designed "from the bottom up," he says.
Dietary messages to the public need to be kept simple, Jump says. But they also need to be informed by an understanding of the hormone-like actions of food.
Fatty acids aren't the only hormone-like food elements. Amino acids can also activate a chain reaction of events in cells related to cell growth and insulin. Vitamin D and other vitamins are involved with the body's immune response. More interactions could be discovered: the receptor activated by omega-3 fatty acids is part of a family of proteins call "G-protein coupled receptors" that are involved in cell signals. Scientists know what many members of the family do, but they still don't know what molecules turn them on or off, Seeley says. These locks in search of keys could also play a role in food and cell receptor interactions.
The idea of food acting like a cocktail of hormones "certainly establishes a basis for further research," writes the New York University professor of nutrition and public health Marion Nestle in an email. "In the meantime, for most practical purposes, healthy diets are still composed of plenty of vegetables, relatively unprocessed foods of all types and balanced calories."