The Vegetarian Resource Group Blog

The age of Information is also the age of misinformation – Claims regarding vegetarianism and vitamin A

Posted on August 28, 2014 by Nina Casalena, The VRG Blog Editor

By Riccardo Racicot

In today’s age of information we are able to access the answer to almost any question we have within seconds. With access to the Internet and search engines at our fingertips, thanks to smartphones and laptops, any inquiry or dispute can be settled immediately. Unfortunately this is a double-edged sword. While we may have swift access to information, there is no assurance that it is accurate. This is especially true regarding nutrition information. There are countless resources on the Internet claiming to be legitimate sources, many of which have an agenda. These sources include advocacy groups promoting a particular agenda and who may posture legitimate sounding ideas as science when the background information is not there. This, I believe, perpetuates myths and poor quality information, directly resulting in stigma and misinformation towards vegetarianism.

About a month ago I happened to see a Facebook post from one such advocacy group claiming “Carrots are not a source of vitamin A. Vitamin A is found exclusively in animal foods.” While I am not a vegetarian, this type of misinformation concerns me because it may dissuade people from pursuing a healthy vegetarian lifestyle. Claims such as this are unfounded and based on a poor understanding of science and I would like to dispel some common myths surrounding vegetarianism and vitamin A here.

Claim: Vitamin A is found exclusively in animal foods

Technically this is correct. However it’s highly misleading. Vitamin A in its complete form, retinol, is only found in animal products; however, the precursors to vitamin A are found in a plethora of fruits and vegetables including carrots, mango, spinach and sweet potatoes. When we eat foods containing these precursors, such as beta-carotene, our body converts them to vitamin A. The rate of conversion from beta-carotene to retinol varies widely depending on a number of factors and ranges from a 3.8:1 to 28:1 ratio, meaning it requires somewhere between 3.8 to 28 units of retinol precursors to make a single unit of retinol.¹ Because of the variation in the conversion rate of carotenoids to retinol, daily vitamin A requirements are expressed in micrograms (mcg) of Retinol Activity Equivalents (RAE), a unit that takes into consideration the ease of absorption depending on the source of vitamin A. Many plant-based sources actually have a higher RAE than their animal-based counterparts, with the major exception being beef liver. While plant-based foods are not a source of complete vitamin A, they provide our bodies with the necessary building blocks to meet our vitamin A requirements.

Source: U.S. Department of Agriculture, Agricultural Research Service. 2013. USDA National Nutrient Database for Standard Reference, Release 26. Nutrient Data Laboratory Home Page, http://www.ars.usda.gov/ba/bhnrc/ndl

Claim: Vegetarians cannot obtain enough vitamin A to meet daily requirements

In the United States, vitamin A deficiency is rarely an issue, so much so the newly proposed FDA Nutrition Facts label will not require the listing of vitamin A.² This is no exception for vegetarians. For adult males the Recommended Dietary Allowance (RDA) is 900 mcg RAE while for women it is 700 mcg RAE. These amounts of vitamin A are easily achievable by a few servings of yellow-orange fruits and vegetables and/ or dark leafy greens. For example a simple raw salad of spinach, Swiss chard, carrots, tomato and bell peppers is enough to fulfill the daily requirements for a woman. The salad, along with an additional whole, raw mango fulfills the requirements for a man.

Source: U.S. Department of Agriculture, Agricultural Research Service. 2013. USDA National Nutrient Database for Standard Reference, Release 26. Nutrient Data Laboratory Home Page, http://www.ars.usda.gov/ba/bhnrc/ndl

Other common sources of vitamin A that could help vegetarians meet their daily requirements include:

Source: U.S. Department of Agriculture, Agricultural Research Service. 2013. USDA National Nutrient Database for Standard Reference, Release 26. Nutrient Data Laboratory Home Page, http://www.ars.usda.gov/ba/bhnrc/ndl

Claim: Breastfeeding infants of vegetarian parents are at risk for vitamin A deficiency

Breastfeeding infants born to mothers with poor dietary habits who lack essential nutrients are those who are at risk for deficiency. A child being breastfed by a vegetarian mother is only at risk for vitamin A deficiency if the mother is not consuming adequate vitamin A. During lactation, the RDA for vitamin A increases to 1,300 mcg RAE per day. Again, this is easily achievable with several servings of yellow-orange fruits and vegetables and/or leafy greens. Consuming plant-based food containing vitamin A precursors allows the mother to convert them to vitamin A and pass them along to the infant through breast milk. Lactating mothers with adequate intakes of vitamin A precursors will provide their infants with adequate amounts of vitamin A.³

Claim: Vegetarian children are at risk for vitamin A deficiency

According to a recent study less than 5% of all children ages 2-8 years old have a daily intake of vitamin A less than what is recommended by the USDA.⁴ Along with this a 2002 study of children ages 11-18 years old showed vegetarians consume almost 1500 more units of vitamin A on average than their non-vegetarian counterparts.⁵ There is little risk of vitamin A deficiency in vegetarian children who regularly eat yellow-orange fruits and vegetables and/or leafy greens.

