Eating highly refined carbohydrates after menopause is associated with increased risk for depression in women, according to a new study.

It's part of an increasing body of evidence pointing to a close relationship between diet and mental health.

Refined foods including soda, sweets and white rice ultimately reduce blood sugar levels, which could lead to mood changes and fatigue, say the researchers.

Carbohydrates' effect on blood sugar levels is highly variable, and a measure called glycemic index (GI) is used to distinguish foods from one another on these terms.

The GI measures how much sugar remains in the blood after eating.

It ranges from zero to 100, and the highly refined carbohydrates tend to have a higher GI.

Glycemic load (GL) is a measure used to estimate how much an individual's blood glucose level will spike after eating a particular food.

GL is based on the GI and is determined by multiplying the grams of carbohydrates in the food times the GI.

Working with data from over 70,000 postmenopausal women, the research team from Columbia University Medical Center assessed their diets for GI and GL, taking into account the types of carbohydrates consumed.

Weighing nutrition data against incidence of depression within their participant group, the researchers uncovered an association between a progressively higher GI and increasing odds of depression.

What's more, they found that consuming lactose, fiber, natural fruits and vegetables was strongly associated with a reduced risk of depression.

Researchers note that further investigation is required in the area but the findings could eventually have key implications for emerging evidence suggesting that dietary interventions could help treat and prevent depression.

Last year, a UK team found that eating five servings of fruits and vegetables per day was associated with better mental well-being.

Working with over 14,000 participants the researchers concluded that 33.5 percent of those with high mental well-being reported getting their five-a-day.

The same team found in 2012 that mental well-being peaked at seven portions per day of fruits and vegetables.

The study on refined carbohydrates was published in the American Journal of Clinical Nutrition.