Lutein for eyes and brains

Lutein is thought of as the eye vitamin. And the brain vitamin.

It is a xanthophyll carotenoid, renowned for its role in eye health, especially in filtering blue light and supporting macular pigment. Lutein is often found in combination with another xanthophyll carotenoid, zeaxanthin. Both have powerful antioxidant properties and together they help to maintain retinal tissues and preserve healthy vision and eyesight. They also help to process visual signals in the brain. In human research there has been evidence of their function in several brain regions, including those associated with cognition and motor coordination. Studies in dogs have shown the benefits of dietary antioxidants; in one canine study[1], dietary lutein was shown to stimulate humoral immune responses.

They are part of the carotenoids family that are found in large amounts in colourful vegetables – in fact, they make the bright red, yellow and orange in fruits and vegetables and the dark green in spinach and kale. “The effectiveness of carotenoids as antioxidants is also dependent upon their interaction with other coantioxidants, especially vitamins E and C.”[2].

Lutein in nature

Earlier studies to examine the impact of fish oil on the visual function in dogs found that use of fish oil supplements increased the levels of polyunsaturated fatty acids (including omega-3 and omega-6 fatty acids), which play a significant role in maintaining eye health. One test[3] showed that the visual performance of puppies fed the highest amounts of non-chain polyunsaturated fatty acids improved significantly in comparison with dogs in the low fatty acid group.

In humans, lutein has been shown to have an anti-inflammatory effect against diseases in various organs, including eye diseases, cardiovascular and skin diseases, osteoporosis and colon diseases[4]. And literature on human eye health had shown the benefits of dietary lutein, zeaxanthin and beta-carotene (and vitamins C and E). Because various combinations of antioxidants had improved visual functions in humans, one study investigated whether the same nutritional factors would have the same effect on dogs’ eyes and visual function[5]. At that time, no studies had been carried out into the effects of carotenoids on visual function in dogs and only one previous study had indicated the benefits of antioxidants on oxidative stress in sled dogs[6].

Like humans, dogs’ retinal function declines with age. Human studies have shown that lutein and zeaxanthin had improved central cone vision, which suggested that dogs could also potentially benefit from the same nutrients. After seven months, this study suggested that these antioxidants could also improve retinal function in healthy adult dogs with normal eyes. It concluded: “Antioxidant supplementation may be beneficial and effective in the long-term preservation and improvement of retinal function and the slowing of refractive error changes associated with ageing in dogs.”.

Lutein occurs naturally in fruit, cereals and vegetables and also in egg yolks, where it has higher higher bioavailability (in any event in humans) than in any other food.

Natural occurrence of Lutein and Zeaxanthin that can be included in the dog’s diet[7]

Carrots
Seaweed
Spinach
Lettuce
Kale
Green peppers
Broccoli
Carrots
Red peppers
Eggs
Egg yolk
Basil
Parsley
Corn
Durum wheat

Degradation

In studies of high-lutein wheat species included as ingredients in high-lutein functional foods for humans – such as cookies, muffins and bread – significant losses occurred during the baking process[8]. However, the “fortified” products still contained reasonable amounts, sufficient to warrant the label of high-lutein functional foods. Corn products such as cornmeal and cornflour are also potential candidates for such functional foods.

So: a worthy ingredient for training treats.

 

References:

[1] Hong Wook Kim, Boon P Chew, Teri S Wong, Jean Soon Park, Brian B.C Weng, Katherine M Byrne, Michael G Hayek, Gregory A Reinhart, Dietary lutein stimulates immune response in the canine, Veterinary Immunology and Immunopathology, Volume 74, Issues 3–4, 2000, Pages 315-327, ISSN 0165-2427, https://doi.org/10.1016/S0165-2427(00)00180-X.

[2] Young, A.J.; Lowe, G.M. Antioxidant and prooxidant properties of carotenoids. Arch. Biochem. Biophys. 2001, 385, 20–27.
[3] Kimberly M. Heinemann, Mark K. Waldron, Karen E. Bigley, George E. Lees, John E. Bauer, aLong-Chain (n-3) Polyunsaturated Fatty Acids Are More Efficient than Linolenic Acid in Improving Electroretinogram Responses of Puppies Exposed during Gestation, Lactation, and Weaning, The Journal of Nutrition, Volume 135, Issue 8, 2005, Pages 1960-1966, ISSN 0022-3166 https://doi.org/10.1093/jn/135.8.1960.
[4] Abdel-Aal, E.-S.M.; Akhtar, H.; Zaheer, K.; Ali, R. Dietary Sources of Lutein and Zeaxanthin Carotenoids and Their Role in Eye Health. Nutrients 2013, 5, 1169-1185. https://doi.org/10.3390/nu5041169
[5] Ahn YJ, Kim H. Lutein as a Modulator of Oxidative Stress-Mediated Inflammatory Diseases. Antioxidants (Basel). 2021 Sep 13;10(9):1448. doi: 10.3390/antiox10091448. PMID: 34573081; PMCID: PMC8470349.
[6] Baskin CR, Hinchcliff KW, DiSilvestro RA, et al. (2000) Effects of dietary antioxidant supplementation on oxidative damage and resistance to oxidative damage during prolonged exercise in sled dogs. Am J Vet Res 61, 886–891.
[7] Taken from: Abdel-Aal el-SM, Akhtar H, Zaheer K, Ali R. Dietary sources of lutein and zeaxanthin carotenoids and their role in eye health. Nutrients. 2013 Apr 9;5(4):1169-85. doi: 10.3390/nu5041169. PMID: 23571649; PMCID: PMC3705341.
[8]  El-Sayed M. Abdel-Aal, J. Christopher Young, Humayoun Akhtar, and Iwona Rabalski. Stability of Lutein in Wholegrain Bakery Products Naturally High in Lutein or Fortified with Free Lutein. Journal of Agricultural and Food Chemistry 2010 58 (18), 10109-10117. DOI: 10.1021/jf102400t

Important Considerations:

  • Always consult your veterinarian before making any significant dietary changes, particularly where there are pre-existing health conditions or dietary restrictions.
  • If you are feeding commercial food, check the label for ingredients before giving more. Excessive intake of any foods can have adverse effects.
  • Ensure (where possible) that you use high-quality, organic products specifically formulated for pets (or better still, human grade ingredients) to avoid any potential adverse effects.
  • Introduce new foods gradually to avoid adverse effects such as gastrointestinal upset or diarrhoea.
  • I provide nutritional information purely as a helpful guide. Nutritional information on ingredients is obtained from the US Department of Agriculture’s FoodData Central site (https://fdc.nal.usda.gov/index.html) and any nutritional information provided in recipes is based on an online calculator: calories and other information will vary based on brands, ingredients and other factors.
  • Check nutrient levels and recommendations for your dog’s weight, age and activity. For example this nutritional guideline produced by FEDIAF.
  • I am not a professional nutritionist. I am sharing recipes that I have created and tested in my kitchen and that have been tasted and approved by our doggy friends.