Diet and nutritional supplements have long been considered a resource in fighting ocular diseases and conditions such as cataracts, glaucoma, diabetic retinopathy and AMD. Adding to the literature, new research suggests the addition of certain natural foods, along with a Mediterranean diet and nutraceutical supplements, can further benefit patients and reduce the risk of vision-impairing conditions.
“Broccoli, nuts, saffron and tiger nuts are awesome single foods that can help prevent/manage ocular diseases and also can help fight against certain risk factors related to visual impairment,” the researchers wrote in their paper. “Practically all of these foods display anti-inflammatory, detoxicating, anti-angiogenic, anti-apoptotic, photo-protective, antioxidant and neuroprotective effects to some extent.”
In addition to their own original investigations, the research team from Spain analyzed 177 studies conducted from 1983 to 2021 that reviewed the benefits of natural food, the Mediterranean diet and supplements for ocular health.
The study touts the benefit of this as an important source of micronutrients and fiber, carotenes (beta-carotene and lutein), vitamins (A, B, C and E), isothiocyanates, fatty acids (linoleic acid and palmitic acid) and diverse minerals (calcium, iron, magnesium, potassium, phosphorus and sodium), in addition to amino acids. The investigative team conducted a pilot intervention study involving 14 age- and sex-matched individuals. Half the participants consumed a daily amount of 375g or broccoli, equivalent to 10g of lutein, for four weeks. At the study’s duration, the researchers found a significant increment in the macular pigment optical density in the retinographies of the right eyes in the broccoli group.
“When it comes to broccoli, we know it’s a dark leafy green vegetable, and those all have good lutein,” says optometrist and ocular nutrition expert Jeffrey Anshel, OD, of Encinitas, CA.
Saffron and AMD
Since ancient times, medicinal properties have been attributed to saffron. This spice harvested from crocus flowers contains crocin isomers, zeaxanthin, lycopene and vitamin B12, the investigators explained. In early stages of AMD, research has shown that saffron can improve visual function by reversing the damage to photoreceptors and bipolar cells caused by oxidative stress. In another investigation considered in the study, daily saffron intake improved retinal changes in patients with both dry and wet AMD.
Considering glaucoma, the researchers analyzed saffron in a mouse model of chronic ocular hypertension and found that saffron extract resulted in a reduction in both the number and signs of microglial cell activation as well as a down-regulation of the purinergic receptor P2RY12a, a marker of inflammation-related non-activated microglia. In addition, saffron also prevented the retinal ganglion cells death that occurred in chronic hypertensive eyes, suggesting the neuroprotective effect of saffron could be due to its anti-inflammatory and antioxidant properties, the authors suggested.
Chufa de Valencia
Tiger nuts aren’t actually nuts but edible tubers. The authors conducted a recent study about the role of the daily intake of tiger nuts in eye health, with the main purpose of evaluating their effects on DED. The pilot study included 20 women aged 45 to 70 who were office employees at the University of Valencia and worked daily at computers. After adding tiger nuts to their diets, the women in this group showed a noticeable reduction of the signs, symptoms and subjective sensations of DED, including reduced blink frequency and higher tear break-up time and Schirmer test results.
Walnuts’ Retinal Impact
Recent experimental evidence suggests that the main polyphenols of walnuts—ellagitannins and their metabolites—have beneficial properties against the oxidation processes of cellular components and in the inflammation pathways, in addition to positively influencing the intestinal microbiome, the authors noted.
The metabolism of ALA—a vegetable omega-3 fatty acid—gives rise to vasodilator and anti-inflammatory oxylipins, which can be the basis for a protective action on the function of capillary endothelial cells. Still, Dr. Anshel cautions that vegetable omega-3s have their limitations.
“Plant sources of omega-3s aren’t the best when it comes to metabolism compared to long chain ones such as EPA and DPA, since conversion of the shorter chain lipids aren’t efficient in men and are barely efficient in women,” Dr. Anshel explains.
The authors suggest the potential antioxidant, anti-inflammatory and neuroprotective effects of natural foods, the Mediterranean diet and nutraceutical supplements could provide a promising and highly affordable option for patients at risk of vision loss.
When asked about the numerous supplements, diets and food recommendations to better ocular health, Dr. Anshel says, “The bottom line is there is no bottom line. There is no single magic bullet, and you can’t just do one thing and affect all the different diseases in the body. It’s a combination of things. What you need to look for is a full spectrum multiple vitamin, mineral supplement, because nobody has the perfect diet. When I’m lecturing, I ask the audience, ‘How many people think they have the perfect diet?’ No hands go up, except one time a guy who was a weightlifter raised his hand, because he keeps track of all the food he eats. But that’s rare.”
Valero-Vello M, Peris-Martínez C, García-Medina JJ, et al. Searching for the antioxidant, anti-inflammatory and neuroprotective potential of natural food and nutritional supplements for ocular health in the Mediterranean population. Foods. 2021;10(6):1231.