Mechanical eye schematic - by Doug Cook RD

Best Foods To Improve Eyesight

Eye schematic 300x204 - Best Foods To Improve Eyesight

 

So many things impact our health. The environment, our habits, including the foods we eat, sleep, activity, and more all influence the health of our bodies including our eyes and long-term health such as vision.

 

It’s very easy to take good vision for granted, and most of us do. More people are worried about losing their vision than they are about getting a cancer diagnosis and yet the vast majority of people don’t know what the most common forms of vision loss are nor do they know what steps they need to take to preserve their eyesight.

 

As a dietitian-nutritionist, I am very excited about the role food and nutrition have on eye health and vision. What you eat and drink directly affects the structure of your eyes and, in turn, structure influences function.

 

The premise behind getting more eye foods into your diet is that these foods, and the nutrients they’re rich in, are the nutrients essential to optimal eye health. Paying attention to this will go a long way to preserving your long-term vision.

Eye anatomy overview

It’s amazing that despite how much you use your eyes in daily life, if you’re like most people, you have no idea about the anatomy of your eye nor do you understand how the optical system works. The good news is, you don’t need to be an optometrist or ophthalmologist to grasp how a healthy diet that includes targeted eye foods and supplements will serve your vision well.

 

Nutrition has a direct role in overall eye health but especially with the lens, retina, and macula, and optic nerve.

Cornea

The cornea is the clear front surface of the eye that allows light to enter and helps focus this light on the back of the eye. The cornea is located directly in front of the iris and is so transparent that you may not be able to see it.

Lens

The lens plays a critical role in focusing light rays onto the retina and forming sharp images. The transparent structure sits behind the iris. The lens has the remarkable ability to adjust very quickly to focus on objects at different distances. The shape of the lens must change in order to form a sharp image.

 

The lens is held in place by the ciliary muscles. The muscles contract and relax to help change the shape of the lens to focus on objects at varying distances. This process is known as accommodation.

Retina & macula

The retina is the thin layer of light-sensitive tissue lining the inner surface of the back of the eyeball. It contains two types of special cells called photoreceptors.

 

Rods detect motion, function well in low lighting conditions, and provide black and white vision. Cones provide color vision and central vision, and function well in medium and bright lighting conditions. At the center of the retina is the macula, where the cones are concentrated.

 

These photoreceptor cells convert the light that is focused on the retina into electrical impulses that are transmitted to the brain.

Vitreous chamber

The vitreous chamber or vitreous body is located behind the lens and in front of the optic nerve. It is filled with vitreous humour, a clear, jelly-like substance that helps maintain the shape of the eyeball.

Optic nerve

The optic nerve is a bundle of approximately 1 million nerve fibers that transmit the electrical impulses formed by the retina to the visual cortex of the brain. It is made up of ganglionic cells or nerve cells. The nerve begins at the optic disk, a small structure where the ganglion cell output fibers (called axons) converge and leave the eye.

Basic Eye Anatomy 300x300 - Best Foods To Improve EyesightCommon eye diseases

The leading causes of blindness and low vision in developed countries are primarily age-related eye diseases such as age-related macular degeneration, cataract, diabetic retinopathy, and glaucoma. Overt, clinical vitamin A deficiency is a leading cause of blindness in the third world and developing countries and is a major public health issue.

Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a chronic disease of the central part of the retina; “macula”. AMD is associated with aging and results in diminished sharp and central vision. This is important as central vision is needed to see objects clearly and for common daily tasks such as reading and driving.

 

AMD is the leading cause of largely preventable blindness in developed countries in those over the age of 55. It’s estimated that a whopping 2 million Canadians (5.2% of the population) have some form of AMD. And with more and more Canadians living longer, the number of those living with AMD is expected to increase significantly. There are two forms of AMD” “dry” and “wet”.

