28/09/2020

The benefits of carotenoids for our health

Carotenoids are pigments that are naturally found in many different fruits, vegetables, algae and plants. They are powerful antioxidants, widely known for their numerous health benefits, particularly for the eyes, cardiovascular system and skin. The health benefits of carotenoids have been the subject of many scientific research studies. Nonetheless, the results are sometimes disputed. What is the current position? Overview of research by Eggersdorfer & Wyss.

Published in 2018 in the scientific journal Archives of biochemistry and biophysics, the study conducted by Eggersdorfer & Wyss [1] provides an overview of the health benefits of carotenoids identified in scientific literature.

Before we look more closely at this data, do you know why you should consume carotenoids and how best to do so?

Why and how do we consume carotenoids?

Carotenoids are a family of fat-soluble substances, (https://en.wikipedia.org/wiki/Carotenoid) mainly composed of beta-carotene, astaxanthin, lutein, zeaxanthin and lycopene. Although carotenoids are found in most fruit and vegetables, they cannot be synthesised by the human body [2]. This is why it is important to consume these substances from external sources, either in food or dietary supplements.

Carotenoids are present in most colourful fruits and in green vegetables. For example, beta-carotene is found in carrots, oranges, broccoli and spinach. Lutein and zeaxanthin are more prevalent in green cabbage, courgettes, broccoli, peas and kiwi fruit. For lycopene, tomatoes, watermelons and guava fruit are particularly recommended. Carotenoids are also found in sweet potatoes and certain types of squash. There is one exception: astaxanthin is only found in shellfish and microscopic algae (https://eurekasante.vidal.fr/parapharmacie/complements-alimentaires/carotenoide.html).

Carotenoids may also be consumed in the form of dietary supplements. For Astaxanthin, capsules are practical as we would have to consume an excessive quantity of shellfish to obtain a sufficient amount of this carotenoid. Although certain dietary supplements provide carotenoids in a general manner, others are more targeted. In particular, there are beta-carotene, lutein, zeaxanthin and lycopene dietary supplements. Natural astaxanthin has the advantage of also containing lutein and zeaxanthin.

The ideal would be to eat a diet rich in carotenoids while also consuming more targeted dietary supplements, based on specific needs.

Carotenoids and health

It is important to consume carotenoids because the human body is unable to synthesise them. But what health benefits do carotenoids offer?

Studies on the health benefits of carotenoids are sometimes contradictory. To get a clearer picture, we can look to the research conducted by Eggersdorfer & Wyss [1], which highlights the properties and roles of carotenoids identified in scientific literature.

According to this research, carotenoids may affect human health in several ways, particularly through their antioxidant properties, but also through other mechanisms.

Provitamin A: cell renewal and the immune system
Beta-carotene, also called provitamin A, is a precursor to vitamin A. Based on the body’s needs, this provitamin is converted into vitamin A, which is essential to our health. It plays an essential role in the body, particularly for our cells and the immune system.

Ocular health
Lutein and zeaxanthin are found in the human retina, and more particularly concentrated in the macula, hence their name: macular pigments. These carotenoids thus promote ocular health.

Their antioxidant properties have the capacity of neutralising singlet oxygen, offering protection against UV-induced peroxidation and reducing the formation of lipofuscin. Carotenoids also absorb blue light wavelengths, which should help to protect the eyes from photochemical lesions [4]. Other studies have shown that an additional intake of lutein/zeaxanthin can improve visual performance, particularly sensitivity to contrasts and tolerance of glare [5,6,7]. Finally, they may play a protective role in the case of age-related macular degeneration (AMD). In fact, according to a secondary AREDS2 [8] clinical trial, an additional intake of lutein/zeaxanthin may help reduce the risk of developing advanced AMD.

Sun protection
Carotenoids also have properties that protect the skin from ageing, UV-induced damage and sunburn. This is mainly due to their unique structure, composed of at least ten conjugated double bonds. This structure offers high potential for trapping reactive oxygen species, such as peroxide or singlet oxygen molecules [9]. However, the level of photoprotection obtained with carotenoids from food is lower than that achieved through the application of sunscreens. They therefore do not replace sun protection creams, but are beneficial when used together with sunscreen, as they offer protection from UV rays and help maintain healthy skin.

Cognitive performance
Although the underlying mechanisms are not clear, several carotenoids appear to affect cognitive functions. These effects seem to be linked to antioxidant activity [10]. This is particularly the case with beta-carotene, which helps maintain cognitive performance [11] and with lutein and zeaxanthin, which improve our attention span, memory and cognitive flexibility [12].

Cardiovascular health
Astaxanthin and lutein in particular seem to help prevent heart disease.

Astaxanthin is known to reduce peroxidation of low-density lipoproteins [13] and improve blood lipid profiles [14]. Moreover, it slows average blood transit time, which can be beneficial to the microcirculation.

As for lutein, its consumption and concentration in the blood appears to lead to a lower risk of coronary diseases and strokes [15].

Weight management
The antioxidant properties of carotenoids can, by reducing the overall oxidative load, have beneficial effects on weight management and obesity [16]. Moreover, based on recent discoveries, carotenoids may have a beneficial effect on adipocyte differentiation [16], which would help reduce abdominal and sub-cutaneous fat.