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food for thought

If you don’t give much thought to magnesium, you should.

A higher intake of this under-consumed mineral, plentiful in spinach, black beans and nuts, helps guard against hypertension, type 2 diabetes, heart disease and stroke.

Now, new evidence from the Australian National University suggests that significantly upping your daily magnesium intake can lead to less brain shrinkage as you age, which is linked to better cognitive performance and a lower risk of dementia.

What’s more, magnesium’s brain-protective effects may begin as early as your forties.

Here’s what to know about the new study, plus the best foods to boost your magnesium intake.

Aging, brain volume and white matter

As we get older, we lose brain cells (brain atrophy) and the volume of our brain gets smaller too.

Over time, changes in brain structure and loss of brain volume can affect cognitive abilities, including memory and the ability to plan, communicate and regulate movement and emotions.

White matter, made up of nerve fibres deep in the brain, provides connections between different areas of the brain. White matter lesions occur when brain cells are damaged or inflamed. As the brain ages, white matter lesions increase and are associated with a greater risk of cognitive decline.

The study findings

The study, published last month in the European Journal of Nutrition, involved 6,001 cognitively healthy adults in the United Kingdom, ages 40 to 73.

Participants completed an online diet questionnaire five times over a 16-month period. The responses were used to calculate daily magnesium intake from foods.

At the start of the study, participants underwent brain imaging to assess brain volume and white matter lesions.

After accounting for other risk factors (age, sex, body mass index, education level, diabetes, smoking status, physical activity, alcohol intake), a higher dietary magnesium intake was strongly associated with higher brain volumes and lower white matter lesions.

Compared to someone with a normal magnesium intake (350 mg/day), the researchers estimated that someone who consumed more (at least 550 mg/day) would have a brain age one year younger by the time they reached age 55.

Because the findings were observed in middle-aged participants, they suggest that a higher dietary magnesium intake may begin to slow brain aging in the forties and possibly earlier.

The results also showed that a higher magnesium intake was more beneficial for women compared to men, especially postmenopausal women, possibly related to changes in estrogen.

This isn’t the first study to associate dietary magnesium with better cognitive health.

Research conducted in middle-aged and older adults has tied higher magnesium intakes to a lower risk of dementia. Higher dietary magnesium has also been linked to a lower risk of progressing from normal aging to mild cognitive impairment.

How magnesium may protect brain health

Higher magnesium intakes have been shown to decrease elevated blood pressure, an established risk factor for dementia.

The current study, however, didn’t find any connection between magnesium intake and blood pressure, suggesting that magnesium works in other ways to protect the brain.

It’s known that magnesium reduces oxidative stress and inflammation in the brain, harmful processes thought to be major contributors to loss of brain cell structure and function and Alzheimer’s dementia.

A higher magnesium level in the brain has also been found to enhance how brain cells communicate with each other.

How much magnesium? Which foods?

Adults require 310 to 320 mg (females) and 400 to 420 mg (males) of magnesium a day.

According to the 2015 Canadian Community Health Survey, more than half of adult males and females do not meet these daily recommended intakes.

Cooked spinach and Swiss chard are excellent sources of magnesium, each providing 160 mg per one cup. Acorn and butternut squash contain 88 and 60 mg of magnesium per cup, respectively.

Pulses are also outstanding magnesium sources. Per one cup: black beans (120 mg), navy beans (96 mg), pinto beans (86 mg), chickpeas (80 mg) and lentils (70 mg). Soybeans, edamame and soy milk are good sources too.

Seeds and nuts are also high in magnesium. One-quarter cup of pumpkin seeds and sunflower seeds each contain 162 and 114 mg, respectively. Hemp seeds have 116 mg per two tablespoons. Chia seeds, almonds, cashews and peanuts are other good sources.

Whole grains such as teff, quinoa, spelt berries, bulgur, whole wheat pasta, brown rice, oats, oat bran and bran cereals are also decent sources of the mineral. So are chinook salmon, Atlantic mackerel and halibut.

Unlike magnesium supplements, magnesium-rich whole foods also contain vitamins, other minerals, fibre, healthy fats and phytochemicals, food components thought to work together to provide health benefits.

Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD

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