Claim: Fat is required for vitamin A absorption

Vitamins are generally classed into two categories; fat soluble and water soluble. Water soluble vitamins include the B vitamins and vitamin C. As their name implies, these vitamins dissolve in water. Vitamins A, D, E and K are fat soluble vitamins and dissolve in fat. Because of this, fat needs to be consumed along with the source of vitamin A for proper absorption. However, it has been shown that the amount of fat needed to promote vitamin A absorption is minimal at only 3-5 g of fat.⁶⁷ Consumption of a fat source, such as avocado has been shown to increase absorption of beta-carotene from carrots 6.6-fold as compared to eating carrots alone.⁸ Other fat sources that could potentially increase absorption include oils such as olive oil, salad dressing, nuts, and nut butters.

Conclusion

Adequate vitamin A intake is readily achievable by those practicing a vegetarian diet. A vegetarian diet offers the opportunity for adults and children to meet vitamin A needs through consumption of vitamin A precursors from fruits and vegetables and for breastfeeding infants through their well-nourished mother’s milk. Consumption of fat along with vitamin A and its precursors enhances absorption, with the amount of fat required being minimal. As with all types of diets, fulfilling the requirements for essential nutrients should be considered when making meal choices.

Riccardo Racicot recently graduated from the University of Massachusetts Amherst with a bachelor’s degree in Nutrition.

1. Haskell MJ. The challenge to reach nutritional adequacy for vitamin A: ß-carotene bioavailability and conversion—evidence in humans. Am J Clin Nutr. 2012;96(5):1193S-1203S.
2. U.S. Food and Drug Administration. Proposed Changes to the Nutrition Facts Label.http://www.fda.gov/food/guidanceregulation/guidancedocumentsregulatoryinformation/labelingnutrition/ucm385663.htm. Updated 2014. Accessed 08/05, 2014.
3. The importance of [beta]-carotene as a source of vitamin A with special regards to pregnant and breastfeeding women. Eur J Nutr. 2007;46(9).
4. Berner LA., Keast DR., Bailey RL., Dwyer JT. Fortified foods are major contributors to nutrient intakes in diets of US children and adolescents. J Acad Nutr Diet. 2014;114(7):1009-1022.
5. Perry CL, McGuire MT, Neumark Sztanier D, Story M. Adolescent vegetarians: How well do their dietary patterns meet the Healthy People 2010 objectives? Arch Pediatr Adolesc Med. 2002;156:431–437.
6. Roodenburg, AJ, Leenen R, van het Hof KH, Weststrate JA, Tijburg LB. Amount of fat in the diet affects bioavailability of lutein esters but not of alpha-carotene, beta-carotene, and vitamin E in humans. Am J Clin Nutr. 2000;71:1187-1193.
7. Jayarajan P, Reddy V, Mohanram M. Effect of dietary fat on absorption of [beta] carotene from green leafy vegetables in children. Indian J Med Res. 2013;137(5).
8. Kopec RE, Cooperstone JL, Schweiggert RM, et al. Avocado consumption enhances human postprandial provitaminA absorption and conversion from a novel high-β-carotene tomato sauce and from carrots. J Nutr. 2014;144(8):1158-1166.

1 to “The age of Information is also the age of misinformation – Claims regarding vegetarianism and vitamin A”

  1. MJ says:

    Very well-written article. It was all interesting, but I found the fat issue quite interesting. I wonder if soy milk has enough fat to help with absorption of vit A (and D, E, and K). I.e. what is the minimal amount of fat we need to absorb these vitamins, and is that ridiculously easy to achieve with basic foods such as the fat in bread, soymilk, or other common ingredients? (ok, I’ll admit I get a lot of fat from my vegan chocolates). Don’t get me wrong, I love avocados – but this year, they were very expensive when not in season. I think I will now look up how much fat a glass of soy has, my veganic bread (One Degree is the brand available where I live), etc.



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