One of the benefits of a high plant-based vegan diet is the protective effects against conditions such as cataracts and the gradual decline of vision with age. However, there have been several reports in the media, as well as published studies showing vegan diets can lead to deficiencies which cause blurred vision and other eyesight problems.

As we get older, it’s natural that our eyesight starts to falter, no matter what diet we’re on. But if you have a sudden onset of blurred vision, then this should be looked at by a medical professional as soon as possible.

In this article, I want to address how to avoid some of the pitfalls of a vegan diet that could lead to worsened vision over time, and some of the foods and supplements you can include in your diet that may help protect against common eyesight problems.

Deficiencies that can lead to blurred vision on a vegan diet

Below are some of the vitamin and mineral deficiencies on a vegan diet that can eventually lead to worsening of eyesight if not addressed.

Thiamine (B1) deficiency

One of the rare complications of thiamine deficiency is vision loss. Thiamine is crucial for glucose metabolism and proper functioning of the nervous system.

When thiamine is low, this can cause neuropathy and optic nerve damage. There will usually be other symptoms accompanying vision loss. If not treated early, vision loss may be permanent.

Unless your diet is very poor, it’s unlikely that blurred vision is caused by a deficiency in thiamine. But there have been case reports where thiamine deficiency was diagnosed in long-term vegans.

Which foods are high in thiamine (B1)?

Vegan foods which are high in vitamin B1 include asparagus, flaxseeds, sunflower seeds, navy beans, black beans, peas, lentils, and oats.

Vitamin B12 deficiency

One of the main symptoms of vitamin B12 deficiency is blurred vision resulting from damage to the optic nerve. However, if treated, optic neuropathy is often reversible and will result in improved vision [1].

Both vegans and vegetarians are both susceptible to B12 deficiency and should always be supplemented. B12 deficiency has been reported to be widespread among vegans and there have been case reports where blurred vision was caused in part by critically low B12 levels in long-term vegans [2].

Which foods are high in B12?

Vitamin B12 is primarily found in animal products and is sometimes fortified in non-animal foods such as milk substitutes and vegan products. However, it’s not advisable to solely rely on these for getting enough B12.

Supplementing B12 on a vegan diet is very important not only for your eyesight but your overall health.

Vitamin B2 and B6 deficiency

Deficiencies in a number of B vitamins can result in blurry vision and other eyesight problems with age. Aside from B1, vegans and vegetarians alike have been shown to be at risk of deficiencies in B2, B6, and B9 compared to omnivores [3].

Riboflavin is crucial for maintaining proper structure and function of the ocular surface and preventing damage.

Vitamin B6 has been found to be important for preventing eye diseases such as age-related macular degeneration (AMD). One of the symptoms of B6 deficiency is also blurred vision from damage to the optic nerve.

Which foods are high these B vitamins?

Vitamin B2 – Oatmeal, portabella mushrooms, almonds, quinoa, spinach, apples, beans.

Vitamin B6 –  Fortified breakfast cereals, potatoes, banana, squash, rice, nuts, raisins.

Zinc deficiency

If you’re eating a diet which contains a lot of copper (a high plant-based diet), this can lead to secondary zinc deficiency.

It’s not uncommon for many vegans to be deficient in zinc not only because they are not getting enough from the diet, but also because of anti-nutrients and copper which prevents absorption.

Long-term zinc deficiency can lead to eyesight problems such as cataracts and poor night vision [4]. Zinc is also important for acting as an antioxidant and preventing damage of UV rays.

Aside from vision problems, signs of zinc deficiency include hair loss and skin problems such as acne.

One study looking at the micronutrient status of vegans showed that 47% were zinc deficient! [5].

Which foods are high in Zinc?

Vegan foods high in zinc include hemp seeds, lentils, oatmeal, shiitake mushrooms, and whole grains.

Other reasons for blurred vision

Blurred vision may not be a result of being on a vegan diet, but can sometimes be put down to other common reasons such as the following:

• Eyestrain
• Dry eyes
• Irritation caused by chemicals
• Medications
• Eye drops
• Contact lenses
• Infections
• Trauma to the eye
• Serious causes of blurred vision: Glaucoma, Cataracts, Age-related macular degeneration, diabetic retinopathy, and other conditions.
• Age

A well-balanced vegan diet can improve eyesight

Although there have been case reports of vegans suffering from vision loss after many years of being on a vegan diet, these reports are rare and in people who are eating very poor diets and have multiple deficiencies.

By incorporating more fruits and vegetables into your diet, you are getting a lot of carotenoids such as lycopene, lutein, zeaxanthin, alpha, and beta-carotene, as well as omega 3 fats and phytonutrients which have beneficial effects in protecting eyesight.

In fact, one study showed that compared to omnivores and vegetarians, vegans had the lowest risk of cataracts. The risk of the condition in vegans was 40% lower! [6].

Vegan foods that have been known to protect eyesight include:

• Spinach
• Kale
• Sweet potatoes
• Citrus fruits
• Bilberries
• Flaxseeds
• Green tea
• Avocados

Conclusion

Aside from various vitamin and mineral deficiencies, a vegan diet does not elevate the risk of developing eyesight problems, but might actually protect against eye diseases due to the high intake of nutrient-rich fruits and vegetables.

The deficiencies on a vegan diet that can cause blurred vision include (but not limited to) vitamins B1, B2, B6, B12, and the mineral Zinc.

A vegan diet can be very restrictive because it removes certain food groups that are considered excellent sources of nutrients, which are also important for maintaining healthy vision, it’s important to supplement if needed. This is especially true for vitamin B12.

If you are experiencing blurred vision, the best thing to do is to get checked out by an eye doctor and rule out any serious causes. It may or may not have anything to do with being vegan.