Home > Products Experience > Looking after eyesight, natural protection against Age Related Macular Degeneration (AMD)
My eyesight is something that I value very highly. Without my spec's or contact lenses I have very limited vision. Looking after my eyes, in order to prevent further long-sightedness in later life, is certainly high on my agenda. Age Related Macular Degeneration (AMD) is the most common cause of blindness in people over the age of 50 in the UK and I feel thatit deserves a little attention!
The macular is the light sensitive area in the centre of the retina that controls
visual field and the ability to see colours. AMD is caused by the deterioration
of the macular. As this happens the peripheral, outer, vision remains intact
as the centre field of vision becomes slowly blurry, grey or filled with a large black
spot. Two forms of AMD exists: the dry form which develops slowly, accounting
for 90% of all cases; and the wet form which causes rapid deterioration of central
vision.
The exact causes of AMD are unknown although free radical damage, where unstable oxygen
molecules damage the eye cells, is strongly implicated. Tobacco smoke and sun
exposure can increase the level of free radicals in the body and both are a risk for
AMD. High blood pressure and diabetes are also risk factors as these conditions
can limit blood flow to the eyes.
Evidence for diet and nutrition in the prevention, and to a certain extent treatment,
of the condition is growing yearly. The latest study was published in the August
volume of the American Journal of Clinical Nutrition(1) and adds
to the growing body of research(2,3,4,5,6,7,8) suggesting that
oily fish and the long chain omega 3 fatty acids they provide, EPA and DHA (eicosapentaenoic
acid and docosahexaenoic acid), may be preventative.
This recent study(1) assessed the dietary intake data and photographic
eye evidence of 105 individuals with AMD and compared it to 2170 control individuals
(without any features of AMD). All participants were aged 65 or over.
The researchers found that eating oily fish at least once per week compared with less
than that was associated with a 50% reduced likelihood of having AMD. There
was no benefit from eating non-oily, white fish. There was also a strong significant
association between intake levels of DHA and EPA and AMD. Individuals eating
around 300mg or more of these fatty acids per day were 70% less likely to have AMD.
Two (75g) servings of oily fish, such as salmon, mackerel, sardines or trout, provides
around 500mg of DHA and EPA
The scientists are not yet recommending omega 3 supplements as the study did not investigate
whether supplements would have the same benefit as dietary sources. However,
evidence for the potential benefits of fish oil (long chain omega 3 fatty acid) supplements
is beginning to emerge, with one very recent study(5) finding
that 800mg of DHA per day over 2-4 months was associated with beneficial changes in
the macular.
Omega 3 fatty acids are incredibly important for many aspects of health (and I have
mentioned them throughout my blog postings). Including at least two portions
of oily fish per week is certainly recommended, however, many individuals in the UK
do not achieve these intakes for various reasons. A daily fish oil supplement
providing around 250mg of EPA and 250mg DHA may be something worth considering (for
general health). For vegetarians and vegans a flaxseed oil supplement providing
around 500-800mg of alpha-linolenic acid (a short chain omega 3 fatty acid which the
body can convert to the longer chain forms) daily is a good way of ensuring a daily
supply of these essential fats.
The other important nutrients worth discussing in relation to AMD prevention are the
antioxidant carotenoids lutein and zeaxanthin, naturally found in foods such as spinach,
collard greens and kale. Research data(9,10,11,12) suggests
that individuals with high dietary intakes of lutein and zeaxanthin, and high body
levels of the carotenoids, have a reduced risk of developing AMD. Supplements
of these nutrients are now widely sold and targeted at eye health. The supportive
evidence for supplementation is not yet solid. A small study(13) has
shown benefit and paves the way for larger studies. A very recent review(14) of
the currently available evidence, published last month, concluded that “A definite
association between lutein and zeaxanthin supplementation and clinical benefit has
yet to be hown; however, it may still be an appropriate cautionary measure for patients
at high risk for developing AMD”
Available ‘eye health’ supplements often contain vitamins C, E, beta carotene and
the mineral zinc in addition to lutein and zeaxanthin. The rationale behind
this comes from dietary association studies and some research evidence. If you
are considering supplements remember that they are not a substitute (more of a bonus)
for nutritious daily meals! A healthy diet, rich in a variety of vegetables
and fruits, will provide an array of antioxidant nutrients to keep the whole body
healthy, including the eyes.
(1)Augood C et al. 2008. Oily fish consumption, dietary docosahexaenoic
acid and eicosapentaenoid acid intakes, and associations with neovascular age related
macular degeneration. American Journal of Clinical Nutrition. 88:398-406
(2)Chong EW et al. 2008. Dietary omega-3 fatty acid and fish intake in
the primary prevention of age-related macular degeneration: a systematic review and
meta-analysis. Arch Ophthalmol. 126:826-833.
(3)SanGiovanni JP et al. 2007. The relationship of dietary lipid intake
and age-related macular degeneration in a case-control study: AREDS Report No. 20.
Arch Opthalmol. 125:671-679
(4)Seddon JM et al. 2006. Cigarette smoking, fish consumption, omega-3
fatty acid intake, and associations with age-related macular degeneration: the US
Twin Study of Age-Related Macular Degeneration. Arch Opthalmol. 124:995-1001
(5)Johnson EJ et al. 2008. The influence of supplemental lutein and docosahexaenoic
acid on serum, lipoproteins, and macular pigmentation. Am J Clin Nutr.
87:1521-1529
(6)Cho E et al. 2001. Prospective study of dietary fat and the risk of
age-related macular degeneration. Am J Clin Nutr. 73:209-218
(7)Seddon JM et al. 2001. Dietary fat and risk for advanced age related
macular degeneration. Arch Opthalmol. 119:1191-1199
(8)Smith W et al. 2000. Dietary fat and fish intake and age related maculopathy.
Arch Opthalmol. 112:222-227
(9)Seddon JM et al. 1994. Dietary carotenoids, vitamin A, C and E and
advanced age-related macular degeneration. JAMA. 272:1413-1420
(10)Bone RA et al. 2000. Lutein and zeaxanthin in the eyesm serum and
diet of human subjects. Experimental Eye Research. 71:239-245
(11)Bone RA et al. 2001. Macular pigment in donor eyes with and without
AMD:A case-control study. Invest Opthalmol Vis Sci. 42:234-240
(12)Gale CR et al. 2003. Lutein and zeaxanthin status and risk of age-related
macular degeneration. Invest Opthalmol Vis Sci. 44:2661-2465
(13)Richer S et al. 2004. Double-masked, placebo-controlled, randomised
trial of lutein and antioxidant supplementation in the intervention of atropic age
related macular degeneration: the Veterans LAST study (Lutein Antioxidant Supplementation
Trial). Optometry. 75:216-230)
(14)Zhao L & Sweet BV. 2008. Lutein and Zeaxanthin for macular degeneration.
Am J Health Syst Pharm. 65:1232-1238
Written by Ani Kowal
