Dry eye disease (DED) represents a prevalent ocular surface disorder significantly impacting quality of life. Published in Frontiers in Pharmacology, researchers reviewed current advances in the therapeutic use of nutrients for DED, highlighting key components and mechanisms of action.
Overview of Dry Eye Disease
DED is characterized by either low tear production or excessive tear evaporation, leading to high osmotic pressure, inflammation, and epithelial cell damage. During the COVID-19 pandemic, the prevalence of DED surged to as high as 61%, likely exacerbated by increased visual display terminal usage and mask-wearing, which reduced blink frequency and increased tear evaporation rates. Early detection and comprehensive management of DED are essential to mitigate its economic and psychological impacts.
Nutritional Deficiencies and Dry Eye Disease
Nutritional deficiencies, particularly in polyunsaturated fatty acids (PUFAs), vitamins, and trace elements, are recognized as significant factors in the pathogenesis of DED. Extensive research has explored the impact of oral nutritional supplements, varying in composition and dosage, on the symptoms of DED. The main components of these supplements include fish oils (omega-3 fatty acids), vitamins, trace elements, and phytochemical extracts.
Key Nutrients and Their Mechanisms of Action
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Omega-3 Fatty Acids
- Mechanism: Omega-3 fatty acids reduce the production of inflammatory mediators, promoting ocular surface health and reducing DED symptoms. They support cell repair and regeneration, aiding in restoring the function of damaged corneal epithelial and lacrimal gland cells.
- Methods and results: Studies have demonstrated omega-3s significantly improve tear production, reduce tear evaporation rates, and decrease inflammation. Doses of over 2,000 mg/day have shown potential benefits but may increase bleeding risk and arrhythmias, particularly in specific populations.
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Vitamins
- Mechanism: Vitamin D supports ocular surface health and improves tear quality, while vitamin A aids in ocular surface repair.
- Methods and results: Clinical studies have shown that vitamin D supplementation improves tear film stability and reduces ocular surface inflammation. However, excessive intake of vitamins can lead to adverse effects. High doses of vitamin A may increase the risk for lung cancer among high-risk groups, and excessive vitamin E intake may raise the risk for heart failure in patients with underlying conditions.
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Trace Elements
- Mechanism: Trace elements like zinc and selenium are essential for enzyme activation and antioxidant functions, supporting cellular repair and reducing oxidative damage.
- Methods and results: Studies have found that zinc and selenium supplementation can improve ocular surface health and reduce oxidative stress. However, excessive zinc can lead to copper deficiency and anemia, while high selenium levels may negatively impact cardio metabolism and increase the risk for non-alcoholic fatty liver disease.
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Phytochemicals
- Mechanism: Phytochemicals exhibit potent antioxidant and anti-inflammatory properties, enhancing microcirculation and nutrient delivery to ocular tissues. Lutein protects the retina by filtering harmful blue light.
- Methods and results: Research has demonstrated the efficacy of phytochemicals in reducing oxidative stress and inflammation in DED patients. Long-term intake of certain phytochemicals, such as β-carotene, may increase cancer risk in specific populations, including smokers.
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Emerging Nutrients
- L-carnitine: This nutrient enhances cellular energy production and exhibits antioxidant properties, potentially improving lacrimal gland function.
- Lactoferrin: This nutrient supports tear film integrity and reduces inflammation through its antioxidant and immunomodulatory effects.
- Probiotics: The microorganisms may help modulate gut microbiota by reducing systemic inflammation and improving ocular health through the gut-eye axis.
- Coenzyme Q10: This nutrient offers protection against mitochondrial damage and oxidative stress, improving tear production and reducing inflammation.
- Spermidine: Immune balance and oxidative stress have been found to be regulated with spermidine, stabilizing the tear film and mitigating ocular surface inflammation.
- Royal jelly: This supplement may enhance tear secretion and reduce oxidative stress, promoting ocular surface health.