Women, who include foods rich in fatty acids in their diet, can look forward to a nimble mind even in old age, according to a new study.

Researchers looked into the levels of omega-3 fatty acids in blood of older women and found that people with higher levels of the omega-3 fatty acids may have larger brain volumes in old age equivalent to preserving one to two years of brain health.

Shrinking brain volume is a sign of Alzheimer's disease as well as normal ageing.

James Pottala, an assistant professor at the University of South Dakota Sanford School of Medicine in Sioux Falls and chief statistician for the Health Diagnostic Laboratory in Richmond, Virginia, and his colleagues analyzed data from the Women's Health Initiative Memory Study to see whether omega-3s were associated with brain shrinkage in general, and in specific brain regions involved in memory and other cognitive processes.

The data covered 1,111 women who were, on an average, 70 years old and had no signs of dementia at the beginning of the study. At that time, the amount of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in their red blood cells was measured.

DHA accounts for 30 percent to 40 percent of the fatty acids found in brain cell membranes, and it's especially concentrated near the synapses where the cells communicate with one another, according to the study published in the journal Neurology.

The level of Red blood cells of the omega-3s is good indicators of how much a person has consumed, the researchers add.

The researchers used an omega-3 index to describe the fatty acid levels seen among women in the study and to divide them into four groups: women with the highest levels had an average index reading of around 7.5 percent, while women with the lowest levels had an average of 3.4 percent.

Eight years after the women's blood was tested, they underwent MRIs to measure the volume of gray matter and white matter in their brains.

The researchers found that women with the highest EPA and DHA blood levels at the study's outset had brains that were about two cubic centimeters larger overall than women with the lowest levels.

In addition, the hippocampus, a brain region critical to forming and storing memories, was 2.7 percent larger in women who had fatty acid levels twice as high as the average.

Of 13 specific brain regions the researchers looked at, the hippocampus was the only one where they saw a significant difference.

The analysis adjusted for other factors that could influence the women's brain size, including education, age, other health conditions, smoking and exercise.

"These higher levels of fatty acids can be achieved through diet and the use of supplements, and the results suggest that the effect on brain volume is the equivalent of delaying the normal loss of brain cells that comes with ageing by one to two years," said Pottala.