From B12 to Omegas: What you should know about Plant-based nutrition

Underneath the common jokes about protein deficiencies lie some large misconceptions about plant-based nutrition. The most common being that you need to eat meat to survive, an idea that has been debunked over the decades by many scientists and plant-based athletes, and yet the belief prevails in society because of the clever efforts of food marketing companies.


In this article I'll break down the most common misconceptions about plant-based nutrition, and hopefully reduce any concerns you may have.


The first thing you should know is that you can get all the nutrients you need from plants, and a plant-based diet is suitable for all stages of life, including pregnancy and infancy. It uses few natural resources, causes less environmental damage, and is more sustainable than animal-rich diets. Additionally, plant-based diets are also known to reduce the risk of, end even reverse chronic diseases such as heart disease, type 2 diabetes, hypertension, certain cancers, and obesity, as well as reduce low density lipoprotein cholesterol levels [1].


People often say that a plant-based diet has to be 'well planned', but forget that ALL diets should be well planned. Nutritional deficiencies can, and do, exist in all types of diets.


So, here are the basics of what you should know about plant-based nutrition.

 
 

Protein


Ask anyone following a plant-based diet, and they will tell you that one of the most common questions they get asked is "But where do you get your protein?". But nobody ever asks where the herbivorous animals that humans eat get their protein from!


P L A N T S H A V E P R O T E I N


The largest terrestrial mammals on Earth - Elephants, Giraffes, and Rhinos, are herbivorous, and they have no issues packing on pounds of muscle. Carnivorous animals like lions prey on herbivores, so when you look at the food chain, it all comes back to plants, or 'producers'.


"Complete protein"


The claim that certain plant foods are missing specific amino acids is known to be false. All plant foods contain all 20 amino acids, including the 9 essential amino acids - amino acids that cannot be created by the body and must come from diet.

It is the proportion of these amino acids that have different distribution profiles compared to animal protein.


As you can see in the image, the only issue that may arise would be a deficiency in Lysine if your only source of protein was from nuts.

As long as your diet has a reasonable amount of variety and includes plenty of legumes, soy products, nuts, grains, and seeds, you don't need to worry about not getting enough essential amino acids [2][3].


Bar chart displaying the protein intakes of different types of diets
Daily protein intake of plant based diets are more than adequate

The amount of protein is not usually an issue either, with studies showing that vegans have a very similar total protein intake compared to other dietary groups, and with no evidence for protein deficiency in vegans in Western countries [3].

 
 

B12


B12 or cobalamin, is a vitamin necessary for the formation of red blood cells, neurotransmitter production, and heart health, among other things. It is only produced by certain types of bacteria found in soil, water, and in the guts of ruminant animals. Historically, B12 could be obtained by eating food from the ground, but as hygiene is an issue this is no longer a good source.


It is commonly thought that you need animal products to get B12, but in the majority of cases, farmed animals are given B12 supplements themselves - making them the 'middleman' between humans and B12 supplements, so it's more efficient to just take a supplement yourself [4].


Plant based sources of B12 include fortified plant milks and cereals, nutritional yeast, and spirulina, but it is recommended that everyone takes a regular B12 supplement regardless of diet to avoid deficiencies.


B12 deficiencies can take years to manifest symptoms, and can exist in omnivorous diets too, especially as absorption decreases with age. In fact, the B12 in meat is bound to proteins and is actually harder to absorb - and this is why up to 40% of older people in the UK suffer from low B12 levels [5].

 

Omegas


Omega-3s are fatty acids that are essential for good brain, skin, heart, and eye health.

The essential omega-3 fatty acid - ALA (alpha-linolenic acid) cannot be produced by the body and must be obtained from the diet from sources such as chia and flax seeds, beans, walnuts, and edamame. The body can then convert this ALA into the longer chain DHA and EPA fatty acids needed for brain health, although the conversion rates are relatively uncertain.

Microscopic image of some microalgae
Microalgae are the true producers of DHA and EPA omega-3s

The fish that people eat to get omega-3s do not actually make the omegas themselves, they accumulate it by eating microalgae that do, or by eating other fish that consume the microalgae. Similarly to animals and B12, fish are just the middlemen.

It does not make sense to eat fish to get omegas for heart health, as you would also be consuming large amounts of saturated fats and cholesterol, which both contribute largely to heart disease, as well as pollutants such as heavy metals and microplastics.


