Plenty of us have been on diets before. To lose weight, to feel younger, to reduce blood pressure. You are what you eat, as the saying goes, and in terms of health, it couldn’t be truer. But you probably haven’t dieted for your eyes.
In the big world of nutrition, eyesight is often left behind by more mainstream concerns, such as weight loss or maintaining healthy cholesterol levels. But that doesn’t mean your eyes don’t feel the effects of diet – just the opposite, really. Your eyes are delicate organs and require a mix of nutrients to stay at their best. Vitamin B12 is among them, though researchers are still learning more about its exact role in keeping eyes well.
The Basics of B12
Chemically, vitamin B12 is a big, complex molecule. So much so, in fact, that it’s currently impossible to synthesize without the help of bacteria. As very, very few living organisms (only the aforementioned bacteria, as well as other single-celled life called archea) produce it naturally, humans have to get their fair share through diet.
Fortunately, B12 can be found in most animal products. Seafood, particularly shellfish, is an excellent source of B12, as are dairy products and eggs. Liver’s a little off the beaten dietary path for some, but it’s an incredible source of many vitamins, including B12.
For people who aren’t so eager to turn to the above options, getting sufficient amounts of B12 can be difficult. Vegans can take advantage of a wide range of B12 fortified products. Cereal, health bars, and yeast are all available in fortified forms. However, the actual amount of vitamin B12 in these foods varies and may not be enough for everyone. As a result, vegetarians and vegans are generally advised to take B12 supplements on top of their regular diet.
Effects of B12 on the Body
A solid B12 supply is crucial to having a well-oiled nervous system, as well as the creation of new blood cells. An untreated deficiency can wreak havoc across a person’s body, eventually causing severe, irreversible damage.
Weakness, pale pallor, and light-headedness are all early symptoms. These can progress to bleeding and bruising issues, as well as stomach and intestinal difficulties. Without vitamin B12, the sheaths around nerves also become damage-prone; in severe cases, neurological symptoms will eventually appear, including poor memory, difficulty thinking and concentrating, and even personality changes.
Of course, as with most vitamins, it’s possible to have too much of a good thing. Still, it takes some work to get enough B12 into your system to experience side effects – it’s virtually impossible to do so with dietary sources, and even most supplements aren’t going to put you into the danger zone.
People with certain disorders, including gout and megaloblastic anemia, should be extra cautious, as they may be more sensitive to supplements. In an otherwise healthy body, excess B12 supplements can cause nausea, raised blood pressure, and various skin problems. More worryingly, though less conclusively, tenuous links between certain cancers and B12 supplementation do exist.
Effects of B12 on Vision
We’re still a ways from understanding what parts of the visual system require B12, but recent studies have started to shed light on several uses of the vitamin.
Age-related macular degeneration (AMD) is an enormous and increasing problem for older individuals. The disease results from either a buildup of deposits at the back of the eye, or the growth of abnormal blood vessels. In both cases, sufferers lose significant portions of the central vision.
While treatment can go a long way toward stopping progression of the disease, actually catching a case of AMD isn’t easy, given how subtly it advances. While there’s no cure for AMD, there does appear to be a dietary means of slowing it down. A 2009 study found that a vitamin cocktail of B6, B12, and folic acid cut the risk of female participants’ developing AMD by 34 percent, and made them 41 percent less likely to encounter serious forms of the disease.
Optic neuropathy is among the rarer effects of B12 deficiency, but still poses a considerable threat to eyes. The optic nerve is responsible for carrying signals from the eyes to the brain; without it, even a patient with otherwise healthy eye could lose vision. B12 deficiency renders nerves, including the optic nerve, more brittle, and can cause damage to the optic nerve, resulting in decreased central vision.
In one case, B12 supplementation not only halted the vision loss of a 68 year-old patient, but actually reversed it, returning his vision to normal levels after several months. In another study, it was found that three children with autism (who rarely ate animal products and consequentially had lowered B12 levels) had B12-related vision problems, which were again addressed successfully with supplementation.
Vitamin B12 and You
So, should you be concerned about B12 deficiency? It’s actually a tricky question to answer. Younger readers with diverse diets should be getting sufficient levels without any supplementation. However, anyone following a vegetarian or vegan diet should absolutely take care to get their recommended dosage.
People over 50 should also be on guard. The body’s ability to absorb vitamin B12 from animal sources declines with age. However, most fortified foods and supplements should still be effective.
If you do need to supplement, the next question is: what sort of supplement should you take? Several forms are available and you’re likely to see liquids, pills, sub-lingual supplements, sprays, and even injections. First, avoid injections unless you’re at a hospital – they’re largely unnecessary, not to mention difficult to self-administer. Most oral forms should be fine, as long as you get them from a reliable source.