Dietary Vitamin C Reduces, Protects Against Cataracts

cataracts prevented with vitamin C

National Eye Institute

According to the HIH’s National Eye Institute, about half of Americans will have cataracts by the age of 80. Cataracts are also the leading cause of blindness worldwide. This is a particular problem in places like Africa and poorer island countries.

Many people begin developing cataracts in their 40s and 50s.

So what’s a cataract?

Cataracts obscure vision by clouding the lens of the eye. The lens is the clear portion of the eye, behind the pupil and iris, that allows light into the eyeball. Once light penetrates the lens, it can be imaged onto the retina on the inside back of the eyeball. The cataract cloudiness in the lens obscures or reduces the entry of light into the eyeball.

A person can have a cataract in one eye or both eyes, depending upon the cause.

The cloudiness of the cataract typically develops as a result of oxidation as a part of the aging process. In some cases, sun damage (radiation cataract) and other environmental injuries (traumatic cataract) produce cataracts earlier in life.

In most cases, a cataract causes blurred vision, light glare and light sensitivity. An early sign is seeing a halo around lights – for example around the moon.

Sometimes cataracts can develop in babies (congenital cataract) and sometimes they can be the result of glaucoma or other conditions.

Cataract surgery is the most common operation performed in Western countries. In the U.S., about 3 million cataract surgeries are done a year. In the UK, more than 300,000 procedures are carried out each year.

Vitamin C reduces cataract development

Research from the King’s College London has found that dietary vitamin C helps reduce the progression of cataracts, and probably helps prevent it.

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The researchers followed 324 pairs of female twins for ten years. They were from the Twins UK registry. The researchers examined lens photography of the twins to determine the level of opacity within their lens.

The researchers also gave each subject questionnaires to determine the amount of nutrients in their diet. The researchers found that those who had a greater consumption of vitamin C in their diet had a third less cataract progression compared to those with lower vitamin C consumption.

Those consuming more vitamin C foods also had a clearer lenses after the ten years compared to those with lower vitamin C consumption.

The study also found that ones diet along with other environmental factors influenced cataract development more than genetic factors. Genetics were connected with only a third of the cataract cases.

It so happens that the fluid within the eye will bath the lens, and this fluid is also high in vitamin C. The vitamin C helps limit oxidation from environmental conditions, including the sun. It is this oxidation that causes much of the cloudiness in the eye.

The increased consumption of vitamin C increases the vitamin C in the fluid and thus helps protect against cataract progression.

Professor Chris Hammond, an eye surgeon and the senior author of the study, stated:

“The findings of this study could have significant impact, particularly for the ageing population globally by suggesting that simple dietary changes such as increased intake of fruit and vegetables as part of a healthier diet could help protect them from cataracts.”

Dr. Hammond also discussed some of the other risk factors for cataracts:

“While we cannot avoid getting older, diabetes and smoking are also risk factors for this type of cataract, and so a healthy balanced diet and lifestyle generally should reduce the risk of needing a cataract operation.”

Vitamin C supplements don’t help cataracts

For those who want to take the short-cut and just take more vitamin C in a supplement – not so fast. Apparently, supplemented vitamin C doesn’t have the same effect on cataracts. The researchers did not find that supplemental vitamin C conveyed benefits against cataracts.

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Furthermore, the body does not produce vitamin C. We need to eat it in order to get enough.

Dr. Kate Yonova-Doing, the study’s lead author confirmed this:

“The human body cannot manufacture vitamin C, so we depend on vitamins in the food we eat. We did not find a significantly reduced risk in people who took vitamin tablets, so it seems that a healthy diet is better than supplements.”

Why dietary vitamin C is better

Vitamin C is quite a different nutrient in food. In supplemented form, vitamin C is ascorbic acid. This is synthesized in a lab. Ascorbic acid does not have the same chemical structure as foodborne vitamin C.

Ascorbic acid is typically made – believe it or not – by hydrolyzing corn syrup. This creates D-glucose, which is hydrogenated to convert it to D-sorbitol. D-sorbitol is then fermented and converted to L-sorbose. L-sorbose is then acidified using acetonation, then oxidized to form L-gluconic acid. This is hydrolyzed to form ascorbic acid. The ascorbic acid is then purified to form crystalline ascorbic acid.

One of the biggest producers of vitamin C is F. Hoffman-LaRoche, a large drug manufacturer. Their ascorbic acid process includes the use of cornstarch (likely from GMO corn) and volatile acids.

This is not what plants produce, although synthesized ascorbic acid can be legally called vitamin C. The vitamin C produced by plants contains 80 percent more compounds.

In fact, vitamin C is not a single compound. It is a complex of compounds. When a single molecule is isolated from this complex, it loses the integrity of the pure foodborne vitamin.

As such, foodborne vitamin C contains more than natural-form ascorbic acid. It also contains bioflavonoids, rutin, Factor J, Factor K, Factor P, tyrosinase, ascorbinogen and several other mineral co-factors.

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This natural vitamin C complex is extremely sensitive to heat. When exposed to heat or pasteurization, most of the natural vitamin C in a food will be denatured and will have no nutrient value.

For this reason, food producers will typically add ascorbic acid back to their juices. Why? Because the natural vitamin C is gone with pasteurization.

As discussed above, this ascorbic acid does not convey the same benefits as natural vitamin C derived from foods.

Dr. Albert Szent-Georgi, the Nobel Prize winner who discovered vitamin C once said:

“Ascorbic acid simply cannot confer vitamin activity.”

Dr. Szent-Georgi experimented with isolated vitamin C and found – as others have – that neither synthesized or isolated ascorbic acid can cure or prevent scurvy. Scurvy is famously known to be a deficiency in vitamin C – but not a deficiency in ascorbic acid.

Meanwhile, the natural vitamin C contained in one potato – a mere 20 milligrams – is enough to cure scurvy.

Dr. Szent-Georgi and others have since found that rutin and the other co-factors of vitamin C were necessary to convey the benefits of vitamin C.



Yonova-Doing E, Forkin ZA, Hysi PG, Williams KM, Spector TD, Gilbert CE, Hammond CJ. Genetic and Dietary Factors Influencing the Genetic and Dietary Factors Influencing the Progression of Nuclear Cataract. Ophthalmology. 2016 Mar 15. pii: S0161-6420(16)00114-7. doi: 10.1016/j.ophtha.2016.01.036.

Increased vitamin C in the diet help protect against cataracts. Kings College London News. Mar 24, 2016

Jensen B. Foods that Heal. Avery, 1988.

Adams C. The Ancestors Diet. Logical Books, 2014

National Eye Institute. Facts about cataract. NIH. Accessed Mar 29, 2016

The Albert Szent-Gyorgyi Papers. NIH. Accessed Mar 28, 2016

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