Lutein is a natural carotenoid with important nutritional and physiological functions. Recent studies have shown that lutein has shown significant effects in many aspects: it can reduce the level of inflammation in patients with coronary artery disease through anti-inflammatory mechanisms; supplements rich in lutein help reduce the accumulation of phospholipid peroxides in red blood cells and delay the aging process; supplementation with lutein can also improve the visual function of patients with certain retinopathy. In addition, lutein plays a key role in the photoprotection mechanism of plants, providing a new direction for agricultural production.
Lutein is one of the more than 600 natural carotenoids that have been discovered so far. Lutein coexists with zeaxanthin in nature. It is the main component of plant pigments such as corn, vegetables, fruits, and flowers. It is contained in the chloroplasts of leaves and can transfer the absorbed light energy to chlorophyll a. It is speculated that it has a protective effect against photooxidation and photodamage. It is also the main pigment that constitutes the macular area of the human eye retina.
Lutein is a nutrient that humans can absorb when they eat fruits and vegetables on a daily basis, but the absorption rate is generally low. If you lack lutein, you can take supplements. Lutein has been added as a dietary supplement as early as 1996. In addition, excessive intake of lutein will cause an extra burden on the liver. The recommended daily dosage is about 12 mg. Now, we will interpret some of the progress made in the study of lutein function in recent years.
1. Atherosclerosis: Lutein exerts anti-inflammatory effects in patients with coronary artery disease
Lutein is a nutrient found in colorful vegetables and fruits. In a research report published in the international journal Atherosclerosis, researchers from Linkoping University found that lutein may help effectively inhibit inflammation. The relevant research results show that lutein itself may have a certain anti-inflammatory effect on the body of patients with coronary artery disease.
The researchers collected blood samples from 193 patients with coronary artery disease and measured the levels of 6 common carotenoids. At the same time, they also used the inflammatory marker interleukin-6 (IL-6) to measure the inflammatory level in the patient's blood. Lutein is the only carotenoid associated with IL-6. The higher the level of lutein in the blood, the lower the level of IL-6. Researchers found that many patients who received the best treatment according to clinical treatment guidelines still had persistent inflammation in their bodies, and the level of lutein in their bodies was relatively low.
This forced the researchers to investigate whether lutein could affect cells in the blood that are involved in the inflammatory process. They collected immune cells from the blood of patients with coronary artery disease. After in-depth analysis, the researchers found that when the cells were treated with lutein, the level of inflammatory activity of these cells was significantly reduced. The next step is to investigate whether the intake of foods rich in lutein can have a positive effect on the immune system of patients with coronary artery disease. Some dark green leafy vegetables, such as spinach, are rich in lutein.
2. Japanese scientists found that lutein can prevent the aging of red blood cells
Researchers at the Graduate School of Tohoku University in Japan recently said that they found that lutein, which is rich in green algae, has the effect of preventing the aging of red blood cells.
Researchers said that there are a large number of aging red blood cells in the blood of Alzheimer's patients, and the accumulation of phospholipid peroxide in these red blood cells is about 5 to 6 times that of healthy people. Accumulated phospholipid peroxides cause chronic hypoxia in the patient's brain tissue, worsening the condition.
According to a recent report by Japan's Yomiuri Shimbun, researchers asked six healthy volunteers to take a tablet containing about 10 mg of lutein every day. After taking it for four consecutive weeks, the lutein content in the volunteers' red blood cells increased by an average of 2.8 times the original level, while the phospholipid peroxide content in red blood cells dropped to one-third of the original level.
3. Optometry: Lutein improves visual function in some patients with retinal degeneration: a pilot study via the Internet
The study studied the use of lutein to improve the visual function of patients with retinitis pigmentosa through the Internet, and the paper was published in the journal Optometry. Participants were recruited worldwide via email. 16 participants (13 RP patients and 3 other retinitis patients) supplemented with lutein for 26 weeks (40 mg/day for the first 9 weeks and 20 mg/day thereafter). The participants tested their visual acuity on a computer screen and the expansion of their central visual field on a wall chart. Results: The participants' visual acuity increased by an average of 0.75dB, and only the patients who had previously supplemented with lutein could significantly improve their central visual field (0.55dB).
4. Study on the stress resistance of lutein
Carotenoids play an important photoprotective role in all photoautotrophic organisms. Among them, there is a special family called lutein, which is bound to the light-harvesting complex (LHCII) of photosystem II (PSII). The lutein cycle carotenoids in lutein can control the production of non-photochemical quenching (NPQ) and play a photoprotective function. In addition, light-harvesting complexes all contain lutein, which is the most widely distributed lutein and is the basic element of LHCII. In recent years, the molecular mechanism of the photoprotective effect of lutein has been gradually deepened.
Researchers at the University of Sheffield in the UK used lutein-deficient mutants (lut1, lut2) of Arabidopsis as materials, subjected the materials to abiotic stress treatment under high light intensity, drought, and low temperature conditions, and analyzed the physiological and biochemical indicators of the treated materials. Compared with the wild type (WT), the mutant lut1 is rich in violaxanthin, deoxyzeaxanthin, zeaxanthin, etc., while the mutant lut2 only increases the content of xanthophyll cycle carotenoids. When transferred to high light intensity and drought conditions for adverse stress, the mutant plants, like WT, can adapt to the new growth environment within a few days. However, after 6 days of transfer to low temperature conditions, the mutants and WT and the mutants responded differently to the new conditions. Compared with WT, the chloroplast a/b ratio and the xanthophyll cycle pool in lut2 increased significantly, and the degree of de-epoxidation and non-photochemical quenching were also enhanced.
This shows that at a suitable temperature, the structural and organizational role of xanthophyll in the light-harvesting complex can be replaced by other xanthophyll, but not at low temperatures.
5. Science: Improving photosynthesis and crop productivity by accelerating recovery from photoprotection
Researchers accelerated the adaptation of crops to excessive sunlight and overly cloudy environments by accelerating the mutual conversion between violaxanthin and zeaxanthin in the xanthophyll cycle and increasing the number of a subunit of photosystem II. Tests on tobacco plants using this system showed that their biomass production increased by about 15% under natural field conditions.