People with clinical depression are about four times more likely to have a heart attack than other individuals.
People with heart disease are more likely to be depressed. About one in 20 people experience clinical depression in a given year, but the number is one in three among heart attack survivors.
Dozens of medical studies involving tens of thousands of people showcase that strange link between heart attacks and clinical depression.
The old explanation is being challenged by a surprising new idea.
Simply put, it's that bad fat is sad fat. The wrong kind of fat in the diet is bad for both the heart and the brain, and may lead to both heart attacks and clinical depression.
The old explanation was that depression and anxiety have physical effects on the body. They boost levels of stress hormones in ways that can increase blood pressure, raise cholesterol levels, and make blood more apt to clot and plug blood vessels. Depressed people also may be more likely to smoke, be obese, and get little exercise.
The new explanation is that a deficiency of so-called omega-3 fatty acids in the diet may be the missing link between depression and heart disease.
Omega-3 fats are called “fish oils” because the richest sources are oily fish like tuna, salmon, herring, mackerel, sardines, and anchovy. Olive oil, walnuts, and some other foods are other good sources.
Dietary supplements containing omega-3 also are available in the vitamin-mineral sections in stores.
People have been eating less and less omega-3 fat over the last century, due to reliance on processed foods. Packaged foods need a long shelf life, and that means use of soy, corn, cottonseed, and other oils rich in omega-6 fatty acids.
A century ago, people ate a balance of omega-3 and omega-6. Now the typical person eats a dozen times more omega-6 than omega-3. Soybean oil alone accounts for much of the increase. Its consumption has increased almost a thousand-fold in the last 100 years.
How could the kind of fat in the diet affect the brain?
Most people don't want fat on their body, but it's essential in the brain. The brain itself is about 60 per cent fat. Brain cells engage in a constant biochemical chatter, including whispers that determine mood. Those signals get inside brain cells by passing through an exterior coating that is almost entirely fat. A deficiency of omega-3 fats could interfere with the signaling.
There's real-world evidence from research on clinical depression. In some studies, symptoms improve dramatically in people who start eating more omega-3 fats.
How could omega-3 affect the heart?
Studies show that they have beneficial effects on the heart's rhythm, for instance, decreasing the risk of dangerous erratic heart beats that can result in sudden death.
Government recommendations suggest two meals of fish each week. Those meals, or popping omega-3 supplements, may be a good investment in a healthy heart and brain.