5.2 Vegetarian & Vegan Diets

In the previous section, we discussed the importance of increasing vegetable intake in the diet to support alkaline load, as well as fibre and beneficial nutrient intake. It’s now becoming increasingly popular to remove meat from the diet (vegetarian diet) or to entirely exclude all animal products (vegan). This is done for desired health benefits, as well as the welfare and environmental concerns surround animal husbandry and the global impact of the meat industry.

There are also variations within vegetarian and vegan diets including:

• Pollotarian – eat chicken but no other meat.
• Pescartarian – eat seafood and fish but not poultry or meat.
• Ovo-vegetarians – eat eggs.
• Ovo-lacto-vegetarians – eat dairy and eggs.
• Flexitarian – plant-based diet with occasional meat.

Vegans exclude all animal by-products including eggs, dairy and honey. Some vegans also take the ethical stance to exclude certain types of fruits and vegetables that have been pollinated by swarms of worker bees that are shipped across farms in to mass pollinate crops, e.g. avocado and broccoli.

But, if we put aside the ethics and environmental impact of animal farming, is excluding a food group that contains important nutrients, such as iron, zinc, Vitamin B12 (all in meat) and calcium (from dairy), beneficial to health?

The research seems to show that for many people, avoiding (or at least drastically reducing) meat in the diet may well benefit health benefit in the long-term. Recent studies show a significant protective effect of a vegetarian diet versus the incidence and/or mortality from ischemic heart disease (−25%) and incidence from total cancer (−8%). In the same recent meta-analysis, the vegan diet conferred a significant reduced risk (−15%) of incidence from total cancer.

Please read the following articles as part of this course content:

• Vegetarians live longer and healthier.
• Vegetarians have lower cancer risk.
• Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies.

It’s not just the nutrient content and alkaline load of vegetables that makes them stand out as the major health benefitting food group. Recent research shows significant associations between consumption of vegetable-based diets and increased levels of faecal short-chain fatty acids (SCFAs). As we discussed in Module 3, Part 1, SCFA production and gut microbiome composition is key to our health linking all parts of the clinical imbalances model– from neurological to immune to digestive health. Please revise your notes in this area and read the following short articles that make part of the course content:

• High-level adherence to a Mediterranean diet beneficially impacts the gut microbiota and associated metabolome.
• Dietary fibre and bacterial SCFA enhance oral tolerance and protect against food allergy through diverse cellular pathways.

Therefore, encouraging patients to increase daily vegetable and plant matter intake is important for many health reasons but it’s also important to recognise that by removing a food group, extra nutrient support may be required. Here are some following key points to support those following a vegetarian or vegan diet:

1. Vegetarian protein sources include lentils, pulses and brown rice – protein sources are often incomplete (except for quinoa) so a mix is required to provide the full complement of amino acids.
2. Cheese should not be relied on as the major dietary protein source. Cheese is high in fat and salt and protein can be found in other vegetarian sources such as pulses and beans.
3. Haem iron (meat source of iron) is better absorbed that non-haem form of iron found in plants.
4. Plant digestive enzyme supplement may be required to support break down of high levels of plant material (e.g. cellulase) and phytic acid (an anti-nutrient).
5. Zinc is required for immune health and production of stomach acid (among other health requirements) and is found in high levels in meat – highest vegan food sources of zinc include pumpkinseeds and nuts; daily supplement of this mineral may be recommended.
6. Vitamin B12 is found in dairy and meat and is an essential vitamin for supporting energy production. Long-term deficiencies (either from inadequate dietary intake or reduced absorption such as from pernicious anaemia) require correction with the bioactive methylcobalamin form of Vitamin B12 supplement (we will look at supplement nutrient forms later in Part 2).
7. Essential fatty acids (EFAs) are only consumed through the diet (our body cannot synthesise them), mainly from oily fish, as well as eggs. Vegan sources of essential fatty acids include flaxseeds (ground seeds and the oil) but this source delivers EFAs in a form that the body needs to convert to the bioactive EPA and DHA forms (found in oily fish). Supplements may be required to provide necessary levels for health including hormone production and balance and cell membrane structure, especially in the brain, though for those wishing to avoid all animal and fish based food supplements, flaxseed oil can be taken daily alongside nutrients such as magnesium, vitamin B6 and zinc, that helps the conversion of patron EFAs found in seeds to EPA and DHA.

Specific nutrients and supplements discussed in this section will be discussed in the food supplement module. Below is a summary table of the advantages and disadvantages of vegetarian and vegan diets.