Women should ensure they are getting enough omega fatty acids in their diets according to researchers, who found unusually low levels of the compounds in female patients with Alzheimer’s disease.
The advice follows an analysis of blood samples from Alzheimer’s patients and healthy individuals, which revealed levels of unsaturated fats, such as those containing omega fatty acids, were up to 20% lower in women with the disease.
The low levels were not seen in men with Alzheimer’s, suggesting there may be sex differences in how the disease takes hold and affects a person’s physiology.
“The difference between the sexes was the most shocking and unexpected finding,” said Dr Cristina Legido-Quigley, a senior author on the study at King’s College London published in the Alzheimer’s & Dementia journal. “There’s an indication that having less of these compounds could be causal in Alzheimer’s, but we need a clinical trial to confirm that.”
Alzheimer’s disease is twice as common in women as in men. Factors including women’s longer average lifespan, differences in hormones, immune responses and educational opportunities can all play a role in the development of the disease.
In the latest study, researchers analysed the levels of lipids, which are fatty compounds, in the blood of 306 people with Alzheimer’s, 165 people with mild cognitive impairment and 370 people who were cognitively healthy controls. Lipids can be saturated or unsaturated, with the former considered unhealthy and the latter broadly healthy.
Women with Alzheimer’s disease had higher levels of saturated lipids and lower levels of unsaturated lipids than cognitively healthy women, a pattern not seen in men. Legido-Quigley said that if changes in the liver or metabolism were responsible, less omega fatty acids would probably be reaching women’s brains. “And these lipids feed the brain,” she added.
Diets rich in omega-3 fatty acids, such as the Mediterranean diet, have long been linked to health benefits for the heart, brain and other organs. One study from 2022 found that middle-aged people with higher blood levels of omega-3 fatty acids had better cognitive function than others.
Several trials have found that giving older people omega-3 supplements did not improve their cognitive function or boost mental capacity in those already diagnosed with dementia.
Legido-Quigley wants to see a clinical trial established to test whether supplements can delay Alzheimer’s disease specifically in women with low levels of unsaturated fatty acids, adding that the drop may start to appear when women are in their 50s. In the meantime, she said women should ensure they are getting omega fatty acids in their diets.
There are three essential omega-3 fatty acids, known as ALA, DHA and EPA. ALA is found in plant-based foods such as chia seeds, flaxseed and walnuts. DHA and EPA primarily come from fish. The NHS recommends eating two 140g servings of fish a week, with one being an oily fish, to get enough DHA and EPA.
Dr Julia Dudley at Alzheimer’s Research UK, which co-funded the study, said more work was needed to unpick the mechanisms behind the sex difference and discover whether lifestyle changes, including diet, could have a role in preventing the disease. “Understanding how the disease works differently in women could help doctors tailor future treatments and health advice,” she added.