MyVisionTest News Archive
May 18, 2009
Fat consumption associated with AMD risk
A new study finds that fish and olive oil are protective against AMD and trans-fat increases the risk of AMD.
The evidence from published studies on the influence of dietary fat intake on the risk or the progression of AMD has been inconsistent, with some studies suggesting that higher intakes of vegetable fat and trans fat increase the risk of AMD and others not finding such risks. Some studies have also suggested that diets rich in omega-3 or fish are protective against AMD. Only 3 published prospective cohort studies evaluating the associations between dietary fat and AMD.
In this study, 6742 participants aged 58 to 69 years in 1990-1994 were recruited. Participants' nutrient intakes were estimated from a food frequency questionnaire at baseline. At follow-up from 2003 to 2006, digital macula photographs of both eyes were evaluated for early and late AMD signs.
Higher trans-unsaturated fat intake was associated with an increased prevalence of late AMD; the odds ratio comparing the highest with the lowest quartile of trans fat was 1.76. Higher omega-3 fatty acid intake (highest quartile vs lowest quartile) was inversely associated with early AMD (odds ratio, 0.85). Olive oil intake (100 mL/week vs <1 mL/week) was associated with decreased prevalence of late AMD (odds ratio, 0.48).
Trans-unsaturated fatty acids (TFA) are formed when liquid vegetable fats are hardened through a process of partial hydrogenation and are commonly found in shortenings and processed foods. Prospective epidemiological studies and case-control studies have shown TFA to increase the risk of coronary heart disease as a result of its adverse effects on lipids and possibly owing to an association with inflammation. A positive association between TFA and late AMD was found in this study. Two earlier cohort studies similarly reported TFA intake to be associated with an increased risk of AMD. In the first study of 261 participants with early AMD, TFA intake in the highest quartile compared with the lowest quartile was associated with an increased risk of AMD progression (relative risk, 2.39). In the second study, a pooled analysis of the Nurses' Health and the Health Professionals Follow-up studies, TFA intake in the highest compared with the lowest quintile was associated with an increased risk of any AMD (relative risk, 1.35).
Various studies have shown omega-3 fatty acids and fish to be inversely associated with AMD. High levels of docosahexaenoic acid (DHA), a long-chain omega-3 fatty acid, is found in the rod outer segments of the retina. These outer segments are constantly shed and turned over in the normal visual cycle. It has been suggested that deficiency of these fatty acids may initiate the onset of AMD. Omega-3 fatty acids have also been suggested to protect against oxidative, inflammatory, and age-associated damage to the retina, postulated to be key pathogenic processes in AMD development.
Olive oil is rich in vitamin E, polyphenols, and oleocanthal; the first 2 substances are powerful antioxidants, while the latter is a potent anti-inflammatory compound likened to ibuprofen. Olive oil may also be a proxy for certain healthy lifestyles that may be associated with a decreased risk of AMD. Three earlier studies have reported protective, although not statictically significant, associations between olive oil and AMD.
The investigators conclude that a diet low in trans-unsaturated fat and rich in omega-3 fatty acids and olive oil may reduce the risk of AMD.
WHAT IT MEANS TO YOU: All three of these studies found that fish or fish oil to be protective against AMD. We will have to await results of the AREDS-2 study for definitive proof that fish oil supplementation can prevent AMD progression. Meanwhile, aside from the AREDS vitamin-mineral supplement, fish consumption and fish oil supplementation has the strongest research evidence to date of any intervention designed to decrease the risk of AMD progression. The other findings from these studies, that a low glycemic index diet, olive oil, and nuts are protective and that trans-fat increases risk of AMD, fits with the widely held belief that a heart-healthy diet can have a favorable effect on AMD risk.
Read more...
Arch Ophthalmol. 2009;127(5):674-680
Tags: trans-fat, olive oil, fish, AMD
A new study finds that fish and olive oil are protective against AMD and trans-fat increases the risk of AMD.The evidence from published studies on the influence of dietary fat intake on the risk or the progression of AMD has been inconsistent, with some studies suggesting that higher intakes of vegetable fat and trans fat increase the risk of AMD and others not finding such risks. Some studies have also suggested that diets rich in omega-3 or fish are protective against AMD. Only 3 published prospective cohort studies evaluating the associations between dietary fat and AMD.
Higher trans-unsaturated fat intake was associated with an increased prevalence of late AMD; the odds ratio comparing the highest with the lowest quartile of trans fat was 1.76. Higher omega-3 fatty acid intake (highest quartile vs lowest quartile) was inversely associated with early AMD (odds ratio, 0.85). Olive oil intake (100 mL/week vs <1 mL/week) was associated with decreased prevalence of late AMD (odds ratio, 0.48).
Trans-unsaturated fatty acids (TFA) are formed when liquid vegetable fats are hardened through a process of partial hydrogenation and are commonly found in shortenings and processed foods. Prospective epidemiological studies and case-control studies have shown TFA to increase the risk of coronary heart disease as a result of its adverse effects on lipids and possibly owing to an association with inflammation. A positive association between TFA and late AMD was found in this study. Two earlier cohort studies similarly reported TFA intake to be associated with an increased risk of AMD. In the first study of 261 participants with early AMD, TFA intake in the highest quartile compared with the lowest quartile was associated with an increased risk of AMD progression (relative risk, 2.39). In the second study, a pooled analysis of the Nurses' Health and the Health Professionals Follow-up studies, TFA intake in the highest compared with the lowest quintile was associated with an increased risk of any AMD (relative risk, 1.35).
Various studies have shown omega-3 fatty acids and fish to be inversely associated with AMD. High levels of docosahexaenoic acid (DHA), a long-chain omega-3 fatty acid, is found in the rod outer segments of the retina. These outer segments are constantly shed and turned over in the normal visual cycle. It has been suggested that deficiency of these fatty acids may initiate the onset of AMD. Omega-3 fatty acids have also been suggested to protect against oxidative, inflammatory, and age-associated damage to the retina, postulated to be key pathogenic processes in AMD development.
Olive oil is rich in vitamin E, polyphenols, and oleocanthal; the first 2 substances are powerful antioxidants, while the latter is a potent anti-inflammatory compound likened to ibuprofen. Olive oil may also be a proxy for certain healthy lifestyles that may be associated with a decreased risk of AMD. Three earlier studies have reported protective, although not statictically significant, associations between olive oil and AMD.
The investigators conclude that a diet low in trans-unsaturated fat and rich in omega-3 fatty acids and olive oil may reduce the risk of AMD.
WHAT IT MEANS TO YOU: All three of these studies found that fish or fish oil to be protective against AMD. We will have to await results of the AREDS-2 study for definitive proof that fish oil supplementation can prevent AMD progression. Meanwhile, aside from the AREDS vitamin-mineral supplement, fish consumption and fish oil supplementation has the strongest research evidence to date of any intervention designed to decrease the risk of AMD progression. The other findings from these studies, that a low glycemic index diet, olive oil, and nuts are protective and that trans-fat increases risk of AMD, fits with the widely held belief that a heart-healthy diet can have a favorable effect on AMD risk.
Read more...
Arch Ophthalmol. 2009;127(5):674-680
