Arguments for veganism

Climate change argument

• Climate change is already going to have disastrous effects on the human population. See Extinction Rebellion's take or, if you want a more household-y name, WHO's take.
• However, there is a large range in how disastrous it will be (which depends roughly on our total emissions), so reducing our emissions sooner is a great way to reduce this suffering.
• Food production makes up one-quarter (26%) of greenhouse gas emissions. Source.. Of all food production emissions, production of plant-based foods for humans make up 28%, while animal product production makes up 53%; the remaining 18% comes from supply-chain, which involves packaging, transport, food-processing and retail.
• Plant-based foods generally have far lower emissions than animal-based foods. Source.
• Food waste emissions are large; one quarter of emissions from food production are wasted, meaning we waste about a quarter of our produced food (either as consumers or during the supply-chain). Source.
• With this in mind, the biggest impact you can have on reducing emissions is by switching to a more plant-based diet. Whether you go fully vegan or not is not as important as massively reducing your consumption of animal products. I personally think the health arguments are more compelling for eliminating animal products from your diet rather than largely excluding them.
• After changing what you eat, your biggest potential for reducing emissions is in reducing supply chain emissions. You can do this by making use of food that would otherwise be wasted (perhaps by buying "odd-looking" produce from companies like Farmer's Pick) or by trying to source produce locally (by growing some of your own food, using community gardens, or sharing with your neighbours).

Reducing emissions from food production will be one of our greatest challenges in the coming decades. Unlike many aspects of energy production where viable opportunities for upscaling low-carbon energy – renewable or nuclear energy – are available, the ways in which we can decarbonize agriculture are less clear. We need inputs such as fertilizers to meet growing food demands, and we can’t stop cattle from producing methane. We will need a menu of solutions: changes to diets; food waste reduction; improvements in agricultural efficiency; and technologies that make low-carbon food alternatives scalable and affordable.
Source

Human rights argument

This assumes you believe that everyone should have access to food.

• We are already not fulfilling this right. Source
  • In 2023, for 8 billion people, one in eleven people experienced hunger, and one in five in Africa.
  • Economic access to healthy food is still low; one in three people (2.8 billion) could not afford a healthy diet in 2022. Over 70% of these people were in low-income countries.
  • It's projected that 582 million people will be chronically undernourished by 2030, with over half in Africa.
  • Extreme climate is the most common driver of malnutrition and food insecurity in countries experiencing these problems (regardless of whether these countries have access to financing directed at eradicating hunger, food insecurity and malnutrition).
• By the above points, you can improve access to the universal human right to food by switching to a more plant-based diet. See the climate change argument.
• Furthermore, increased food production required for a larger population, in addition to the un-sustainability of our current animal product demands, means that addressing food insecurity will become more challenging unless we change our demand for animal products.
  • In order to feed a projected 9.8 billion people by 2050, we will have to produce 60% more food. Source
  • We are already rapidly depleting our stocks (available, renewable sources) of food, especially meat and fish. Much of our meat and fish farming is unsustainable, meaning that our capacity to meet the current demand for animal products is having negative consequences that will eventually force us to reduce or stop. Most un-sustainability from animal agriculture is due to its large contribution to greenhouse gas emissions. Source.
• If you are also concerned with the universal right to water, and the future threat of water scarcity, moving to a plant-based diet would significantly reduce strain on our drinkable water supply.
  • Animal agriculture has huge impacts on our drinking water supply. 70% of available freshwater is used for animal agriculture (and importantly, growing plants for livestock is significantly more water intensive than growing them for direct human consumption, should you switch to a more plant-based diet). Source.
• You can reduce demand for animal products by switching to a more plant-based diet.

Nutrition

My napkin-math and sense-checking for information I've found about nourishing yourself with a vegan diet. I wouldn't read this if you're not Jack; I would read How Not to Die instead.

However, you might be interested in my math for figuring out how much ALA (an omega-3 acid in flaxseeds, chiaseeds, etc) you might need to produce all your DHA (an essential omega-3 acid that is hard to access with a vegan diet, especially if you can't access algae oil).

Terminology

• RDI = recommended daily intake
• A µg is a microgram, or one millionth of a gram.
• "Supplement" means "an oral tablet".

Summary table

Protein

RDI is 0.75g protein / kg body weight.

