Vegan diets are highly regarded for their nutritional benefits and protection against an array of chronic diseases including cardiovascular disease, type 2 diabetes and cancers(1,2,3). However, when consuming these diets, which are generally more restrictive in nature, it is essential that diets are well planned with at-risk nutrients taken into consideration. The most common at risk nutrients on a vegan diet include; essential fatty acids – omega 3s, zinc, calcium, vitamin D, vitamin B12 and iron. Nevertheless, a well-planned vegan diet is suitable for all stages of life and can meet the nutrient requirements to achieve optimal health(4).
What are essential fatty acids?
All fats contain something called fatty acids, these can either be saturated, monounsaturated and polyunsaturated. They all slightly differ in chemical structure, thus providing different health benefits(5). Poly and monounsaturated fatty acids are more beneficial to health as they help to decrease risk of heart disease, lower blood pressure, lower blood triglycerides and lower blood cholesterol(5), whilst saturated and trans-fatty acids are not beneficial to health as they cause an increase in total blood cholesterol, increase the risk for heart disease and cause fatty, sticky deposits to build up in the arteries which causes them to narrow and increase risk of blockages(6).Most plant based foods contain poly or monounsaturated fats, with the exception being the highly saturated coconut and palm oils(6). On the other hand, saturated fat is the predominant fat found in a lot of discretionary items, processed foods, meat and dairy products(6).
Why do we need fats
Saturated and monounsaturated fats can be synthesised (created) by the body, and therefore are not “essential” – do not need to come from our diet (1,2,7). However, two polyunsaturated fatty acids called “linoleic acid” (omega 6 fatty acid)and ‘alpha-linolenic acid” (omega 3 fatty acid) can not be made by our body and MUST be provided by our diet(1,2). These acids are called “essential” and after digestion get converted to long chain fatty acids; , linoleic acid is converted to arachidonic acid and ALA is converted to eicosapentaenoic acid (EPA) and docosahexaneoic acid (DHA)(1,3).
So what does our body use these polyunsaturated fats for?
These polyunsaturated fatty acids are important in helping the body do a whole range of functions including:
maintaining the membrane of all cells(1,3)
brain and eye development(1,3)
making prostaglandins – these regulate body processes including inflammaion and blood clotting (2,3)
protect against heart disease(1,2,3)
allow the absorption of fat soluble vitamins A, D, E and K from food (1,3)
regulating body cholesterol metabolism(1,3)
QUESTION: “I heard we need EPA and DHA in our diets and that we can only get it from fish?”
Fish are a natural source of Eiocosapentaenoic acid (EPA) and Docosahexaneoic acid (DHA) and by eating these foods we directly are able to consume these fatty acids from our diet2,7. However, Alpha-linolenic acid (omega 3 acid), which is found in various plant based foods can also be converted by the body into DHA, EPA (2,3,7). There are various factors that affect the rate that this conversion occurs, however it has been found that a high intake of a linoleic acid (omega 6 acid), does suppress the body’s ability to carry out this conversion to DHA(1,2,3). However, it is not only in the vegan population but the greater population in general that are consuming higher amounts of omega 6s, more than the recommended omega 6 to omega 3 ratio.
Therefore everybody can achieve a better ratio between omega 6 and omega 3 fatty acids to optimise the conversion of Alpha-Linolenic Acid to EPA and especially DHA (1,2).
Reducing the number of sunflower, safflower and corn oils that are consumed, and swapping this instead for Alpha-linolenic acid containing oils including canola, soy bean and walnut oils(1,2,3)
Eating omega 3 fatty acids from foods including flaxseeds and flaxseed oil, hempseed products, walnuts(1,2,3)
Avoiding foods high in trans-fatty acids and saturated fats.(1,2,3)
So what are the ‘healthy’ fats that I should be eating?
Linoleic Acid (Omega 6 family) (2,3)
oils including: safflower, sunflower, corn, soya, evening primrose, pumpkin, wheatgerm
Alpha-Linoleic Acid (Omega 3s)(1,2,3,7)
Green leafy Vegetables
Oils from: linseed, rapeseed (canola), hempseed
How much omega 3s should I be eating on a vegan diet?
To avoid deficiency, it is recommended for individuals who are not using a DHA supplement that adult males should include a minimum of 2.6g of ALA and females 1.6g of ALA every day(1).
Dietitians Association of Australia. (2014). Omega-3 Fatty Acids and Vegetarian Diets. Retrieved from http://www.pennutrition.com.ezp01.library.qut.edu.au/docviewer.aspx?id=11713
The Vegan Society. (N.D). Omega 3 and Omega 6 Essential Fatty Acids. Retrieved from http://www.vegansociety.com/sites/default/files/Omega%203%20and%20Omega%206%20Essential%20Fatty%20Acids.pdf
Mangels, R., Messina, V., & Messina, M. (2011). The dietitian’s guide to vegetarian diets: Issues and applications(3rd ed.). Sudbury, MA: Jones & Bartlett Learning
Dietitian Association of Australia. (2016). Vegan Diets. Retrieved from http://daa.asn.au/for-the-public/smart-eating-for-you/nutrition-a-z/vegan-diets/
Dietitian Association of Australia. (2016). Unsaturated Fats. Retrieved from http://daa.asn.au/for-the-public/smart-eating-for-you/nutrition-a-z/unsaturated-fats/1
Dietitians Association of Australia. (2016). Saturated Fat. Retrieved from http://daa.asn.au/?page_id=865
Dietitians of Canada. (2013). Food Sources of Omega-3 Fats. Retrieved from http://www.dietitians.ca/Downloads/Factsheets/Food-Sources-of-Omega-3-Fats.aspx