Dry AMD

Dry AMD is when the macula thins over time as part of the aging process, gradually blurring central vision. Dry AMD occurs when cells in the macula begin to break down, causing thinning of the macula and gradually, decreased vision. In addition, the retina (where the macula is found) is unable to rid itself of its metabolic waste, called lipofuscin. As lipofuscin accumulates, it’s referred to as drusen which eventually blocks the normal vision of the retina.

 

The dry form is more common and accounts for 70–90% of cases of AMD and it progresses more slowly than the wet form. Over time, as less of the macula functions, central vision is gradually lost in the affected eye. Dry AMD generally affects both eyes.

Wet AMD

Wet AMD is when abnormal blood vessels behind the retina start to grow under and into the macula through breaks in the membrane that separates the choroid from the retina. Ultimately, wet AMD leads to blood and fluid leakage. Bleeding, leaking, and scarring from these blood vessels cause damage and lead to rapid central vision loss. An early symptom of wet AMD is that straight lines appear wavy.

 

Neither dry nor wet AMD causes total blindness, only a decrease or loss of central vision. This greatly impacts their quality of life and people with AMD may notice changes in their ability to read, see street signs, or see fine details on a person’s face; however, they are able to walk and move around safely.

 

The risk factors for AMD include age (over 55), smoking, family history of AMD, UV light exposure (sunlight), metabolic issues such as high blood pressure, diabetes, overweight, and obesity, and diets high in sugar and refined carbohydrates and poor in antioxidants, especially the carotenoids lutein and zeaxanthin (1, 2, 3, 4, 5, 6, 7, 8). The most significant risk factor appears to be smoking.

Cataracts

A cataract is a clouding (loss of transparency) of the eye’s lens and is the leading cause of blindness worldwide, and the leading cause of vision loss in the United States. Cataracts can occur at any age because of a variety of causes and can be present at birth.

 

As we age, the lenses in our eyes become cloudy (the proteins become oxidized and their structure changes), causing a gradual blurring of vision along with reduced night vision. Other symptoms include reduced near vision, glare, and the need for more light for reading.  Many aren’t aware that they have cataracts because the change in their vision is so gradual. Cataracts are most common in people over the age of 60.

 

Risk factors for cataracts are age, smoking, steroid medications, UV light exposure (sunlight), family history, and diets high in sugar and refined carbohydrates. Diets rich in lutein and zeaxanthin may slow the formation of cataracts (8, 9, 10, 11, 12).

Dry Eye Syndrome

Dry eye syndrome is a fairly common eye condition. Even though it doesn’t typically cause significant vision like cataracts or AMD, dry eye syndrome does have an impact on overall eye health, and the symptoms can affect a person’s quality of life.

 

The tear film is composed of three layers: 1. aqueous (water), 2. lipid (oil), and 3. mucous. Those with dry eye have a disruption in the balance of these three layers. The degree and symptoms of dry eye vary considerably. With mild dry eye, it can feel like something is in your eye or a burning sensation. With more moderate and severe cases, dry eye syndrome can cause eye pain and profound watering of the eye (especially in cooler weather or when it’s windy).

 

Risk factors for dry eye include the environment, eyelid diseases (blepharitis or meibomianitis), an imbalance of omega-6 to omega-3 ratio, systemic autoimmune diseases such as lupus, Sjogren’s syndrome, rheumatoid arthritis, contact lens and excessive computer use (13, 14, 15).

Eye nutrients for better vision

Eye nutrients are a group of nutrients that are beneficial to eye health. Research suggests that eye nutrients may reduce the risk of eye diseases, either working on their own or in conjunction with other nutrients in a synergistic manner. Besides nutrients, the glycemic load also seems to impact eye health.

 

The glycemic load basically refers to not only the total amount of carbohydrate in the foods you eat but also the rate at which these ‘carbs’ are digested. This is because rapid and prolonged increases in blood sugar increase inflammation and damage through a process called glycation. Glycation is the process when sugars (that come from the digestion/breakdown of dietary carbohydrate) attach to fats and proteins in various tissues including the eyes (16).

