Here's a question that I see frequently: what is lutein? Here, you can learn about it, its sister zeaxanthin, a related compound called lycopene and what they can do for your continued good health.
All three compounds and many more are referred to as micronutrients. Vitamins like C, D and E are called macronutrients, because they are needed in relatively large quantities, in order for the human body to be healthy.
Minimum daily requirements are established for macronutrients, although there is a great deal of debate concerning whether or not governmental guidelines, such as those set by the USDA, are sufficient. The recommended dietary allowance for vitamin C is an example.
90mg per day is believed to be enough to prevent scurvy in a healthy adult male. So, that's what the USDA recommends. But, related species that are unable to produce the vitamin consume a great deal more. Because of that, the Linus Pauling Institute suggests 400mg per day. Some alternative health practitioners recommend more.
No minimum daily requirements are set for micronutrients. There are some established, guidelines, however. For example, the USDA suggests consuming 4-8mg of lutein and zeaxanthin, combined.
So, what is lutein used for in the human body? In plants, it is used to harvest light and absorb energy from it, while helping to protect against UV damage, free radical damage and oxidative stress.
In the human body, it is one of the pigments that make up the light gathering mechanism within the eye known as the retina. It is particularly concentrated in a spot on the retina, known as the macula. Research has shown that low blood levels of the nutrient, as well as a few others, are associated with an increased incidence of age-related macular degeneration or ARMD.
So, what is lutein, a plant pigment, doing in the human eye that protects against ARMD? The answer is, as yet, unclear. Here's what we know about lutein in general.
The pigment in the macula acts as a protective barrier against free radical damage as well as oxidation, just as it does in a plant. In ARMD, extracellular material naturally present in the eye becomes hardened or oxidized and builds up on the macula.
The hardened material is called drusen. After the age of 40, most people have some drusen inside of the eye. But, in ARMD, there are many larger drusen and they are concentrated in the area of the macula. Eventually, they interfere with central vision, making it impossible to see something directly in front of you.
That should cover the questions; what is lutein and why it is a necessary part of the human diet. But, just to be clear, ARMD can and does lead to blindness, or partial blindness, in the elderly. It affects over a million Americans over the age of 65. There is no effective treatment for the condition. But, a six year study conducted by the National Eye Institute in Maryland found another answer to; what is lutein. It protects against blindness caused by macular degeneration.