Common causes of depression

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Headspace can be a vexed place. One week you're so high on life you want to write a bestseller and blitz that 14-K run. The next, you can barely muster a grimace.

The number of Aussie women experiencing low moods is higher than ever - one in five aged 28 to 33 has been diagnosed with depression.

In a survey of 5329 Women's Health readers, more than 24 per cent of you say you're hounded by the black dog, and a study funded by the Department of Health and Ageing found this age group buys more antidepressants than any other medication.

If job stress, money, health or relationship problems aren't beleaguering you, and you've ruled out a genetic cause, see whether any of the following strike a chord with you.

YOU FEEL bloated, gassy and crampy

The suspect Fructose malabsorption (FM) or undiagnosed digestive problems. (This can also be diagnosed as irritable bowel syndrome. FM is an inability to fully digest fructose, a naturally occurring sugar found in loads of fruits, some vegies and honey.)

The evidence What do digestive problems have to do with mood? (Apart from the distressing feeling that you need to give birth to a gas baby.) The fructose-intolerant may have a reduced capacity to produce serotonin, the mood-controlling chemical, according to a study of subjects with gastro problems by the University of Innsbruck in Austria.

When the gut lining is inflamed (which can happen with digestive conditions), you're less able to absorb nutrients necessary for energy production, says Judy Davie, food and nutrition writer and co-author of Star Foods.

"Unrecognised malabsorption through coeliac disease can also cause low energy and trigger depression," adds beyondblue clinical adviser and psychiatrist, Associate Professor Michael Baigent.

The rehab Take a simple hydrogen breath test when you next visit a doctor. If diagnosed, you'll need to get fresh with a low-fructose diet and keep an eagle eye on food labels, since many products contain fructose as a sweetener. "Try to eat fruit on its own rather than mixing it with grains or nuts - that way it's easier to absorb," says Davie. "Also, chew fruit slowly, and avoid fruit at night time."

YOU FEEL downright miserable

The suspect Hormones in your birth-control pill

The evidence A study conducted at Monash University in Victoria examined 62 women over age 18 and found those taking a contraceptive pill containing both oestrogen and progesterone were almost twice as likely to be depressed as the non-pill poppers. The women in the study had no clinical history of depression.

The rehab "If you do suspect that the pill is causing your depression, the only way to know for sure is to come off it and see what happens," says Women's Health health expert Dr Ginni Mansberg.Talk to your GP if you suspect this could be a problem for you.

"And in the meantime, use other forms of contraception and give your mental health a boost by exercising, cutting back on alcohol and seeking counselling if you need it," says Dr Mansberg.

YOU FEEL just "blah"

The suspect Not eating enough fish

The evidence A high intake of omega-3s can reduce the frequency of depressive symptoms in women by up to 30 per cent, according to a US study published in the journal Nutrition. Interestingly, the researchers found that mens' moods didn't respond as positively when plied with fish meals.

The rehab "The brain is comprised of DHA (an acid that helps make up omega-3 long-chain fatty acids), so when you're eating fish, you're directly feeding the brain," says Davie. Naturopath Siobhan Jordan recommends eating around three serves of fish a week.

If you find seafood too fussy to cook, keep in mind that it can be as easy as wrapping a swimmer in foil with cracked pepper, salt and lemon juice and baking in an 180ºC oven for less than 10 minutes. (That's the kind of fast food we love.)

But if you're not into the taste, consider an omega-3 supplement - 1000g a day is decent, although some health professionals recommend doubling, tripling or even quadrupling this dosage.

YOU FEEL tired, lethargic, cold, constipated, forgetful and have an irregular menstrual cycle

The suspect Low thyroid function

The evidence One in seven Australians will be diagnosed with a thyroid condition, and women are five times more likely to suffer from this type of illness than men. Hypothyroidism (an underactive thyroid) has been linked to depression for eons - well, since the 80s at least. A 1981 study published in the Journal of the American Medical Association examined 250 hospital patients admitted for depression and found about eight per cent had hypothyroidism.

More recent research, published in the The International Journal of Neuropsychopharmacology (try saying that three times, fast), found thyroid hormones enhance women's response to antidepressants (provided, of course, they have hypothyroidism in the first place).

The rehab "If you have hypothyroid symptoms and are also feeling down, ask your doctor for a thyroid test," says Beverley Garside, President of the Australian Thyroid Foundation. "Doctors can often overlook thyroid and prescribe an antidepressant which, in some cases, makes things worse."

Iodine deficiency is a major player in thyroid disorders (iodine helps you produce thyroid hormones), and various studies, including one by NSW's Institute of Pathology and Medical Research, have shown this deficiency is widespread in Australia.

Start getting your fill by throwing that fancy sea salt over your shoulder and replacing it with the iodised variety, suggests Garside. You can also get iodine from seafood, so fish does double duty in preventing low mood.

Go to beyondblue, the website of Australia's national depression initiative, for more comprehensive information about low moods and depression.