Vegetarians and vegans may exhibit wide diversity in their dietary practices, but they are linked by what they omit from their diet. When a vegetarian/vegan diet is well-planned, diverse in choice and includes fortified foods, it can be nutritionally adequate, offering a wide variety of health benefits for both adults and children.
Knowing which nutrients could be missing from the diet can help the health conscious vegetarian/vegan to plan meals ensuring all aspects of good nutrition are met. As such, we have listed the most common nutrients whose absence may be of concern.
Omega-3 fatty acids
The long-chain omega-3 fatty acids, EPA and DHA are important for cardiovascular health, improving immune function and counteracting inflammation, as well as for infant visual function and neurodevelopment. Compared with non-vegetarians, vegetarians (and particularly vegans) tend to have lower blood levels of EPA and DHA as these are predominantly found in marine foods. Non-fish eaters must derive these long-chain fats from the plant-derived omega-3 ALA.
Physical signs of fatty acid deficiency include rough or dry skin and hair, dandruff, and soft or brittle nails, low mood and forgetfulness. Long-term omega-3 deficiency is linked to a number of cardiovascular, inflammatory and autoimmune diseases, as well as conditions such as depression and chronic fatigue syndrome that respond well when EPA levels are increased. Whilst there are algae sources of DHA, no vegetarian source of EPA is currently available. ALA, the precursor to EPA and predominantly found in seeds, nuts and oils such as flaxseed oil, doesn’t convert well to EPA and DHA. Echium seed oil, on the other hand, is a new and unique source of omega-3 that has ‘fish-oil like’ qualities because of its high content of the omega-3 fatty acid SDA and is considered to be an ideal solution for vegetarians and vegans to achieve optimal omega-3 levels.
Zinc is required to support numerous functions within the body, including supporting the body’s immune system. Although overt zinc deficiency is not common in vegetarians, their zinc intakes may be marginal or fall below recommendations. Vegetarians and vegans consume foods that are high in products called phytates, compounds that can have a significant effect on zinc absorption. As such, vegetarians consuming diets rich in unrefined grains, nuts, and legumes, may have zinc requirements that are higher than non-vegetarians. Consuming fortified cereals can help meet requirements, and certain food preparation techniques, such as soaking and sprouting beans, grains, and seeds can increase zinc bioavailability.
Vitamin B12 or cobalamin is needed for building proteins in the body, the formation of red blood cells, and for the normal function of the nervous system. A slight deficiency of vitamin B-12 can lead to anaemia, fatigue, mania, and depression, while a long-term deficiency can potentially impact on the normal function of the nervous system. Whilst found in high amounts in cheese, eggs, and milk, vegans must obtain this important vitamin through fortified foods, such as fortified soy and rice beverages, breakfast cereals and meat substitutes, with marmite being a well recognised source.
Iron is probably best known for its role in forming haemoglobin, needed for transporting oxygen around the body in red blood cells. Vegetarians often have an iron intake that is similar to or slightly better than that of non-vegetarians, so the issue of iron adequacy is really one of iron bioavailability. Iron from plant sources or ‘non-heme’ iron is less well absorbed than iron derived from animal sources. People should avoid drinking beverages, such as tea, coffee, herb teas, or cocoa, with meals as compounds like phytates, and the polyphenolics present in these drinks, can seriously reduce the bioavailability of iron. On the other hand, swapping for drinks known to be a rich source of vitamin C such as orange juice will help increase iron absorption from plant foods.
Calcium is the most abundant mineral in the body, providing structure for bones and teeth, aiding in the control of muscle and nerve function and playing a role in blood clotting. Calcium intakes of lacto-vegetarians are similar to, or may be higher than, those of non-vegetarians, whereas intakes of vegans tend to be lower than both groups and may fall below recommended intakes. As such, vegans may require calcium-fortified foods such as fruit juices, soy and rice milk, and fortified breakfast cereals to meet their calcium needs. Calcium levels are regulated in part by vitamin D, which is present in spreads and fortified cereals. Vitamin D is also made in the skin through sun exposure, so getting out into the sunshine is another way of increasing levels.
Being aware of which nutrients are needed daily and which possibly less often, what not to eat with certain foods, and which foods should definitely be combined may require a little education but also ensures that the vegetarian or vegan diet not only offers colourful and tasty food but food that is sufficiently nutritious to meet all of the body’s requirements.