In the news: Omega-3 Status in AMD offspring with ‘Foveal Dip’; Med Diet Linked to Lower Risk of Sjögren’s

Background: The Early Biomarkers of AMD Study

Macular pigment is composed of the dietary carotenoids lutein and zeaxanthin, and the lutein metabolite meso-zeaxanthin. Reduced central macular pigment optical density (MPOD) is a potential bio-marker for age-related macular degeneration (AMD), and poor intake of lutein, zeaxanthin as well as fish (a source of omega-3 fats) are reported AMD risk factors.

In addition, a central dip collectively termed the ‘foveal macular pigment dip” or FMPD is considered a further risk; high foveal MPOD is protective, while individuals with FMPD are at increased risk of AMD.

Children of parent(s) with AMD have a 45% lifetime risk of also developing the disease. Researchers from Scripps Institute and University of California at Irvine recently investigated the prevalence of FMPD among healthy but high-risk AMD offspring, and evaluated the association of FMPD with genetic risk and carotenoid and omega-3 fatty acid status(1).

Methods and Results

Macula pigment 3D topography was evaluated using specular reflectance in 130 Caucasian men and women, mean age 62.8 years. Buccal genetic cheek swab, circulating serum dietary carotenoids and long-term red blood cell (RBC) omega-3 fatty acid status, as well as common secondary clinical structural and vision function parameters were obtained.

Forty one percent (41%) of those with a parental history of AMD presented with FMPD. These offspring were about 4 years younger than those without FMPD (controls; P = 0.012) and had thinner foveas (P = 0.010). There were no differences in gender, BMI, % body fat, visual acuity or contrast sensitivity between those with and without FMPD.

The % of the omega-3 fatty acid DHA in RBC membranes was reduced in FMPD offspring vs. control offspring (P = 0.04). The Omega-3 Index--a measure of long-term EPA and DHA in blood--was significantly decreased in the FMPD group (P = 0.03).

Conclusions

According to the authors, the % of FMPD in AMD offspring is nearly twice that reported for the general population. Although offspring with FMPD had similar AMD genetic risk, they had significantly reduced % RBC membrane omega-3 fatty acids and thinner foveas compared with those without FMPD. “Our data support the importance of essential fatty acids as an independent AMD risk factor”, the authors stated.

Of clinical interest, all study participants were free of three of the major predisposing factors associated with the foveal dip phenomenon: advanced age, smoking and a clinical diagnosis of AMD.

Med Diet Lowers Risk of Sjögren’s

UK researchers report(2) that higher adherence to the Mediterranean (Med) diet is associated with a lower likelihood of developing primary Sjögren’s syndrome (SS), the autoimmune disease characterized by oral and ocular dryness and fatigue.

Participants were classified into SS and non-SS (dry eye and mouth with no presence of autoimmune disease). A Med diet score (MDS) was calculated based on dietary intake data.

A higher total MDS was associated with 19% lower odds of SS per one unit of MDS, corrected for energy intake, BMI, sex, age, duration of symptoms and smoking status. Fish intake was Med diet component most strongly linked with lower likelihood of SS.

The authors hope these findings will stimulate further research, larger studies, and dietary intervention trials if warranted.

References

1. Rutledge GA, et al. Foveal macular pigment dip in offspring of age-related macular degeneration patients is inversely associated with omega-3 index. BMC Ophthalmol. 20:473, 2020
2. Machowicz A, et al. Mediterranean diet and risk of Sjogren’s syndrome. Clin Exp Rheumatol. 38 (Suppl 126) S216-21, 2020.