Because the conversion rates of ALA to EPA and DHA are uncertain, it is suggested that an occasional Omega-3 microalgae DHA and EPA supplement is taken, in addition to regular consumption of the ALA sources mentioned above, just to be on the safe side.

 
 

Iron


Iron is vital in the blood for the transport of oxygen around the body. Iron is obtained from the diet in two forms - heme iron and non-heme iron. Heme iron is only found in animal flesh, whereas non-heme iron is found in plant foods such as legumes, leafy greens, nuts, grains, and seeds [6] .


Although heme iron has a better absorption rate than non-heme, studies have shown heme iron to increase the risk of cancer, heart disease, and type-2 diabetes [7][8], whereas no association of heart disease with non-heme iron has been found [9].


Despite the lower absorption rate of non-heme iron, plant based diets are not associated with higher rates of iron deficiency anaemia. In fact they often contain as much, or more, iron as diets containing meat! [10].


More than enough non-heme iron can be obtained from the diet via whole grains, nuts, seeds, leafy greens, and legumes. If iron absorption is a concern of yours, it can be boosted by adding vitamin c to iron rich foods, for example squeezing lemon juice onto kale.

 

Soy


Soy is one of the most common crops grown on the planet, and for good reason. It's nutrient dense, and is a great source of calcium, omega-3, fibre, and protein, as well as phytochemicals and anti-inflammatory compounds. But many people have concerns about soy consumption and estrogen - particularly, the belief that soy consumption can cause male feminisation or increase the risk of breast cancer, because it contains estrogen-like compounds called isoflavones, or phytoestrogen. These have a very similar molecular structure to estrogen, and can interact with estrogen receptors in the body, but do not produce the same effects as estrogen, and are in-fact shown to reduce risks of breast cancer, osteoporosis, heart health, help with weight loss, and improve immune system and skin health [11][12].



Does soy cause male feminisation?


No. A recent metaanalysis of studies has shown that neither isoflavone supplements nor isoflavone-rich soy affect testosterone or estrogen levels, and isoflavones have no effect on male fertility [13]. There is also no evidence for soy consumption leading to the growth of male breast tissue [14].

 
 

Cholesterol


Cholesterol is a substance made in the liver, vital for building cell membranes, and hormones. Our bodies produces the cholesterol we need, and so it is not needed from diet [15]. In fact, the new 2020 Dietary guidelines for Americans suggests that dietary cholesterol intake is as low as possible [16], and the easiest way to do this is by avoiding animal products altogether. Studies have shown that plant based diets lower cholesterol levels more effectively than any other diet [15].

 

Fibre


Dietary fibre is very important for good gut health, prevention of bowel cancers, and reduced risk of heart disease, stroke, and type 2 diabetes. The recommended daily fibre intake for adults is 30g, but many people are not eating enough.


The best way to eat more fibre is to eat more whole plant foods, and choose wholegrain products over refined foods [17].

 

To Summarise


A whole food plant based diet has many nutritional and health benefits, and to ensure optimal health, you should consider taking these supplements:

-B12

-Vitamin D, especially if you live in higher latitudes

-Omega-3 microalgae capsules

-Iodine, if you do not consume kelp or nori sheets

 
 

References


[1] https://pubmed.ncbi.nlm.nih.gov/27886704/.

[2] https://www.health.harvard.edu/staying-healthy/getting-your-protein-from-plants

[3] https://core.ac.uk/download/pdf/265416582.pdf

[4] https://www.veganlifemag.com/debunking-myth-vegans-vitamin-b12/

[5] https://viva.org.uk/health/vitamin-b12/

[6] https://www.hsph.harvard.edu/nutritionsource/iron/

[7] https://www.bmj.com/content/357/bmj.j1957

[8] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3967179/

[9] https://academic.oup.com/jn/article/144/3/359/4615614

[10] https://www.mja.com.au/journal/2013/199/4/iron-and-vegetarian-diets

[11] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2981011/

[12] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6390141/

[13] https://pubmed.ncbi.nlm.nih.gov/20378106/

[14] https://academic.oup.com/jn/article/140/12/2289S/4630696

[15] https://www.pcrm.org/good-nutrition/nutrition-information/lowering-cholesterol-with-a-plant-based-diet

[16] https://www.pcrm.org/good-nutrition/nutrition-information/lowering-cholesterol-with-a-plant-based-diet

[17] https://www.nhs.uk/live-well/eat-well/how-to-get-more-fibre-into-your-diet/


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