Age-related macular degeneration (AMD) is one of the most common retinal diseases that lead to vision loss. AMD is associated with vascular pathology and the accumulation of extracellular material. AMD is the third leading cause of visual impairment in the world. Among the adult population 45-85 years old, 8.7% suffer from AMD.

Two types of age-related macular degeneration

  • Dry form (85-90%) is characterized by dysfunction of the retinal pigment epithelium, loss of photoreceptors, and retinal dystrophy.
  • Wet form (10-15%) is characterized by the proliferation of blood vessels, accompanied by retina hemorrhage and retinal pigment epithelium detachment.

Laser photocoagulation and vascular endothelial growth factor inhibitors stop the abnormal proliferation of blood vessels in AMD. However, these treatments remain ineffective in the long term.

Risk Factors for Visual Impairment

  • Smoking increases oxidative stress and reduces antioxidant levels by releasing free radicals that lead to visual impairment. Oxidative stress is involved in the pathogenesis of AMD.
  • Excessive alcohol consumption is associated with cataracts and short-term vision problems.
  • Dietary saturated fat intake is associated with an 80% increased risk of AMD.
  • Low consumption of carotenoids and omega-3 fatty acids is associated with accelerated progression of AMD.
  • High intake of calcium and iron supplements is associated with the risk of developing glaucoma. However, the intake of calcium and iron from food, on the contrary, protects against glaucoma.
  • Exposure to bright sunlight or ultraviolet radiation can cause damage to the retinal pigment epithelium, which is also seen in AMD.
  • An inactive lifestyle increases the risk of AMD by 70%.
  • Overweight is associated with increased levels of inflammatory cytokines, high levels of oxidative stress, and hyperlipidemia, which lead to the progression of AMD.
  • Genetic predisposition.

Protective Factors

  • Antioxidants, vitamins, and minerals such as zinc and copper reduce the risk of AMD. Some micronutrients can reduce inflammation and oxidative stress and reduce the pathological growth of blood vessels.
  • Omega-3 fatty acids prevent vision loss in AMD.
  • High consumption of fish, vegetables, and fruits reduces the risk of AMD.
  • Regular physical activity. The protective effect of exercise can be explained by a reduction in systolic blood pressure, white blood cell count, and body mass index, factors associated with the onset of AMD. Physical activity also reduces systemic inflammation and endothelial dysfunction, which are involved in the pathogenesis of AMD.

How Dietary Calcium Affects Age-Related Macular Degeneration

Taiwanese scientists conducted a study involving 5,227 people and analyzed what minerals participants get from food and how these minerals affect the risk of AMD. Minerals include magnesium, copper, zinc, sodium, calcium, and selenium.

Members:

  • 391 people with AMD, 70 ± 11 y.o.
  • 4728 people without AMD, 58 ± 12 y.o.

The optimal dietary intake of magnesium, copper, zinc, calcium, and selenium is as follows:

  • For men: Mg – 420 mg, Cu – 900 mcg, Zn – 11 mg, Ca – 1000 mg, Se – 55 mcg.
  • For women: Mg – 320 mg, Cu – 900 mcg, Zn – 8 mg, Ca – 1200 mg, Se – 55 mcg.

Participants with AMD ate significantly fewer minerals, including calcium, magnesium, potassium, and selenium. Participants with AMD had higher serum glucose and calcium levels and higher levels of C-reactive protein.

Initial data analysis showed that dietary calcium, magnesium, zinc, sodium, and selenium were significantly associated with AMD. However, after adjusting for age, gender, race, laboratory parameters, smoking, and medical history, dietary calcium alone was still significantly associated with AMD.

Dietary calcium significantly reduces the risk of AMD. However, there was no relationship between serum calcium concentration and AMD.

One mechanism that explains the protective effect of calcium is that dietary calcium is responsible for modifying vitamin D and serum parathyroid hormone levels. The parathyroid hormone regulates calcium metabolism. Indian scientists found that people who consumed > 520 mg of calcium daily had lower serum parathyroid hormone concentrations. Low serum parathyroid hormone levels are associated with retinal vessel diameter and a low risk of retinal microvascular disease. In patients with AMD, the length and diameter of retinal vessels were significantly reduced.

Conclusion

Inadequate dietary intake of calcium increases the risk of AMD in the elderly. High calcium content in the diet reduces the risk of AMD and protects against vision loss.

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