Never skip breakfast. Never leave the house without a care package of healthy snacks.

Eat a good mix of carbohydrates and protein with each meal.

Such suggestions sound like good tips for slimming down – but are they also an action plan for fending off depression, stress, anxiety and mood swings?

Absolutely, say some dietitians and researchers.

“The link between food and mood is becoming much more known in a lot of ways,” says Lynn Smith, a Boulder, Colo., dietitian who helps patients use dietary changes to wean themselves off anti-depressants or avoid going on them.

The body of clinical research on the relationship between what we eat and how we feel has grown substantially in the past decade but is still fairly small. Nutritionists caution that not all mental illness can be tackled with changes in diet.

But as prescriptions for anti-depressants and anti-anxiety medications skyrocket, an array of books, lectures and clinics around the country are beginning to emphasize the notion that the food we eat can have a profound effect on our emotional state.

“I don’t think it is being given anywhere near enough attention,” says Elizabeth Somer, a Seattle dietitian and author of “Food and Mood Cookbook.” (2004; Henry Holt) “Many doctors don’t even ask pregnant women what they are eating, much less people who come in with depression.”

Somer and Smith say there are two main factors in diet-related mood problems.

First, people are not eating enough of the right building blocks for neurotransmitters, the chemical messengers that help nerve cells communicate. Second, they are eating too many refined sugars, which cause blood sugar to spike fast and high, then plunge below a healthy level.

At least five critical neurotransmitters are directly related to the foods we eat, writes Somer.

For instance, low levels of serotonin, a neurotransmitter built from the amino acids found in vitamins B6, B12, folic acid and other nutrients, may result in insomnia, depression, increased sensitivity to pain and aggressive behavior.

Low levels of dopamine and norepinephrine – built up with the help of magnesium, B12 and folic acid – leave people feeling irritable and moody. Fatty acids Omega 3 (fish oil) and Omega 6 (certain vegetable oils) also have been shown in some clinical studies to be associated with mood stabilization.

Then there is the sugar roller-coaster.

“If we just got people off the massive quantities of sugar that we do, we would take care of a lot of the depression in this country,” says Smith.

We tend to reach for sugar because it quickly spikes levels of feel-good serotonin, dietitians say. But it also spikes blood sugar levels dramatically within 10 or 15 minutes. When the body tries to stabilize itself, it overcompensates, dragging the level exceedingly low within 25 to 40 minutes. Low blood sugar is associated with depression, fatigue and anxiety.