Lutein & Zeaxanthin Supplement for Diabetes Symptoms, Diabetic Retinopathy Zealut-Dena. Vitamins and supplements direct

BENEFITS OF LUTEIN AND ZEAXANTHIN SUPPLEMENTATION IN PATIENTS WITH DIABETIC RETINOPATHY

Retinopathies are characterized by inflammation and vascular remodeling and may be caused by systemic disorders. One such disorder is diabetes, which may result in the development of diabetic retinopathy, which affects >8,000 individuals in the USA each year and accounts for 12% of new cases of blindness [1].

 Although multiple carotenoid species are present in blood plasma, only lutein and zeaxanthin are able to cross the hemato-ophthalmic barrier and accumulate in the eye tissues, including the retina, where their concentration is four orders of magnitude higher than in the blood [2,3,4]. Within the retina, lutein and zeaxanthin are concentrated in the macula, where they form macular pigment. As much as 25% of their total retinal content is found in the outer segments of the rod photoreceptor neurons [5], where the light receptor rhodopsin and enzymes of its downstream signaling cascade are located.

Macular pigment (i.e., lutein and zeaxanthin) is thought to play a dual protective role by filtering out the most damaging short-wavelength irradiation (blue light and UV) and by scavenging reactive oxygen species [6, 7].  Thus, a reduction in macular pigment content would increase oxidative stress in the retina. Oxidative stress is one of the major factors in the pathogenesis of diabetic retinopathy [8]. In particular, it results in an increase in the production or activation of pro-inflammatory molecules, such as nuclear transcriptional factor-κB (NF-κB), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) [9, 10]. Activation of NF-kB promotes cell death (apoptosis) in the retina [11], which may be a major factor in the development of this disease [12].

The content of macular pigment depends on the dietary intake of lutein and zeaxanthin and follows changes in the uptake of these carotenoids with a delay of two to three weeks [13]. Thus, an increased intake of lutein and zeaxanthin could be expected to be beneficial for patients with diabetic retinopathy.

A relationship between plasma concentrations of various carotenoids and diabetic retinopathy was investigated in 111 individuals with type 2 diabetes using analysis of blood and urine and a lifestyle questionnaire [14]. This study found that the concentration of lutein, zeaxanthin, and lycopene combined, but not the concentration of α-carotene, β-carotene, and β-cryptoxanthin combined, was significantly lower in the subjects with retinopathy than in the non-retinopathy group. A higher ratio of the former group of carotenoids to the latter group was also associated with a lower risk of diabetic retinopathy, whereas a higher concentration of the latter groups was associated with a greater risk of the disease [14]. Whereas Brazionis and coworkers [14] measured concentrations of lutein and zeaxanthin together with that of lycopene, which might potentially be a confounding factor, a later study [15] reported that serum levels of both lutein and zeaxanthin (measured separately) in healthy subjects were approximately three times those in patients with nonproliferative diabetic retinopathy. An earlier study assessed the association between serum levels of two other antioxidants, ascorbic acid (vitamin C) and α-tocopherol (vitamin E), with the development of diabetic retinopathy, and found no evidence of such association [16]. Taken together, the results of these studies indicate a specific association of lutein and zeaxanthin, but not of several other antioxidants, with diabetic retinopathy.

In line with the well-documented dependence of the content of macular pigment on the plasma levels of lutein and zeaxanthin [13], two studies reported a dramatic reduction (approximately 2–2.5 fold) in the macular pigment content (measured as optical density) in patients with diabetic retinopathy in comparison with healthy subjects [17, 18].

However, correlation between the plasma levels of lutein and zeaxanthin or macular pigment content and the risk of diabetic retinopathy suggests but does not prove the causal link between these carotenoids and the disease, and by itself is insufficient to determine whether lutein and zeaxanthin supplements may delay the onset or progression of diabetic retinopathy. Yet, some studies have also reported direct beneficial effects of lutein and zeaxanthin supplementation in patients with diabetic retinopathy.

A study that involved 30 relatively young (20–30 years of age) type 1 diabetes patients examined the effect of supplementation with lutein in combination with docosahexaenoic acid (an omega-3 polyunsaturated fatty acid) for three months; the participants were subjected to a computerized perimetry test at three and six months after the onset of treatment [19]. The authors reported a significant increase in mean sensitivity and a significant decrease in short-term fluctuation in patients who received the supplement in comparison with the placebo group; the relative contributions of lutein and docosahexaenoic acid have not been assessed.

Hu and coworkers [15] found that supplementation with lutein (6 mg/day) and zeaxanthin (0.5 mg/day) for three months significantly improved visual acuity, contrast sensitivity and macular edema in patients with nonproliferative diabetic retinopathy. These data provide direct evidence that lutein and zeaxanthin supplementation at a proportion similar to that used in Zealut-Dena (12:1 vs. 10:1, respectively) and at a dosage lower than that in one Zealut-Dena capsule alleviates at least some symptoms of diabetic retinopathy.

Overall, although the details of the role lutein and zeaxanthin in protection of patients with diabetes against diabetic retinopathy remain to be investigated, the data available to date indicate that [1] both the plasma levels of these carotenoids and macular pigment content are reduced in individuals with diabetic retinopathy; and [2] lutein and zeaxanthin supplementation for several months, which is known to increase the content of macular pigment, alleviates the symptoms. This provides a clear rationale for recommending lutein and zeaxanthin supplementation in patients with diabetic retinopathy.

References

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