The Role of Nutrition in AMD

Question 1

List 4 examples of antioxidants that help to prevent AMD

Answer 1

vitamins C, E, carotenoids, minerals (selenium, zinc)

Question 2

How are antioxidants thought to prevent/delay AMD

Answer 2

by reducing photo‐oxidative damage e.g. from sunlight exposure, and smoking.

Question 3

what did a systemic review inc 5 RCTs find about people who took supplements to prevent AMD

Answer 3

People who took supplements were not at decreased or increased risk of developing AMD

“Taking vitamin E or beta carotene supplements will not prevent or delay onset of AMD. The same is probably true of vitamin C and the multivitamin (Centrum Silver).”

Question 4

what does a systemic review state about multivitamins, lutein, vitamin E, zinc about slowing the progression of AMD

Answer 4

Strongest evidence came from AREDS and AREDS2

People who took supplements were not at decreased or increased risk of developing AMD

“People with AMD may experience some delay in progression of the disease with multivitamin antioxidant vitamin and mineral supplements. This finding was largely drawn from one trial, in a well nourished American population…”

Question 5

what did the AREDS study show about slowing the progression of AMD

Answer 5

Significant reduction in OR (~20% risk reduction) for development of advanced AMD with zinc + antioxidants

Effect increased (~25%) if people with early AMD excluded

“Those [people over 55 years] with extensive intermediate size drusen, at least 1 large druse, noncentral geographic atrophy in 1 or both eyes, or advanced AMD or vision loss due to AMD in 1 eye, and without contraindications such as smoking, should consider taking a supplement of antioxidants plus zinc such as that used in this study.”

Question 6

name the 3 cases of increased risk of people takin: 
beta carotene 
zinc 
and 
vitamin E

Answer 6

beta carotene: Increased risk of lung cancer
zinc: Increased genitourinary complications
vitamin E: Increased risk heart failure in people with vascular disease

Question 7

name 2 carotenoids that form macula pigment

Answer 7

Lutein (L) and zeaxanthin (Z)

Only carotenoids that concentrate in macula

Question 8

which parts of the macula do lutein and zeaxanthin each accumulate

Answer 8

Z predominates at fovea

L in parafovea

Question 9

which 5 layers of the retina are L & Z found in

Answer 9

fibres of Henle
choroid
RPE
PR outer seg
plexiform layers

Question 10

what is the peak absorption of L and Z and which type of light does this represent

Answer 10

~ 450nm
Blue Light protection

Hence MP protects against hazardous photochemical effect of short wavelength light

They also act as antioxidants

Question 11

name 3 ways in which L and Z act as antioxidants

Answer 11

Quench singlet oxygen
Scavenge free radicals
Inhibit lipid peroxidation i.e. prevent oxidative damage by reactive oxygen species

Question 12

name 4 ways in which the xanthophyll L and Z protect against AMD

Answer 12

Blue Light protection
Antioxidant
Anti-inflammatory
Vascular protection

Question 13

how does L and Z have an anti inflammatory affect

Answer 13

Thought to scavenge reactive oxygen species produced by inflammatory response

This may affect expression of pro-inflammatory molecules

Question 14

how does L and Z provide vascular protection

Answer 14

L and Z may prevent thickening of arteries and help maintain healthy retinal and choroidal vasculature

Question 15

what food is a main source of xanthophylls in diet

Answer 15

Green, leafy vegetables e.g Kale (raw)

Question 16

what provides the highest bioavailability of dietary Xanthophylls within the body

Answer 16

Xanthophylls consumed with fat more easily solubilised and processed by enzymes

2x higher plasma response to lutein supplement taken with high fat spread compared to low fat spread

Question 17

how does lutein uptake differ from plants compared to eggs

Answer 17

Esterified lutein (from plants) has 20% lower effect on serum
lutein than free lutein (found in eggs) 

Eggs has a greater affect on serum levels and it also contains fats which helps absorption

Question 18

how is the bioavailability of dietary xanthophylls affected in smokers

Answer 18

Smokers have lower levels of serum lutein and MP

Question 19

what does evidence state regarding effectiveness of xanthophyll in diet (rather than supplements)

Answer 19

High intake of L/Z and β-carotenes associated with reduced risk of developing advanced AMD, but not associated with the risk of developing early or intermediate AMD

Question 20

name the omega-3 fatty acids and fish oil found in high concentrations in brain & eye

Answer 20

Docosahexaenoic acid (DHA)
an omega-3 long chain polyunsaturated fatty acid (PUFA) 

Deficiency may initiate onset of AMD

Question 21

Name a Short chain omega-3 more prevalent in plant oils/ nuts and seeds

Answer 21

alpha-linolenic acid (ALA)

and can be converted into long chain DHA

Question 22

what is the possible benefits of long chain PUFAs and name a disadvantage it may have

Answer 22

Protection against oxidative, inflammatory, and age-related retinal
damage

PUFAs are very prone to oxidation themselves due to double bonds, and may propagate free radical damage in the retina

Question 23

what did the AREDS 2 study reveal about L and Z and omega 3 fatty acids with the progression of AMD

Answer 23

Addition of L+Z, Omega 3, or both had no additional effect on risk of progression to advanced AMD when added to AREDS formula

Omega 3 fatty acids had no beneficial or harmful effect in any subanalysis

Question 24

name 3 aspects of diet that has an increased association with AMD

Answer 24

Western diet pattern had increased association with AMD prevalence

Vegetable oils and animal fats containing omega-6 fatty acids, and red/processed meat should be consumed minimally to reduce the risk of AMD progression

High glycaemic index diets and alcohol consumption of greater than two drinks a day had increased association with AMD