Originally published in 2010

Call it “the blues,””a funk,” or waking up on the wrong side of the bed,” we’ve all felt it at one time or another: Fro no particular reason, you feel sad or anxious for a day, a week, and maybe even several weeks. Muddled thoughts and low energy slow your productivity and wreak havoc on your days. You scour your brain to try to pinpoint what’s bothering you, but come up empty.

For decades scientists have believed that depression arises from deficiencies (some of them genetic) in brain chemicals like serotonin. But researchers now realize that blue moods can also be a product on an unhealthy brain structure made up of withering brain cells that, consequently, have trouble communicating. One primary factor that contributes to cell atrophy? A poor diet, says Alan C. Logan, ND, author of The Brain Diet. Here are five dietary factors and other lifestyle habits that can mess with your mood.

1. Skipping breakfast

Do you start your day by munching down a doughnut in the car, or with no breakfast at all? Not fueling your body in the morning will only backfire, Logan says. Blood sugar dips, sending your body into fight-or-flight- mode. This drenches your system in stress hormones – such as cortisol and adrenaline – that interfere with mood and thinking. If you have simple carbs, like a doughnut, you get a fleeting lift but then crash even harder than if you’d eaten nothing.

What you can do

Always eat an ample breakfast of complex carbohydrates and protein, such as whole-grain toast with poached eggs or low-fat yoghurt and granola. Wholesome carbs provide fuel for the brain and have a mood-stabilizing effect. Protein provides the building blocks (amino acids) for feel-good chemical messengers, such as serotonin.

2. Eating the wrong fats

When it comes to promoting a healthy mood, getting the right ratio of omegas is critical. Omega-3 is essential fatty acids, found in cold-water fish, walnuts, flaxseed oil, olive oil, and green leafy veggies, make up the scaffolding of the brain. If you get plenty of omega-3, you end up with a well-oiled machine, but most of us get too many omega-6 fatty acids (found in corn, sunflower, safflower, and peanut oils) instead. The result: rigid brain-cell membranes and poor cell communication. One recent study found 1,000 mg of EPA taken daily for eight weeks was effective in treating depression as Prozac.

What you can do

Read ingredient labels to avoid overconsuming omega-6 oils. Eat at least two helpings of oily fish per week, and for backup take a fish-oil supplement (up to 1,000 mg per day of EPA-DHA combination). Vegetarians and vegans take note: Fish oil is the best source of omega-3 says Logan, because it contains DHA, which influences the shape and structure of brain cell membrane and EPA, which expedites communication between cells.

3. Low folate and B12 intake

These key B vitamins play a multifaceted role in regulating mood. They serve as building blocks for pleasure-promoting neurotransmitters, such as dopamine; foster nerve health; and flush the body of the mood-compromising amino acid homocysteine. An affinity for refined grains (such as white flour, in which the folate has been stripped out during processing) and a distaste for fresh vegetables (high in folate) has left as many people low in this nutrient. Adults lacking enough B12 – found in lean red meat, eggs, and milk – are 70 percent more likely to suffer depression.

 What you can do

Eat whole grains and green leafy vegetables, and take 800 mcg of folic acid and 1 mg of B12 daily.

4. An erratic exercise routine

According to a new study in the Journal of the American Medical Association, regular aerobic exercise-such as running, cycling, or brisk walking – boosts mood. “People who exercise on a regular basis tend to report less depression and anxiety,” says Benson Hoffman, PhD. Some animal studies have shown that exercise enhances neuropeptide Y, a brain chemical associated with stress resilience, and dampens the influence of another brain chemical called CCK-4, which is responsible for inciting feelings of panic.

What you can do

After a 10-minute warm-up, get your heart rate up to between 70 percent and 85 percent of your recommended minutes, three to four times per week. (For instance, the maximum heart rate for a 40-year old woman in relatively good health is 180, making her target heart rate between 126 and 153). Hoffman’s research found that a similar 16-week program proved just as effective as a daily dose of the antidepressant sertraline (Zoloft) but he stresses that you have to exercise often to see a difference. “When you get down to two days a week, you may not see a difference at all.”

5. Succumbing to negativity

Ed Diener, PhD, a psychology professor at the University of Illinois, says the way you view your world can have a direct impact on mod. You might hold grudges, see the glass as half empty, and remember the bad times rather than the good, and forget to pencil in time to do what you love. Seeing happiness an as endpoint – a place you reach when you have the right spouse, right car, right job – can leave you feeling stuck when you get all that, or don’t.

What you can do

Forgive an adversary. Look back on good memories. Pencil something joyful – whether having a bubbly bath or dining with a friend – into each day. And keep looking forward: “Happiness has to evolve with new goals, fresh projects, and interesting activities,” says Diener. “It’s a process not a destination.”