My ABCs for brain and eye health

Three simple—and delicious—ways to keep your vision AND your mind sharp, no matter what your age

Natural substances don’t just have one, single mechanism of action. Rather, they have many different active constituents that act in synergy to help them survive and thrive.

That’s why, unlike drugs—which use artificial compounds concocted in a pharmaceutical lab, and are designed to treat a single disease or symptom—foods and nutrients help keep you healthy from head to toe.

So it’s no surprise that there’s new research showing how a variety of nutrients and foods can support both healthy brain function and eyesight.

In fact, these studies suggest that the same nutrients that reach the brain also reach the eye. This makes sense, considering these organs are derived from the same kind of embryological tissue during fetal development.

Consequently, science is now showing that when we talk about preserving good cognitive function in the brain, the findings are typically relevant to preserving good eyesight, too.

And there are a variety of foods and nutrients that have been demonstrated to support both brain and eye health. I call them my ABCs for brain and eye health because they’re that fundamental to healthy function—especially as we age. (Not to be confused, of course, with my ABCs of joint health, that I’ve shared with you many times before.)

So, without further ado, let’s take a look at some simple—and delicious—ways to keep your vision and your mind sharp, no matter what your age…

A is for avocados

Avocados contain monounsaturated fat, which supports heart health. Plus, they’re packed with fiber, which feeds the probiotics in the gastrointestinal (GI) tract and promotes a healthy GI microbiome.

Avocados are also good sources of vitamins B, C, E, and K. They even have more potassium than bananas!

All of this makes avocados one of the original “health foods.” (Remember those Angie Dickinson commercials in the 1970s?) And now, new research shows that these creamy fruits are particularly good for your brain and eyes.

That’s because avocados are loaded with lutein—one of my favorite carotenoids. (Learn more about the health benefits of carotenoids on page 3.)

In fact, one new study showed that the lutein in avocados can improve brain function, and specifically, attention span.1 (That should be good news for all of those avocado toast fans—before they shift their attention on the next trendy food!)

The study looked at adults who were overweight or obese, which is estimated to affect 70 percent of the U.S. population. For 12 weeks, researchers prepared daily meals for the 84 study participants. Diets were identical in nutrients and calories, but half of the participants consumed an avocado each day, and half did not.

The researchers measured lutein levels in all participants’ blood and eye fluids. (It’s rare to measure nutrients within the eye itself, as often done in forensic sciences, but those levels are most relevant to determining eye function.) Participants also completed three tests to evaluate attention span and other cognitive functions.

Ultimately, the researchers found that the avocado group had better performance on their cognitive assessments. They also had markedly higher levels of lutein in their blood and eyes.

Other studies have found similar results. One 2017 study of nearly 50 men and women with an average age of 63 found that eating one avocado a day for six months increased lutein levels in the eye by 25 percent.2 And that also translated into improvements in memory and attention span.

Recommended amount: Two to three avocados per week. And there are much healthier ways to eat them than as a spread on toast. Try an avocado chopped up in a salad, diced into an omelet, or as a tasty topping for grilled chicken.

B is for blueberries

A growing amount of research shows you really can “get your thrill on blueberry hill” (as originally sung by Fats Domino)—at least when it comes to brain and eye health.

As you know, blueberries have become the focus of a number of health investigations in recent years. Studies using both the fruit and blueberry dietary supplements have shown benefits for cancer, cardiovascular disease, cognitive function, and metabolic syndrome.

Initially, it was theorized that the antioxidant properties of blueberry flavonoids were primarily responsible for these benefits. Blueberries are particularly high in anthocyanins—a flavonoid that gives them their deep blue color. (Interestingly, research shows that wild blueberries have three times more flavonoids than their cultivated cousins.)

But recent studies suggest other ways blueberries work to support brain and eye health. For instance, some lab studies show that blueberries reduce chronic inflammation in brain neural tissues. And chronic inflammation has been linked with cognitive decline and dementia, along with other chronic diseases.

Plus, one study on mice found that blueberry, strawberry, and spinach consumption for just eight weeks led to an actual reversal of aging changes in brain cells.3

In addition, studies consistently show that dietary intake of blueberries is associated with better cognitive function and memory.

One of the most compelling was the huge Nurse’s Health Study, which analyzed the diets of just over 16,000 women, ages 70 and older, during a 20-year period. Researchers found that increased consumption of blueberries was related to a 2.5-year delay in cognitive decline.4

Another recent analysis reviewed 11 different studies on blueberries and cognition.5 Four studies looked at adults ages 60 and older. Four studies were on children ages 7 to 10. And three studies looked at adults with mild cognitive impairment (MCI), specifically.

In children, blueberry consumption was associated with increased memory and executive function, like decision-making. In older adults, both with and without MCI, there were improvements in executive function and memory, as well as psychomotor function—which is strongly associated with increased lifespan and longevity.

These results are also particularly important for people without MCI. That’s because most botanical supplements are used to help memory in older adults who already suffer from memory problems—but they don’t boost cognitive function in people without memory problems.

Meanwhile, blueberries are beneficial to eye health, too. One new research review noted that our retinas have the highest cellular respiratory rate of any of our tissues, making our eyes particularly prone to damage from oxidative stress.

And guess what? Blueberries’ anthocyanins may relieve that oxidative stress!

The review cited one study of more than 35,000 women, ages 45 and older, which found a significant association between blueberry intake and lower risk of age-related macular degeneration.6

Sadly, there currently aren’t many other human studies on blueberries and vision—although animal and lab studies do look promising. (As always, I’ll be sure to report on all of the latest research here in my newsletter, as well as in my Daily Dispatch.)

Recommended amount: Half a cup of fresh blueberries per day, or 400 mg of blueberry powder per day (which can be added to water, tea, or smoothies).