 

Eye nutrients work by reducing oxidation (damage to tissue structures like cellular fats, proteins, DNA, etc. An example of oxidation is a rusty nail, water and oxygen react (oxidize) with the iron in the nail and it rusts). Another mechanism of eye nutrients is their ability to reduce excessive inflammation. Many of the best eye nutrients are antioxidants.

Lutein and zeaxanthin

Lutein and zeaxanthin (LZ) are carotenoids like beta-carotene is. LZ are pigments that accumulate in both the brain and optic nerve and retina. Your body cannot make LZ so you must get from your diet. In your eye, lutein is converted into zeaxanthin, and in turn, zeaxanthin is converted into meso zeaxanthin which is concentrated in the macula, the center of the retina where light is concentrated and is responsible for sending the incoming light onto the optic nerve.

 

In the eye, LZ absorbs blue light and UV light protecting both the lens and especially the retina, from the damaging effects that light exacts over time. Consuming LZ-rich foods, as well as supplements increases the concentration of LZ in the lens and retina. There’s no RDA (Recommended Dietary Allowance) for LZ but studies suggest that a minimum daily average intake of 6 mg per day offers benefits. It’s estimated that the average daily intake of LZ is about 2 mg per day.

 

Studies show that LZ can improve visual function in those with AMD, as well as reduce the risk of AMD from developing in the first place. LZ also protects against age-related cataracts and cardiovascular disease and breast cancer to boot (17, 18, 19).

Vitamin C

Ascorbic acid, a.k.a. vitamin C, is found in fruits, vegetables and because its water-soluble, cannot be store in the body in any meaningful way. Getting a daily supply of it is crucial. Diets high in vitamin C are associated with lower rates of AMD in the elderly. Vitamin C also reduces the risk of cataracts (20, 21, 22). Vitamin C can also be obtained from supplements.

Omega-3 fatty acids

The main omega -3 fats that are talked about in nutrition are ALA (alpha-linolenic acid), EPA (eicosapentaenoic acid), and DHA (docosahexaenoic acid). In reality, there is a third omega 3 that is part of the EPA and DHA grouping that’s always overlooked, and that is DPA.

 

Whenever you’ve heard about the health benefits of omega 3 fats, it’s really EPA, DPA, and DHA that are responsible. ALA is a precursor to the others but because humans can’t convert ALA to EPA, DPA, and DHA efficiently or effectively, it’s important to get the latter three from food (fish, seafood, and omega 3 enriched eggs) or supplements (23, 24, 25).

 

The longer-chain omega 3s EPA, DPA, and DHA are potent anti-inflammatory fats. Consumption of fish and seafood and consequently greater intakes of omega 3s can decrease the risk of AMD. Omega 3s are also therapeutic for those with dry eye syndrome (26, 27).

Vitamin D3

Vitamin D is the nutrient most people are at risk of being deficient in because there are no appreciable food sources except for fatty fish, milk, and eggs. We evolved to create all the vitamin D we need via the action of sunlight on our skin. The problem is, humans are scattered all over the planet and unless you live near the equator year-round, you won’t have the opportunity to make vitamin D. That’s because you can only make it from the sun when the UVB index is 3 or higher and you’ll need to get sufficient exposure, studies show that lots of us are missing the mark (28).

 

Because foods are low in vitamin D, supplementation is needed to achieve the optimal blood levels that experts suggest is around at least 100-125 nmol/L (40-50 ng/L) (29). The current RDA of 600 IU per day will not achieve this, most adults will need at least 4000 IU (100 mcg) of vitamin D3 to get to 100-125 nmol/L (30, 31, 32).

 

Higher blood levels of vitamin D are associated with a decreased risk of early AMD and may delay progression to advanced AMD (33, 34, 35).

Vitamin E

Vitamin E is not just alpha-tocopherol, it’s a family of vitamers that include four tocopherols and four tocotrienols. All are important and meeting your requirement for these eye-healthy nutrients is easier than you think as they’re found in nuts, seeds, eggs, and abundant in fruit oils like olive and avocado oil.

