Why is lutein important?

Spoiler: the use of lutein capsules can be effective in preventing vision and some neurological disorders. The use of vitamin is considered safe and no significant side effects have been documented at high doses (although it is preferable to take lower doses for long-term use.

The miracle of vision

Concepts needed to understand the process of vision:

retina; macula; optic nerve; photoreceptors; vitamin A; lutein; zeaxanthin and natural pigments.

The optic nerve transports information from the retina to the brain (both the optic nerve and the retina are part of the central nervous system). The retina contains light-sensitive photoreceptors, whose building blocks responsible for light absorption are cartenoids.

So light enters the retina (the natural pigments responsible for absorbing light help to concentrate the photons that make up light). From there, light energy is converted into an electrical signal by a process called phototransduction – the key molecules in this process are vitamins A (retinol, retinal) and a protein called rhodopsin.

The electrical signal converted from light is in fact a computer like combination of ones and zeros – because the values of the action potential produced by light are always the same – i.e. neurons can distinguish between no signal and signal-on mode. Finally, this sequence of codes (i.e. a rapid succession of signals recording discrete values) is realised as an image when it reaches the brain.

To reach the receptors in the retina, the light must pass through the nerve cell axons. There is, however, a point (called the macula) where the nerve cells, move out of the way of the light, which means that the light can reach the receptors directly. The macula thus acts as a site of sharp vision. Degeneration of the macula results in blurred vision, or a blurring starting from the centre, the size of which depends on the progression of the condition. The macula contains high levels of lutein and zeaxanthin.

Effect of lutein – What role does lutein play in the macula?

Lutein belongs to the xanthophylls (oxygen containing carotenoids). Dark green leafy vegetables such as spinach and curly kale contain lutein^2,3. On average, an American (who eats very few vegetables) consumes roughly 1.7 mg of lutein from meals on their own per day. This is considered extremely low⁴. Lutein that enters the digestive tract can be absorbed with fat and then transported to its target sites by cholesterol⁵.

After consumption of lutein at least 0,2 μM of lutein must circulate in the body to reach the retina in sufficient amounts. Lutein has primarily pigmentary functions, it has a high light-absorbing capacity, i.e. it collects light. In the macula of the retina, another major pigment molecule is zeaxanthin (and its isomer meso-zeaxanthin). Both lutein and zeaxanthin are essential for the health of the macula and therefore our eyesight, although their effects go beyond pigment.

What other effects can lutein have?

6-20 mg lutein capsules per day have been shown to reduce the risk of visual disorders such as macular degeneration or cataracts and neurological disorders such as Alzheimer’s or Parkinson’s disease^6-12:

We have good news for those who want to understand the effects of lutein in depth.  Lutein is one of the much-researched nutritional supplements whose function is relatively well understood.

Besides its pigment functions, lutein’s main effects come from its antioxidant properties. In fact, it can be generally stated that natural pigment molecules have antioxidant properties, just think of:

• the key to photosynthesis: chlorophyll
• one of the subforms of vitamin A: beta-carotene, which gives vegetables their orange colour; or the other two subforms, retinol and retinal;
• az A-vitamin egyik alformájára: a zöldségek narancssárga színét adó béta karotinra; vagy a másik két alformára a retinolra és retinálra;
• anthocyanins, which give red and blue colours and are found in large quantities in grapes;
• and the red colour of tomato: lycopene.

Many natural pigments belong to the cartenoid group, with the exception of chlorophyll and anthocyanins.

Antioxidant as a detoxifier

Antioxidants (as anti-oxidants, anti-electron-withdrawal substances) help fight a group of toxins: reactive free radicals. It would take a biochemistry class to understand their effects, but it is enough to know that free radicals (which can be molecules or atoms) have an unstable structure. The instability makes them highly reactive, precisely because they are missing an electron (i.e. a negatively charged particle). Think of reactive free radicals as hungry dogs. Hungry dogs will roam until they find food. These ’electron-hungry’ free radicals are ready to take electrons from anywhere and if there are not enough electron donating antioxidants in our bodies, the free radicals will take electrons from the molecules that make up our cells. This can cause the cell to lose some or all of its function. Depending of which cell, which molecule and within it which atom is affected by electron deprivation; free radical damage can be a breeding ground for all existing diseases. Free radical damage is generally referred to as oxidative stress. Antioxidants are also needed to repair the damage – substances that help repair the damage are known as a type III antioxidants.

There are many compounds with antioxidant activity. Vitamin A, lutein and zeaxanthin are antioxidants that specifically protect the health of the visual organ and brain. Oxidative stress on the retina and macula (which is also a by-product of natural biochemical processes) increases the oxygen demand of the cells of the visual organ. If there is not as much oxygen as needed, the light-sensitive receptors die. This is where lutein (and other carotenoids), which make up the retina and macula, come in, as they are able to effectively remove free radicals. However, its need to be present in the human body in high concentrations 0,7 μM^13-19.

Effect of lutein as a blue light absorber

Blue light can cause eye damage 100 times more severe than orange light (the amount of damage depends on time, of course). This is why many devices (TVs, phones, computers) are fitted with blue light filters. And lutein can selectively absorb blue light, acting as a fiber to reduce visual damage caused blue light²⁰.

Effect of lutein in combination with other cartenoids

In general, lutein works better when combined with other carotenoids. In fact, lutein alone is not a strong enough antioxidant, but it can enhance the effects of other carotenoids²¹.

Some antioxidants, in descending order of potency:

Lycopene > Alpha-tocopherol > Alpha-carotene > Beta-cryptxanthin > Zeaxanthin = Beta-carotene > Lutein

So lutein should be seen as a booster that greatly amplifies the antioxidant effects the other carotenoids. However, its blue light absorbing capacity is unique and is not present to the same extent as, for example, lycopene.

Lutein side effects

The use of lutein is considered safe²⁴. One comprehensive study found no significant side effects during long-term use (5 years)²². The documented side effects mild yellowing of the skin. A single case study reported an adverse effect of high and long-term (8 years) lutein capsule consumption; a woman with a daily consumption of 20 mg lutein and a high lutein diet experienced crystal formation in both eyes²³. After stopping the consumption of lutein, the crystals disappeared in one eye and remained in the other. A 20 mg supplement of lutein may not seem like much, but many foods are high in lutein (more on this in the next chapter). The two together can result in a much higher intake of lutein and remember we are talking about 8 years of continuous high dose use. For long term use, aim for lower doses, for intermittent use higher doses are fine, as the EFSA (European Food Safety Authory) considers the dose to be safe.

For the dose of lutein capsules, EFSA has considered a daily intake of 1 mg/kg lutein and 0.75 mg/kg zeaxanthin as safe^26-28. The daily intake includes lutein from supplements and food.

Main lutein sources

As mention above, dark green leafy vegetables contain high concentrations of lutein, such as brussels sprouts and spinach.

A következő táblázat a legjobb lutein (és zeaxantin) forrásokat tartalmazza²⁹. The following table lists the best sources of lutein (and zeaxanthin)²⁹.

Which lutein supplement is recommended?

You already know that at Vitamin360 we strive for the highest quality, so our choice would be PURITAN’S PRIDE LUTEIN 40 MG capsule. As a supplement, a 10 mg lycopene capsule can further enhance the effects of lutein (or rather vica versa).

In conclusion, we would like to introduce the term vitamin L! Lutein is a much researched and proven vision-enhancing agent. Furthermore, minimal side effects have been documented from the use of lutein capsules.

Used sources:

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