Nutrients of note

The nutritional quality of a plant-based dietary pattern, as with any other, is defined largely by what it includes rather than what is excluded. Therefore, nutritional considerations should always be guided by the overall dietary quality of the individual in question. In the past, plant-based dietary patterns have generally been chosen for ethical reasons, naturally leading to a focus more on what is excluded. Consequently, available research considering the nutritional adequacy of plant-based dietary patterns does not reflect the dietary status of those who choose these for health reasons (i.e. research reflects primarily low quality plant-based dietary patterns).

A recent systematic review examining nutrient intake and status of adults consuming plant-based dietary patterns noted nutrient inadequacies across all dietary patterns, including vegan, vegetarian and meat-based diets (consuming meat more than once a week, or self-defined) [1]. Intake of fiber, polyunsaturated fatty acids (PUFA), folate, vitamin C, E and magnesium were all higher with plant-based dietary patterns. While intake of several nutrients (addressed more specifically below) was found to be lower in plant-based dietary patterns, meat-eaters were noted to be at risk of inadequate intakes of fiber, PUFA, α-linolenic acid (ALA), folate, vitamin D, E, calcium and magnesium.

A whole food plant-based (WFPB) dietary pattern focuses primarily on evidence-based and healthful eating and is defined to a much greater extent by what is included. Notably, it aims to exclude sources of ‘empty’ calories present in other plant-based dietary patterns found in processed foods, and added sugars and fats especially. This naturally results in the inclusion of an abundance of highly nutrient dense plant-based foods. This means that in almost all circumstances adequate nutrition is easily obtainable without significant planning or focus on specific nutrients, unlike with other plant-based dietary patterns. Like other plant-based dietary patterns however, B12 must always be supplemented.

As a final note, it should be considered that diseases of specific nutrient deficiency are near non-existent in Australia and New Zealand, despite the fact that the vast majority of the population do not meet guidelines for the adequate intake of many of these nutrients. The clinical relevance of plant-based individuals in our societies consistently meeting these recommendations any more so than the rest of the general population is further drawn into question by the fact that these individuals consistently demonstrate better health outcomes in all areas compared to the general population (despite research being dominated by those without a health focus for their dietary choices as mentioned above).

Read on for more information about calcium, iodine, iron, omega 3/6, protein, selenium and vitamin D.

Calcium

There is little consensus on calcium requirements, and between half and near three quarters of Australians do not currently meet local recommendations [1]. Internationally there is wide variation in intake, the effect of which on clinical outcomes is unclear.

Overall evidence suggests that among adults, risk of fractures is not substantially reduced with calcium intakes greater than 500mg per day [2]. This is consistent with the finding of the EPIC-Oxford cohort that vegans who consumed over 525mg of calcium per day had the same risk of fracture as omnivores [3].

Because many foods contain modest amounts of calcium, eating a wide variety of diets with no dairy foods will include 300-400 mg of calcium [2]. Furthermore, relatively small changes in calcium absorption and excretion can neutralise a high intake or compensate for a low one [4]. Calcium absorption increases at lower dietary intakes. A dietary pattern based primarily on whole plant foods also lowers sodium intake substantially. This would be expected to result in a significant decrease in calcium excretion and lower daily requirements.

An individual following a WFPB dietary pattern that is low in sodium and who is regularly consuming dark leafy green vegetables should obtain adequate dietary calcium.

In other scenarios, plant-based individuals should be advised to include calcium-fortified products such as plant-based milk alternatives and tofu.

Iodine

Natural sources of iodine in the food supply are limited. Small amounts of iodine are found in most plant-based foods, dependent on soil iodine content. In some parts of Australia there is too little iodine in the soil, and New Zealand’s soil is naturally low in iodine. Both countries have historically relied on iodised salt as a public health measure, and recently mandated it be used in most breads.

International research suggests people do not consume the recommended amount of iodine, regardless of dietary pattern, but also that iodine consumption is significantly lower in those with plant-based diets [1,2].

On a whole foods, plant-based diet, iodine intake may be low, especially as iodised salt and commercial breads made with iodised salt are more likely to be minimised or excluded. Most will not be entirely avoiding iodised salt even if intending to, and many breads do provide a reasonable amount of iodine. However, it is unlikely that someone following a WFPB or plant-based diet will meet recommended intakes without making specific efforts to do this.

An individual following a WFPB or plant-based dietary pattern should choose iodised salt or breads containing iodised salt, and/or use seaweed as their source of iodine*. In other scenarios, including pregnancy and breast feeding a daily supplement of 150mcg is recommended.

*Iodine content of seaweed is highly variable, and intakes can easily be excessive.

Iron

Non-haem iron found in plants is less bioavailable than the haem iron found in animal products. Haem iron is associated with increased risk of cardiovascular disease, type 2 diabetes, and several cancers (although this may be due to being a marker for meat intake), whereas non-haem iron is not [1]. Overall iron intakes of people eating plant-based tend to be similar to or higher than that of omnivores [2,3]. While iron stores are consistently lower, again this also appears to be associated with lower risk of a variety of diseases [4].