 

While it’s true other vegetable oils have vitamin E (at least in the form of alpha and gamma-tocopherol), they are also very high in the omega-6 fat linoleic acid which we already get too much of. Because it’s best to avoid vegetable oils, you shouldn’t rely on them to get your vitamin E.

 

Vitamin E, like other antioxidants, may decrease the risk of cataracts and AMD (36, 37, 38).

Zinc

Zinc is unique in that your body doesn’t have any way to store it as it does with other minerals such as iron, calcium, magnesium, or phosphorus for example. Therefore, it’s important to eat foods rich in zinc on a daily basis.

 

Zinc from diet and supplements has been shown to protect against AMD. Specialized antioxidant supplements with high doses of zinc (80 mg) such as the AREDS/AREDS2 (39) are shown to decrease the risk of progression from intermediate to advanced macular degeneration by 25% (40, 41).

 

A word of caution with zinc. Long-term, high-dose supplementation can lead to a copper imbalance. If you use a multimineral supplement, be sure it contains both zinc and copper. The amount of zinc used in the ARED studies was 80 mg per day which is considered to be a very high dose since the recommended intake for adults is 8-11 mg/day. Intakes like that will need to be balanced with copper (42).

 

The recommended upper level of intake of zinc from both supplements and food is 40 mg per day so it’s best not to exceed that unless under medical supervision (43).

Astaxanthin

Like alpha and beta carotene, lutein, zezxanthin, and lycopene, astaxanthin is a carotenoid. Astaxanthin is responsible for impairing a specific colour to foods as other carotenoids do. Astaxanthin is responsible for the red-orange and pink colour of salmon and shrimp.

 

While not as well researched as lutein and zeaxanthin, astaxanthin is getting some attention for its role in ocular health (44).  A two-year study investigating the effects of an antioxidant supplement (including 4 mg of astaxanthin per day) on AMD symptoms found that active treatment resulted in clinically meaningful stabilizations and improvements in visual acuity, contrast sensitivity, and visual functioning, indicating that antioxidants may help to both delays the progression of AMD and improve visual performances (45).

Glycemic load

The glycemic load is a measure of the glycemic index of a particular food in relation to its carbohydrate content in a given serving. The concepts of glycemic load and the glycemic index is confusing for most and I for one feel it should never have left the lab but rather stay in the realm of research.

 

The bottom line as far as dietary carbohydrate is concerned is, diets that have a lot of refined carbohydrates (white rice, bread, pasta, bagels, buns, fruit juices, sweetened beverages like iced tea) and/or a lot of added sugars (found in essentially all processed foods) negatively impacts eye health over the long run. Diets with a lot of these types of foods and beverages increase the risk of AMD and cataracts (46, 47, 48).

What about meso zeaxanthin?

Meso zeaxanthin is one of the three carotenoids (along with lutein and zeaxanthin) that accumulate in and therefore make up the macular pigment; a yellow pigment that absorbs harmful blue light protecting the photoreceptors from damage and improves visual performance. A macula that has a low macular pigment density (MPD) (a.ka. a “thin macula”) means it doesn’t have a lot of lutein, zeaxanthin, and meso zeaxanthin which increases the risk of AMD.

 

In your retina, meso zeaxanthin is formed from the enzymatic conversion of zeaxanthin, and zeaxanthin is likewise enzymatically derived from lutein. Historically, lutein and zeaxanthin have gotten all the attention but we now know that their sibling meso is just as important (49). Because there aren’t any meaningful food sources of meso zeaxanthin to speak of and there isn’t a lot of research (for now) to support the notion that meso zeaxanthin should be taken over dietary sources of lutein and zeaxanthin, many feel that taking about meso muddies the discussion on nutrition ocular health.

 

But that doesn’t mean meso zeaxanthin can’t help or doesn’t have a supporting role.  Studies show that getting all three carotenoids together increases the MPD more so than just eating LZ-rich foods does. And not surprisingly, take all three in supplemental form also increases the MPD more than taking a lutein or lutein and zeaxanthin supplement on their own (50, 51). Fortunately, there are several supplements on the market now that offer all three carotenoids (LZM) making it easy to get all three.

