“Higher levels of serum antioxidants vitamin C and lutein/zeaxanthin and higher Omega-3 oils from fish intake were associated with lower serum c-reactive protein (CRP) levels,” wrote lead author Joanna Seddon. Lower CRP levels were associated with lower risk of age-related macular degeneration (AMD). Whereas vitamin E, smoking and increased body mass index (BMI) were associated with increased CRP.
A healthy diet containing plenty of antioxidants and fish can reduce the risk of age-related macular degeneration (AMD), says this study from Harvard Medical School published April 2006 in the journal Nutrition.
AMD affects the central part of the retina called the macula, which controls fine vision, leaving sufferers with only limited sight. AMD affects over 30 million people worldwide, and is the leading cause of blindness in people over 50.
Based on data from the Age-Related Eye Disease Study (AREDS), the scientists analyzed blood samples for compounds in the blood that have been linked to inflammation and AMD.
Increased levels of C-reactive protein (CRP) and the amino acid homocysteine (HCY) have been suggested to be ‘markers' for inflammation.
Homocysteine data was available for 934 participants of the original AREDS study, and CRP measurements were available for 930. The original AREDS study population was 1026. Intake of the antioxidants, vitamin C and E, lutein, zeaxanthin, alpha- and beta-carotene, as well as fish intake, were obtained from the original data.
“For every 1000 micrograms per decilitre increase of lutein/zeaxanthin in blood, there was a two milligrams per litre decrease in CRP,” said the researchers. A 0.2 milligrams per litre decrease in CRP was also associated with more than two servings of fish per week.
Linking vitamin E with increased levels of CRP indicates that the vitamin might increase the risk of AMD, which disagrees with an earlier Dutch study that concluded: “The risk of AMD can be modified by diet; in particular vitamin E and zinc.” (Journal of the American Medical Association, Vol. 294, pp. 3101-3107)
The Harvard researchers said: “The positive association seen between higher CRP levels and increased vitamin E levels deserves additional study and may be related to known pro-oxidant effects of vitamin E with higher doses or displacement of other fat-soluble antioxidants,” It may also reflect different fractions of vitamin E tocopherols and tocotrienols used in the various studies.
Interestingly, vitamin E was linked to lower, and not higher, levels of homocysteine. No explanation for this was given by the researchers.
The Harvard study adds to a growing body of data that shows protective benefits of antioxidants, particularly lutein and zeaxanthin, against AMD. Previous research has suggested lutein intake fortifies the macula of the eye. The macula filters out blue wavelength light from the sun and artificial light, suppressing the oxidation of retinal cells that can otherwise cause degenerative eye disease.
OBJECTIVE: We investigated whether age-related macular degeneration risk factors are associated with high-sensitivity C-reactive protein (CRP) and homocysteine (HCY), systemic biomarkers for cardiovascular disease.
METHODS: Subjects with a range of age-related macular maculopathies or no maculopathy at two centers in the United States were evaluated. Risk factors and biomarkers were assessed by questionnaire, direct measurement, or analyses of blood specimens.
RESULTS: Higher levels of serum antioxidants vitamin C and lutein/zeaxanthin and higher fish intake were associated with lower serum CRP levels, whereas serum vitamin E, smoking, and increased body mass index were associated with increased CRP. Serum vitamin E, serum alpha-carotene, and dietary intake of antioxidants and vitamin B6 were associated with lower levels of plasma HCY, whereas hypertension was associated with increased HCY.
CONCLUSIONS: C-reactive protein and HCY levels are related to traditional dietary and behavioral factors associated with age-related macular degeneration.
Seddon JM, Gensler G, Klein ML, Milton RC; C-reactive protein and homocysteine are associated with dietary and behavioral risk factors for age-related macular degeneration. Nutrition 2006 Apr, 22:441-3.