Healthy plant-based dietary patterns, and particularly WFPB eating patterns contain an abundance of non-haem iron along with natural enhancers of iron absorption that will enable optimal intake in most circumstances.

In other scenarios, and in premenopausal women, legumes and other iron rich whole plant foods should be emphasised, and supplementation with chlorella, spirulina, blackstrap molasses, fortified foods or iron supplements can be considered.

Read more about iron in our article ‘Ironing out the facts’.

Omega 3/6

Both omega 3 and omega 6 are essential fatty acids, however the standard diet typically contains more than enough omega 6 yet is low in omega 3. Analysis of the 2011–2012 National Nutrition and Physical Activity Survey shows many Australians meeting omega 6 recommendations, but only 1 in 5 meeting those for omega 3 [1]. Plant-based dietary patterns are consistently found to have an even higher intake of omega 6 than omnivorous diets, so adequacy of intake is not a concern [2].

Short chain ALA omega 3 is found in a variety of plants. A plant-based dietary pattern does not contain any sources of the pre-formed long chain EPA and DHA omega 3. There is no consensus as to whether this is important. It is known that ALA can be converted to both EPA and DHA, and that while this process is often described as being ‘inefficient’, efficiency may be substantially higher in those with plant-based dietary patterns [3]. The conversion of ALA to long chain EPA and DHA is also thought to be inhibited by a high intake of omega 6 (and other factors). For this reason, some authors have suggested that people consuming a plant-based dietary pattern should aim for higher ALA intakes than the general population and make efforts to decrease omega 6 intake in order to improve conversion and their overall ratio [2].

It should be noted that the established benefits of optimal omega 3 intake pertain to cardiovascular and cognitive outcomes in the general population. A whole food plant-based diet already demonstrates substantially improved outcomes in both of these areas relative to the general population regardless of omega 3 status, and it is not clear whether an additional benefit would be observed.

An individual following a low fat WFPB dietary pattern who is regularly consuming dark leafy green vegetables may obtain adequate omega 3 and can consider adding a tablespoon of chia seed or ground flaxseed daily to ensure/increase ALA intake.

In other scenarios, a tablespoon of chia seed or ground flaxseed daily to ensure/increase ALA intake along with reducing omega 6 intake should be recommended, and a plant-based EPA/DHA supplement should be considered. Some plant-based doctors recommend this as ‘insurance’ particularly during childhood, pregnancy, breastfeeding, or older age.

Protein

Plant-based dietary patterns, particularly healthy plant-based dietary patterns and especially whole food plant-based dietary patterns contain more than sufficient protein. Intake of protein tends to be lower in plant-based dietary patterns, however a recent review reported protein intakes in a range that was nonetheless well above the recommended daily allowance [1].

An individual following a plant-based dietary pattern who consumes adequate dietary energy will consume adequate protein*.

In special circumstances, for example athletes and the elderly, higher protein whole plant foods such as legumes and whole grains can be emphasised.

* It is common for newly plant-based individuals to believe symptoms caused by an insufficiency of dietary energy are due to insufficiency of protein, so adequate energy intake should be ensured.

Selenium

Content of selenium in plant foods is variable and reflects soil concentrations of selenium. Low soil selenium levels in New Zealand mean that dietary intakes and selenium status are lower than in many other countries. While some evidence shows reduced intake of selenium with plant-based dietary patterns, generally this has been found to be close to recommended values [1]. Whole food plant-based dietary patterns include abundances of whole grains (bread, pasta, oats, rice etc.), grown in a variety of areas and oftentimes imported. Because of comparatively high levels of consumption of plant-based sources of selenium, many of which will not have been grown in low selenium areas, a whole food plant-based dietary pattern should provide sufficient selenium without supplementation.

Healthy plant-based dietary patterns, and especially WFPB dietary patterns should provide adequate selenium.

In other scenarios, addition of a Brazil nut daily can be considered.

Vitamin D

There is no requirement for dietary vitamin D, as it can be obtained from sufficient exposure to sunlight. It is unusual for requirements to be met from dietary sources regardless of dietary pattern, as there are few foods that are naturally rich sources. Mushrooms are the only plant-based food that naturally provide substantial amounts of bioavailable vitamin D (some plant-based milks have vitamin D added). Vitamin D intakes from food will therefore be lower with plant-based eating patterns [1], although research suggests other factors such as use of supplements, sun exposure, and skin pigmentation ultimately have greater influence on vitamin D status [2].

Individuals following a plant-based dietary pattern should follow the same recommendations for obtaining vitamin D from adequate sunlight as the rest of the population.

Similar to the rest of the population, vitamin D supplementation should be considered when this is impractical or the individual is at higher risk of deficiency*

* Vitamin D supplements are generally derived from lanolin, however plant-based forms of vitamin D3 are available.

Want to learn more about how WFPB nutrition may help prevent, manage or treat many chronic diseases, read on.