 

Eye sanning 300x200 - Best Foods To Improve Eyesight

Foods to improve eyesight

Leafy green vegetables

  • Aim to include several (3-4) servings (1 cup raw, or 1/2 cup cooked) per week

Leafy green veggies, such as kale, spinach, dandelion greens, romaine lettuces, radicchio, leaf lettuce, arugula, Swiss chard, rapini (broccoli rabe), collard, mustard, and turnips greens are great sources of lutein and zeaxanthin, beta-carotene, vitamin C, and vitamin E.

 

The carotenoids lutein and zeaxanthin are absorbed best when leafy greens are eaten with fat and even better when cooked. But don’t worry, it’s still good to get a variety of raw and cooked foods. If raw, like in a salad, be sure to include a source of fat like olive oil versus just a vinaigrette. When eating them cooked, eat them with a fat source like the fat in meat, fish, or poultry or added fats like butter or olive oil.

Eggs

  • Aim to have 6 eggs a week (no need to worry about dietary cholesterol ).

Eggs (e.g. egg yolks) are a great source of highly absorbable lutein and zeaxanthin. They also contain vitamin E, zinc, small amounts of vitamin D, and omega-3 fatty acids. You can even get more omega 3 if you buy omega 3 enriched eggs.

 

If you are an egg eater, and you make the switch to omega 3 enriched, you can increase your total omega 3 intake without making any changes to your eating behaviour. Of course, omega 3 enriched eggs won’t have as much omega 3s as fatty fish does so don’t skip on the fish or seafood.

Nuts and seeds

  • Have one serving of nuts and/or seeds daily. Serving sizes vary depending on the nut or seed, so aim for about 2-4 Tbsp per day

Nuts and seeds such as almonds, walnuts, cashews, sunflower seeds, pumpkin seeds, pistachios, hazelnuts, pine nuts, pecans, dry-roasted soybeans, and peanuts (not technically nuts) are rich in vitamin E and zinc.

Coldwater, fatty fish

  • Aim to have several (2-3) servings of 100 g (3.5 oz) per week.

Fatty fish such as sardines, trout, salmon, herring, and mackerel, are the best sources of omega 3 fats (EPA, DPA, and DHA), as well as vitamin D3, zinc, vitamin A, astaxanthin (in salmon and trout). Any fish or seafood will have eye-healthy omega 3s so eat whatever you like, don’t try to eat things that don’t float your boat. The key is to be consistent as your body needs a steady supply of these essential fats.

 

There’s a lot of concern and misinformation about the mercury content of fish but you needn’t worry about that if you choose to eat fish and seafood that are also rich in selenium; this mineral prevents mercury toxicity. For more information on this topic, check out my post on whether or not you should worry about the trace amounts of mercury in fish.

Orange peppers

  • Aim to have 2 full peppers per week (spread out, e.g. 1/2 a pepper four times a week)

All bell peppers are great sources of vitamin C but orange peppers in particular are also rich in zeaxanthin and vitamin E.

Green vegetables

  • Aim to include several (3-4) servings (1/2 cup cooked) per week

Other green vegetables such as Brussels sprouts, broccoli, peas, and green beans also contain lutein and zeaxanthin, vitamin C, beta-carotene, and vitamin E. The nutrients in these vegetables are also absorbed better when cooked and eaten along with some fat, either the fat naturally in foods like fish, seafood, meats, and poultry are added after cooking (butter, olive oil).

Oysters & shellfish

  • Aim to have a couple (1-2) of servings of 75 g (2.5 oz) per week

Oysters are the best source of zinc and they, as well as other shellfish, are also a good source of omega-3 fatty acids. One of the easiest ways to include oysters, assuming you like them, is to have smoked ones on hand. They can easily be added to salads, sandwiches, or on crackers.