C is for carotenoids

Earlier, I discussed the carotenoid lutein, which is found in avocados and other foods. Carotenoids are the pigments that make certain fruits and vegetables red, orange, or yellow. (Indeed, the word actually comes from carrots, which are bright orange.)

But carotenoids do more than just make fruits and vegetables colorful. They also help plants absorb light to use in photosynthesis. And they act as powerful antioxidants in the human body.

There are even a variety of studies linking carotenoids to cancer prevention. And they also have strong anti-inflammatory properties, which helps protect against a whole host of chronic diseases.

In fact, there are more than 600 types of carotenoids. The single most well-known is beta-carotene—even though my research years ago, with scientists at the Human Nutrition Research Lab at the USDA Agricultural Research Center, revealed that healthy foods had far more abundant sources of other carotenoids, besides just beta-carotene.

(But that doesn’t mean you should overlook the health benefits of beta-carotene—or alpha-carotene—in the proper dosages and natural forms, or preferably from foods. Both are tried-and-true carotenoids for supporting healthy eyesight.)

Still, in recent years, there has been more research into some “new” carotenoids—like the lutein and avocado studies I mentioned earlier.

And along with lutein, astaxanthin and zeaxanthin also show intriguing evidence for brain and eye health. Thus far, most of the research focuses on combinations of these carotenoids rather than the individual compounds themselves. Let’s take a look…

Astaxanthin. This potent carotenoid is found in sea plants, and is what gives crab, lobster, shrimp, and salmon (which eat these plants) their pinkish colors.

One new analysis of seven studies showed the benefits of both astaxanthin and lutein for cognitive function in healthy adults without memory impairment (like the blueberry study I mentioned earlier).

Five of the studies focused on lutein supplementation, and two analyzed astaxanthin supplementation. Middle-aged and young adults who took  10 mg of lutein a day for 12 months had consistently improved memory, attention span, and focus. Astaxanthin also showed similar benefits in one of the studies.

And there’s even more evidence on astaxanthin’s effects on eye health. In fact, one new research review found that the carotenoid is effective for treating retinal diseases, cataracts, ocular surface disorders like dry eye syndrome, eye strain, and eye inflammation.7

Zeaxanthin. This carotenoid gives corn, saffron, and other botanicals their distinctive yellow colors.

Several studies link zeaxanthin to lower risk of macular degeneration. And now, researchers are focusing on the link between zeaxanthin, lutein, and brain health.

One recent study involving 62 adults, with a median age of 74, found that taking 10 mg of lutein plus 2 mg of zeaxanthin for one year significantly increased the levels of both carotenoids in the study participants’ eye fluid.

Those who took the carotenoid combination also had significant improvements in attention span, executive function, and memory.8

Recommended amount: See the sidebar on page 3 for wholesome foods that are rich in carotenoids.

If you take supplements, I suggest 10 mg a day of lutein, 2 mg daily of zeaxanthin, and 4-6 grams a day of astaxanthin. (Or you can look for liquid formulas that combine astaxanthin with vitamin D for a one-two health punch.)

SIDEBAR: Brain (and eye) food

The following foods are rich in the nutrients shown in studies to boost both brain and eye health. So, I recommend adding them to your healthy, balanced, Mediterranean-type diet, which is already full of fresh, whole foods. And always try to opt for organic produce whenever possible—which, by law, is free of pesticides, other artificial chemicals, and genetically modified organisms (GMOs), as I discussed in last month’s issue of Insiders’ Cures

  • Apricots
  • Asparagus
  • Avocados
  • Beets
  • Bell peppers
  • Blueberries
  • Broccoli
  • Cantaloupe
  • Carrots
  • Corn
  • Crab
  • Eggs
  • Grapefruit
  • Guava
  • Leafy green vegetables
  • Lobster
  • Mangoes
  • Nectarines
  • Oranges
  • Peaches
  • Pumpkin
  • Salmon
  • Shrimp
  • Squash (yellow and winter)
  • Strawberries
  • Spinach
  • Sweet potatoes
  • Tangerines
  • Tomatoes
  • Watermelon

Sources:

1“Effects of a 12-week Avocado Randomized-controlled Trial on Cognitive Function and Lutein Status Among Adults with Overweight and Obesity (OR05-01-19),” Current Developments in Nutrition, Volume 3, Issue Supplement_1, June 2019, nzz029.OR05–01–19,

2“Avocado Consumption Increases Macular Pigment Density in Older Adults: A Randomized, Controlled Trial.” Nutrients, 2017 Sep; 9(9): 919.

3“Reversals of Age-Related Declines in Neuronal Signal Transduction, Cognitive, and Motor Behavioral Deficits with Blueberry, Spinach, or Strawberry Dietary Supplementation.” Journal of Neuroscience, 15 September 1999, 19 (18) 8114-8121.

4“Dietary intakes of berries and flavonoids in relation to cognitive decline.” Ann Neurol, 2012;72:135–43.

5“Effects of Lutein and Astaxanthin Intake on the Improvement of Cognitive Functions among Healthy Adults: A Systematic Review of Randomized Controlled Trials.” Nutrients 2020, 12, 617.

6“Recent Research on the Health Benefits of Blueberries and Their Anthocyanins.” Advances in Nutrition, Volume 11, Issue 2, March 2020, Pages 224–236.

 7”Clinical Applications of Astaxanthin in the Treatment of Ocular Diseases: Emerging Insights.” Mar Drugs. 2020;18(5):E239. Published 2020 May 1.

8“Effects of Lutein/Zeaxanthin Supplementation on the Cognitive Function of Community Dwelling Older Adults: A Randomized, Double-Masked, Placebo-Controlled Trial.” Front Aging Neurosci. 2017; 9: 254.


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