It’s common to think about eating for a healthy heart or gut, but the same food-as-medicine principles also apply to the brain.

That’s especially important to know for women, who make up two-thirds of Alzheimer’s disease cases. What they eat now — in their 20s, 30s and beyond — could help prevent dementia decades later.

Perimenopause — the period when a woman starts to produce less estrogen, usually in her 40s — may be a critical point in whether she’ll go on to develop Alzheimer’s or not.

That’s when it may be helpful for women to get a baseline brain scan, said Lisa Mosconi, a neuroscientist and nutritionist, and author of “The XX Brain: The Groundbreaking Science Empowering Women to Maximize Cognitive Health and Prevent Alzheimer’s Disease.” The title refers to the two X chromosomes that define the biologically female sex.

But it’s diet that can have a real daily impact.

“From a biological perspective, food is not just food. Food is information, food is molecules that will enter your body and end up inside your brain, and they do serve a very specific function in the brain,” Mosconi told TODAY.

“So depending on your food choices, you can eat foods that contain nutrients that are really helpful to the brain.”

For example, neurons in the brain communicate with each other using neurotransmitters like serotonin, which regulates mood and is made from tryptophan, an amino acid that’s not produced by the body — people must get it from food, Mosconi said.

She studies how lifestyle can reduce Alzheimer’s risk — especially for women — as director of the Women’s Brain Initiative and associate director of the Alzheimer’s Prevention Clinic at Weill Cornell Medical College in New York.

Here are Mosconi’s tips for a well-nourished brain:

Studies show these vitamins are specifically important to maintain brain energy levels in women.

“The brain is a very metabolically active organ and it’s very delicate in some ways — it’s very vulnerable to oxidative stress and free radical production,” Mosconi said.

“The best way to protect our brains against aging and free radical production during aging is to import anti-oxidants from our diets.”

They include:

Vitamin A: found in fruits and vegetables that have an orange-red color, including carrots, sweet potatoes and butternut squash.

Vitamin C: good sources include citrus fruits, such as lemons, grapefruits and oranges; berries, including goji berries; and dark leafy greens.

Vitamin E: found in almonds, nuts and seeds, extra virgin olive oil and other vegetable oils.

Choose food rather than vitamin pills since dietary supplements don’t work as well as a well-rounded diet, Mosconi said.

Polyunsaturated fat is one of the “healthy fats” and includes omega-3 fatty acids.

The brain needs DHA, a type of omega-3 fat, for cellular and neuronal health, and since the body doesn’t make essential fatty acids, it must be obtained from the diet, Mosconi noted.

The best sources are cold water fatty fish — think of the acronym SMASH: salmon, mackerel, anchovies, sardines and herring.

Vegetarians or people who don’t like fish can get a different type of omega-3, ALA or alpha-linolenic acid, from plant-based foods including flaxseeds, extra virgin olive oil and almonds.

“What’s important to remember is that the omega-3s contained in plant-based foods need to be converted into DHA in the brain and the conversion is not perfect. Almost up to 70% of this fat is lost in the conversion so you need to eat more to compensate for the loss,” Mosconi said.

Women and men who consume at least 2 grams of omega-3s per day have a 70% lower risk of dementia later in life compared to people whose diets don’t contain enough omega-3s, she noted.

Studies point to eating fish about two or three times a week and regularly eating plenty of plant-based foods that contain polyunsaturated fatty acids.

There’s concern the natural drop in estrogen during menopause means women lose an important layer of protection for their brains.

Many turn to hormone replacement therapy for relief from menopause symptoms, including hot flashes, night sweats and insomnia.

But that option is not for all women and researchers don’t know if taking hormones that way can reduce the risk of Alzheimer’s, Mosconi said.

Another approach is to eat a diet rich in foods that contain phytoestrogens, which is effectively like receiving a mild estrogen replacement therapy without the side effects, she noted.

Soy is one of the biggest phytoestrogen sources, but Mosconi was concerned that it’s often polluted and genetically modified in the U.S. Other options include flaxseeds and flaxseed oil; sesame seed and sesame oil; dried apricots; legumes like chickpeas, lentils and beans; and grains, especially oats and wild rice.

Fruits, including cantaloupes and berries, are other good sources. Dark chocolate also contains some phytoestrogens.

“If you think about the different foods that contain phytoestrogen, those are all really key ingredients of the Mediterranean diet,” Mosconi noted.

“It’s the one diet that’s been consistently shown to reduce the risk of Alzheimer’s and dementia and to specifically benefit women.”