Beef & pork

  • Aim to have a couple of servings of 100 g (3.5 oz) per week

Both of these meats are one of the best sources, second to oysters. of zinc

Liver

  • Aim to have a few (3-4) servings of 100 g (3.5 oz) per month

Livers of any kind (beef, pork, chicken, etc.) are a great source of zinc and the original, best-known eye-health nutrient, vitamin A. It’s important to note, that beta and alpha-carotene ARE NOT the same as vitamin A (retinol/retinal). Some of the beta & alpha-carotene that you eat will be converted to vitamin A but not everyone makes this conversion efficiently, it’s best to include food sources of vitamin A in your diet.

Kiwi & bell peppers

  • Aim for several (4-5) servings (1 kiwi fruit, 1/2 cup of peppers), per week

These two foods are one of the best sources of vitamin C

Best eye supplements

There’s no shortage of eye health supplements on the market. Many will contain the very vitamins and minerals outlined above, plus or minus the preferred omega 3 fats EPA and DHA. There are also stand-alone, eye health, carotenoid-based supplements that contain lutein, or lutein, and zeaxanthin. There are now meso zeaxanthin supplements as well that boast all three retina and macular-loving pigments (LZM).

Macushield

Macushield is one of the first supplements of its kind. Formulated in 2006 where it was launched in the UK. It’s now sold in many countries around the world and it’s where I get mine via Amazon Canada.

 

MacuShield, as their website states, is derived from marigold flowers, and it combines the three macular carotenoids lutein, zeaxanthin, and meso-zeaxanthin (LZM). As mention, we get, and it’s easy to get, lutein and zeaxanthin from our diet alone but meso zeaxanthin is much rarer. There are trace amounts in some fish and seafood but there’s no reliable source that makes supplementation ideal and preferred.

 

They have a few different formulas including MacuShield Original that has LZM in a ratio of 5:1:5 or 10 mg of lutein, 2 mg of zeaxanthin, and 10 mg of meso zeaxanthin that the manufacturer states makes up the macular pigment. The original version also comes in a chewable format and vegetarian formula.  MacuShield Gold has, in addition to LMZ, the added nutrients from the AREDS formula: zinc, vitamin C, vitamin E, and copper.

Macuhealth

MacuHealth is the North American version of MacuShield. Both supplements’ formula has been clinically proven to rebuild and improve the macular pigment density (MPD) (improves the concentration of these crucial carotenoids in the macula of the retina). By improving the MPD, patients had both enhanced visual performance and improved support in the treatment and prevention of age-related macular degeneration (52, 53, 54, 55, 56, 57).

 

Getting eye health supplements that have all three carotenes helps to improve MPD more so than lutein or lutein and zeaxanthin alone. For these reasons, it’s likely best to include supplements like MacuShiled, MacuHealth as part of your eye health strategy.

 

Alternately, you could choose one of two newer products on the market such as Blue Light Protection Formula by Webber Naturals, or their formula with added omega 3 fats for dry eye, Blue Light & Dry Eyes Protection Formula. Another similar product is Lutein 20 Blue Light Defence by CanPrev. These other formulas have less meso zeaxanthin, 2 mg per dose versus 10 mg found in MacuShield and MacuHealth.

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Bottom line

Maintaining good eye health and vision should be part of your healthy living and healthy aging strategy.

 

Not only will it help to maintain a good quality of life, maintaining your eyesight will help you to engage in other health-supporting behaviours just as activity and exercise, shopping and cooking, engaging in activities that support brain health like continued learning or doing hobbies that bring you joy. Maintaining your eyesight also helps to reduce the risk for one of the most common risk factors of morbidity and mortality: falls.

 

While most will rank eyesight as being one of the most important things to have and maintain, most also are unaware of the leading causes of impaired vision and what steps are needed to maintain their vision for life.

 

Whether you have an existing eye condition or are trying to maintain healthy eyes, amping up your nutritional game is crucial if you want to have your best possible vision now, and well into your older age.

 

Doug Cook RDN is a Toronto based integrative and functional nutritionist and dietitian with a focus on brain and mental health and antiaging nutrition. Follow me on FacebookInstagram, and Twitter.

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