We need protein for energy growth, repair and maintenance of our bodies, especially our bones and muscles. Protein supports the function and healthy development of our organs like our brain, heart and liver, the antibodies in our immune system and the haemoglobin that carries oxygen in our blood.
Source

On average, vegans have higher blood protein levels than omnivores.

Vitamin B12

Information sourced from

• Vegan Food and Living
• The Conversation

Takeaways

Intake

• RDI varies from 1.5 - 4 µg. I'm going to round up the US's 2.8µg to 3 µg to make it easier.
• Many people choose to get injections, as the liver can hold up to 5mg, which is five years' worth of B12.
• B12 can only be absorbed after binding with a protein (intrinsic factor) in the stomach; if you're deficient in intrinsic factor, you can't effectively absorb B12 from food.
• Absorption declines with age. If you're over 50, you should use supplements or fortified foods even if you eat animal products (because you can't digest animal B12 easily).
• Heat can reduce B12. Microwaves destroy B12 in 2 minutes, but on a stove it would take 5 minutes of boiling to significantly destroy it.

Food intake and grams required for RDI of 3µg

Should I supplement?

• Yes! The current consensus is that you should either take a supplement or fortified foods daily.
• B12 for oral supplements comes in two forms.
  1. Cyanocobalamin. Cheap, stable, inactive. Needs intrinsic factor to absorb. Fine for most healthy people!
  2. Methylcobalamin. Expensive, unstable, active. Doesn't need intrinsic factor. If you have kidney failure, smoke or have other conditions that might affect your intrinsic factor levels.
• For deficiency, this paper still recommends intramuscular injection as the recommended route to countering B12 deficiency, for hastily bringing your B12 back up.

Should I just take B12 injections?

• No. They can be helpful as a safeguard, but I've read that your long term stores of B12 are not reliable.

The body can store B12 for two to four years without being replenished so it can take a considerable time for any problems to develop after, say, changing your diet. Having said that, you should not rely on your body’s stores of B12.

Vitamin B12 is essential for the maintenance and support of most of the vital processes that keep our body vibrant and healthy every day. Perhaps most importantly of all, it plays a vital part in the formation of red blood cells (in combination with folic acid), which help iron to work better in our bodies, and carry oxygen to every part of the body.

Every cell needs B12 for DNA replication; B12 is essential.

Symptoms of deficiency

1. Neurological changes (depression, poor memory or concentration, dementia, low mood)
2. Fatigue
3. Weakness or dizziness
4. Long term constipation
5. Loss of appetite
6. Soreness on or around the tongue, with a red appearance

Causes of deficiency

• Lack of saliva, dry mouth, ie many drugs that induce this
• Low gastric acid, ie aging
• Low intrinsic factor, ie damage to stomach lining, chronic inflammation, pernicious anaemia
• Low pancreas function

Risks of deficiency

• Anaemia can occur when a lack of B12 or folate affects our body’s ability to produce enough red blood cells.
• A lack of B12 can also lead to a raised blood levels of an amino acid called homocysteine which, at high levels, is linked to heart disease.

Comparison with animal products

• Supplemented B12 is easier to absorb than B12 animal product. In animal products, B12 is bound to animal protein, meaning it needs stomach acid to unbind it so we can absorb it. B12 in fortified foods isn't bound this way, so it's easier to absorb.
• B12 is not inherent to animal products. B12 is made naturally by bacteria in the soil, not animals. We would have gotten B12 from having more raw unprocessed foods (ie eating dirt) in the past. But now, both human and animal diets are cleaned/processed so much that it removes the natural B12, so we both need supplements. A key point is that animals are supplemented with B12, and like us, do not produce it internally.

Omega-3s (DHA, EPA, ALA)

Sources

• NIH

Intake

• The RDI for omega-3's differed a lot from what I read. The most concise figure I found was 1.6g omega-3's for males. Source
  • For pregnant women, who probably have a higher RDI for their child, it's 2.6g omega-3 fatty acids and 300mg DHA.
• The RDI for DHA, EPA and ALA specifically is more complex because your body can convert them to one another.
  • Direct DHA basically only comes from fish, though it may come from algae like spirulina. - Otherwise, the RDI for DHA and EPA combined is 250 mg for "healthy adults" (to benefit from cardiovascular disease reduction). Wikipedia, Source
  • ALA is abundant in plant sources, and can be converted into DHA and EPA.
  • To get enough DHA (250mg) by converting it from ALA (with the low conversion estimate of 2%, source), the RDI for ALA is 12.5g.
• You shouldn't take more than 2g / day of combined DHA/EPA from supplements, or more than 3g / day in total. Source
• Spirulina may be a source of omega-3's, but I wouldn't rely on it until there's more conclusive research.
  • Some 2003 research estimated 2-3g DHA / 100g spirulina (and same for EPA). Source
  • However, some 2009 research found no DHA. Its direct DHA value reports vary and don't seem very reliable as of 2024-09-26. Notably, Australian microalgae did not have detectable levels of DHA, but they did have a lot of ALA and EPA (source).

