Is a Plant-Based Diet The Key to Human Health?

Should we be reducing or eliminating animal products from our diets?

In my experience, whenever someone I know has made the decision to follow a vegan or vegetarian diet they have been bombarded with all sorts of questions and concerns from others: Where will you get your protein? What about calcium? Aren’t all vegans weak, pale and deficient?! After recently watching the pro vegan documentary films Food choices and Carnage: swallowing the past, I felt it was time to start writing some blogs on this topic!

Nutrients in animal foods

  • Meat, fish, dairy and eggs are all excellent sources of high quality protein and contain all 9 essential amino acids. Protein is essential for many processes in the body such as hormone and enzyme synthesis, and the growth and repair of tissues.
  • Meat is a excellent source of  iron, zinc and B vitamins.
  • Dairy products are rich in calcium, and contain moderate amounts of vitamin D, iodine, B1 , B2 and B12. Natural yoghurt contains bacteria such as lactobacillus acidophilus and bifidobacterium which are beneficial for digestive health.
  • Eggs are a good source of vitamin A, B2, B3, B5, B6, B12, D, E, K, folic acid, choline, lutein, biotin, phosphorus, selenium and zinc.
  • Fish and seafood contain iodine and oily fish is an excellent source of essential omega 3 fatty acids, which must be obtained from the diet as our bodies cannot synthesise them.
  • The saturated fat present in meat, fish, dairy and eggs was once thought to contribute to high cholesterol and heart disease, however numerous recent studies have shown this is not the case.

If animal products are so nutritious, why reduce or eliminate them?

Animal welfare aside, the arguments in favour of consuming a plant based diet over one including meat are significant. Numerous studies suggests there are negative effects of consuming animal products, especially in excess. Dairy products in particular have come under a lot of scrutiny as humans are the only species  who consume the milk of another animal!

  • When you consume large quantities of animal products this can result in a diet very high in protein, which can put strain on the liver and kidneys in the long term, especially in those who already suffer from a liver or kidney disease.
  • Excessive animal products in a person’s diet often displace fruits, vegetables and other high fibre foods, which are important for reducing the risk of many diseases.
  • Intensively farmed animals are often given cheap poor quality feed, which negatively changes the nutritional composition of the meat, fish dairy and eggs that we eat.
  • Wild fish contain mercury and polychlorinated biphenyls (PCBs) which can have negative effects on the nervous system and contribute to conditions such as cancer and infertility (1). The larger the fish, the higher the concentration of these toxins.
  • Dairy products account for 60-70% of dietary oestrogen consumed by humans. Evidence to date suggests oestrogen and the other steroid hormones naturally present in milk have the potential to cause negative health effects, even in relatively low doses (2). Whilst more research is needed, because cancers such as breast and prostate are hormone dependent, it seems sensible for those with a strong family history of these cancers to consume dairy with caution.
  •  Insulin-like growth factor (IGF-1) is another naturally occurring hormone in dairy produce. Its function is to stimulate cell growth. The more dairy you consume, the higher your blood level of IGF-1. This is good news for growing babies who consume it in breast milk but IGF-1 has also been shown to directly stimulate the growth of cancer cells. High blood levels of IGF-1 are associated with an increased risk of cancer, particularly of the breast (3), prostate, colon and lung.
  • The increased incidence of autoimmune diseases such as type 1 diabetes and multiple sclerosis have been strongly correlated to dairy intake.

Other factors to consider:

  • Intensively farming animals for their products is extremely damaging to the environment because the methane produced by livestock significantly contributes to climate change (4).
  • In addition, the constant and increasing demand for animal protein worldwide has led to the overuse of antibiotics in livestock, therefore contributing to antibiotic resistance. Experts have found parallels between antibiotic resistance in animals and related antibiotic resistance in humans (5).

In conclusion, our planet and the majority of people who live on it would benefit from reducing their intake of animal products. The majority of nutrients present in these foods can be obtained from plant sources. I would recommend consuming small amounts of  organic meat, dairy and eggs, and to choose small wild fish such as sardines, mackerel and herring. It is not necessary for every meal to contain animal products. Try having 2-3 vegan days per week including plenty of vegetables, whole grains, nuts, beans and pulses.

You might also like: Can a Vegan Diet Meet All Your Nutritional Requirements?


Author: Sarah Turner is a BANT registered nutritional therapist and blogger, recipe developer and researcher for Louise Digby Nutrition. Sarah is studying physiotherapy and plan on providing a fusion of nutrition and manual therapy upon graduation!














  1. International agency for research on cancer (IARC).2016. Polychlorinated biphenyls and polybrominated biphenyl.
  2. Malekinejad, H., Rezabakhsh, A. 2015. Hormones in Dairy Foods and Their Impact on Public Health – A Narrative Review Article.
  3. Wu MH1, Chou YC, Chou WY, Hsu GC, Chu CH, Yu CP, Yu JC, Sun CA.2010. Relationships between critical period of estrogen exposure and circulating levels of insulin-like growth factor-I (IGF-I) in breast cancer: evidence from a case-control study. Int J Cancer. 126 (2) :508-514
  4. Ripple, W.J., Smith, P., Haberl, H., Montzka, S.A., McAlpine, C., Boucher, D.H. 2014. Ruminants, climate change and climate policy. Nature Climate Change, 4 (2-5).
  5. Gelband, H., Miller-Petrie, M., Pant, S., Gandra, S., Levinson, J., Barter, D., White, A., Laxminarayan, R. 2015. The State of the World’s Antibiotics.