Introduction
1. Neufingerl N, Eilander A. Nutrient Intake and Status in Adults Consuming Plant-Based Diets Compared to Meat-Eaters: A Systematic Review. Nutrients. 2021 Dec 23;14(1):29. doi: 10.3390/nu14010029

Calcium
1. Australian Health Survey. Australian Bureau of Statistics. https://www.abs.gov.au/statistics/health/health-conditions-and-risks/australian-health-survey-usual-nutrient-intakes/latest-release. 2017.
2. Willett W et al. Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet. 2019 Feb 2;393(10170):447-492. Epub 2019 Jan 16. Erratum in: Lancet. 2019 Feb 9;393(10171):530. doi: 10.1016/S0140-6736(18)31788-4
3. Appleby, P., Roddam, A., Allen, N. and Key, T. (2007). Comparative fracture risk in vegetarians and nonvegetarians in EPIC-Oxford. European Journal of Clinical Nutrition, 61(12), 1400–6. doi: 10.1038/sj.ejcn.1602659
4. Vitamin and mineral requirements in human nutrition, 2nd ed. World Health Organization. World Health Organization. https://apps.who.int/iris/handle/10665/42716 2005

Iodine
1. Fallon N, Dillon SA. Low Intakes of Iodine and Selenium Amongst Vegan and Vegetarian Women Highlight a Potential Nutritional Vulnerability. Front Nutr. 2020;7. doi:10.3389/fnut.2020.00072
2. Weikert C, Trefflich I, Menzel J, et al. Vitamin and Mineral Status in a Vegan Diet. Dtsch Arzteblatt Int. 2020;117(35-36):575-582. doi:10.3238/arztebl.2020.0575

Iron
1. Hooda J, Shah A, Zhang L. Heme, an essential nutrient from dietary proteins, critically impacts diverse physiological and pathological processes. Nutrients. 2014 Mar 13;6(3):1080-102. PMID: 24633395; PMCID: PMC3967179. doi: 10.3390/nu6031080
2. Sobiecki JG, Appleby PN, Bradbury KE, Key TJ. High compliance with dietary recommendations in a cohort of meat eaters, fish eaters, vegetarians, and vegans: results from the European Prospective Investigation into Cancer and Nutrition-Oxford study. Nutr Res. 2016 May;36(5):464-77. doi: 10.1016/j.nutres.2015.12.016
3. Rizzo NS, Jaceldo-Siegl K, Sabate J, Fraser GE. Nutrient profiles of vegetarian and nonvegetarian dietary patterns. J Acad Nutr Diet. 2013 Dec;113(12):1610-9. doi: 10.1016/j.jand.2013.06.349
4. Haider LM, Schwingshackl L, Hoffmann G, Ekmekcioglu C. The effect of vegetarian diets on iron status in adults: A systematic review and meta-analysis. Crit Rev Food Sci Nutr. 2018 May 24;58(8):1359-1374. doi: 10.1080/10408398.2016.1259210

Omega 3/6
1. Meyer BJ. Australians are not Meeting the Recommended Intakes for Omega-3 Long Chain Polyunsaturated Fatty Acids: Results of an Analysis from the 2011-2012 National Nutrition and Physical Activity Survey. Nutrients. 2016 Feb 24;8(3):111. doi: 10.3390/nu8030111
2. Burns-Whitmore B, Froyen E, Heskey C, Parker T, San Pablo G. Alpha-Linolenic and Linoleic Fatty Acids in the Vegan Diet: Do They Require Dietary Reference Intake/Adequate Intake Special Consideration? Nutrients. 2019 Oct 4;11(10):2365. doi: 10.3390/nu11102365
3. Welch AA, Shakya-Shrestha S, Lentjes MA, Wareham NJ, Khaw KT. Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the product-precursor ratio [corrected] of α-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort. Am J Clin Nutr. 2010 Nov;92(5):1040-51. doi: 10.3945/ajcn.2010.29457

Protein
1. Mariotti F, Gardner CD. Dietary Protein and Amino Acids in Vegetarian Diets-A Review. Nutrients. 2019 Nov 4;11(11):2661. doi: 10.3390/nu11112661

Selenium
1. Bakaloudi DR, Halloran A, Rippin HL, et al. Intake and adequacy of the vegan diet. A systematic review of the evidence. Clin Nutr. 2021;40(5):3503-3521. doi: 10.1016/j.clnu.2020.11.035

Vitamin D
1. Bakaloudi DR, Halloran A, Rippin HL, et al. Intake and adequacy of the vegan diet. A systematic review of the evidence. Clin Nutr. 2021;40(5):3503-3521. doi: 10.1016/j.clnu.2020.11.035
2. Chan J, Jaceldo-Siegl K, Fraser GE. Serum 25-hydroxyvitamin D status of vegetarians, partial vegetarians, and nonvegetarians: the Adventist Health Study-2. Am J Clin Nutr. 2009 May;89(5):1686S-1692S. doi: 10.3945/ajcn.2009.26736X