Food intake (just chia seeds, because cbf doing conversion math for other foods)

• Using my math, you can get all your DHA (via ALA conversion) with 84g chia seeds.
  • (ALA g / chia g) * (RDI chia g) = (RDI ALA g)
  • RDI ALA g = 12.5g from above
  • ALA g / chia g = 15% by the following
    • ALA g / chia g = (ALA g / chia total fat g) * (chia total fat g / chia g)
    • ALA g / chia total fat g = 50% (source)
    • 30.7 total fat g / 100g chia by Wikipedia's nutrition table
  • Solving 15% * (RDI chia g) = 12.5g ALA, we get RDI chia g = 83.4g
• Recommendation from MicTheVegan is "1.5 servings" or 54g of chia seeds a day, but this doesn't check out with my math, and doesn't provide enough ALA for DHA.
  • (ALA g / chia g) * (serving chia g) = 5.4g ALA from the video. Source
  • Using 15g ALA / 100g chia seeds from below, we get
  • (15 g ALA / 100 g chia) * (1 serving chia g) = 5.4g ALA
  • So rearranging we get 1 serving chia g = 36g, so 1.5 servings is 54g.

Benefits

• 850mg/day of combined DHA and EPA reduced heart attack incidence by 25% and 45% in sudden death. Source
• Supplementing pregnant mothers with omega-3's improved lots of brain things. Source

Contraindications

• High intake of fatty acids may be linked to increased cancer risk. I couldn't find a definition of "high intake" in mg/day for any omega-3's. This is still suggestive; it might be something else in fish. That said, let's avoid excessive omega-3's. Source

Comparison with omnivore diets

• Omega-3 is synthesised (made) by microalgae, not fish, but is accumulated in fish tissues when the fish eat the microalgae.

Iron

From my reading, you must not only take care to consume enough iron, but must take extreme care around foods that inhibit and help iron absorption. Due to the extreme impacts stated here, I think the most important dietary awareness for iron intake is to avoid inhibitors:

Choosing a drink that contains vitamin C — such as orange, tomato or grapefruit juice — around the time of your meal will increase the amount of the non-haem iron you can absorb.

In one study, 100mg of vitamin C increased iron absorption four-fold. This is roughly equivalent to what you’d get from one glass of orange juice.

Tea and coffee are considered the strongest inhibitors of iron. A cup of tea reduces iron absorption by about 75%-80%, and a cup of coffee by about 60%. The stronger you make them, the greater the effect will be.

So it’s best to avoid tea and coffee while eating and for two hours before and after the meal. This is roughly the length of time food and drinks sit in your stomach before they’re fully absorbed.

• Source

Vegetarian/vegan RDIs, which I have calculated as double that of omnivore RDIs, due to non-haem iron being absorbed less efficiently. These figures are possibly quite pessimistic.

• 22mg males
• 36mg menstruating females

Vegetarians and vegans should consume nearly twice the amount of iron as people who consume meat. This is because the type of iron in meat, poultry, and seafood known as heme iron is easily absorbed by the body. By contrast, plant-based foods provide non-heme iron, which is more difficult for the body to absorb.

• Source

Omnivore RDIs source

• 11mg males
• 18mg menstruating females

I have read that while 10-15% of typical iron intake is haem, it contributes up to 40% of absorbed iron. That suggests that 60% of absorbed iron comes from non-haem, which makes up the remaining 90% (pessimistically assuming for vegans that hame iron is only 10% of the western diet) of iron intake. So haem iron has an absorption ratio of 4, whereas non-haem iron has a ratio of 2/3. Assuming the absorption ratios don't change when you remove haem iron from your diet, that suggests that you need to make....god, I don't know. I need to talk to someone about this before I go further.

I'm calculating this table for the vegan RDIs. It's possible that you can divide these numbers by four if you have optimal iron absorption by avoiding inhibitors and adding enhancers (like orange juice) to your meals.