Vegetarians and vegans must focus on several essential nutrients

If you are vegetarian or vegan you need keen insight in order to know how to get enough protein, vitamins, minerals, fatty acids, and certain amino acids. Lack of essential nutrients can cause anemia and fatigue but may also increase your risk of serious diseases.

Our diet must first of all contribute with energy-providing substances such as carbohydrate, fat, and protein. Vegetarians and vegans should focus on getting enough protein, as we need it for building muscles and for producing hormones, neurotransmitters, antibodies etc. The question is, how much protein do we actually need?

Protein requirement

The daily need for protein depends on gender, muscle mass, metabolism, and the degree of physical activity. The official recommendation for protein is around 1 gram for every kilogram of body weight. People who want to lose weight, pregnant women, and elite sportspeople have a higher protein requirement. Getting too little protein may cause problems like low blood sugar, fatigue, sleep disorders, overweight, impaired immunity, muscle weakness, and problems with skin, hair, and nails. Too much protein, on the other hand, can lead to acidosis, and certain protein-rich diets may result in increased urination and may also cause fat cells to absorb more fat.

The amino acid tryptophan

Protein consists of different amino acids with different functions in the body. For that reason, it is important to consume protein from different sources and to distribute the protein evenly among the main meals of the day. In contrast to meat and dairy products, plant food is generally low in the amino acid tryptophan, which is involved in the production of serotonin and melatonin, both of which are important for our nervous system and 24-hour rhythm (circadian rhythm). Nonetheless, bananas, sunflower seeds, soy beans, and peanuts contain a lot of tryptophan.

Vitamins and minerals

Vitamins and minerals help cells produce energy by means of numerous enzymatic processes. In addition, minerals support the formation of bones, skin, hair, and nails. Vegetarians and vegans should make sure to get enough vitamin D and vitamin B12, iron, selenium, and zinc plus essential fatty acids like omega-3.

It is also very important that the different nutrients can be absorbed and utilized.

Vitamin D

Good sources of vitamin D are cod liver, cod roe, oily fish, eggs, and high-fat dairy products, while sources such as avocado and olive oil contain vitamin D in comparatively smaller quantities. Because the summer sun is our most important source of vitamin D, it is virtually impossible for people in the northern hemisphere to get enough vitamin D during the winter period where the sun is too low in the sky to enable our skin to synthesize the vitamin. Lack of vitamin D increases the risk of infections, inflammation, osteoporosis, cancer, and numerous other health problems, simply because all our cells depend that much on this vital nutrient. We can only cover our need for vitamin D in the summertime, provided we expose ourselves to sufficient amounts of sunshine. In the winter period it is advisable to take a high-dosed vitamin D supplement.

Vitamin B12

Vitamin B12 is important for cellular energy metabolism, the formation of red blood cells, the immune system, nerve impulses, and our mental balance. The vitamin is found in meat, fish, eggs, and dairy products, which means that vegetarians and vegans in particular are at risk of becoming deficient. The uptake of vitamin B12 also requires a sufficient amount of gastric juice. Deficiency symptoms include anemia, fatigue, palpitations, nerve inflammation, impaired memory, dementia, and muscle weakness. Pernicious anemia is caused by autoimmune reactions.

Iron

Iron is part of the red blood cells and the brain enzymes that are important for our energy turnover, vitality, immune defense, growth, learning ability, plus skin, hair, and nails. Iron is found in liver, meat, eggs, pumpkin seeds, other seeds, beans, nettles, spinach, red beet, whole-grain, apricot and other fruits, and green vegetables. Iron from animal sources (hem-iron) is absorbed more readily the iron from vegetable sources (non-heme iron). On the other hand, many vegetable sources of iron also contain vitamin C, which supports the body's iron uptake. Weak gastric juice inhibits the iron uptake. Iron deficiency typically causes paleness due to the lack of blood. Other symptoms include fatigue, vertigo, palpitations, impaired immunity, changes of skin, hair, and nails, reduced growth, and learning disorders among children. Women of childbearing age are particularly susceptible to iron deficiency because of the blood they lose when they have their menstrual periods.

Selenium

Selenium supports around 30 different selenium-dependent proteins (selenoproteins) that are also powerful antioxidants. Selenium is especially important for the immune system (particularly against virus), the metabolism, cardiovascular system, sperm cell production, skin, hair, and nails, cancer prevention and protection against heavy metals.
Some of the best selenium sources are Brazil nuts, fish, shellfish, and seaweed plus organ meat, meat, and eggs. Smaller amounts of selenium are also found in other types of nuts, seeds, whole-grain, garlic, shitake mushrooms, broccoli, and various types of fruit and vegetables. The selenium content in crops varies, depending on the soil in which they have been cultivated. Because European agricultural soil is generally low in selenium, it is rather difficult for vegetarians and vegans to cover their need for this important nutrient. Lack of selenium increases the risk of cardiovascular disease and cancer. Also, too little selenium may result in metabolic disorders, infection, inflammation, and cataracts.

NOTE: The uptake of vitamin B12, iron and calcium requires sufficient gastric juice

Zinc

Zinc is an antioxidant that is necessary for around 300 different enzymatic processes, which control our growth, reproduction, metabolism, nervous system, immune system, skin, hair and nails, wound healing, sense of taste and many other functions. Good sources of zinc include oysters, liver, meat, shellfish, dairy products, nuts, seeds, kernels, and beans. Animal sources of zinc are easier for the body to absorb.

Lack of zinc may result in lethargy, skin and hair problems, impaired wound healing, reduced appetite, impaired sense of taste, pregnancy complications, weight loss, mental disturbances, and other serious health problems.

Omega-3

The omega-3 fatty acids are important for the construction of cell membranes, brain function, nervous system, cardiovascular system, blood pressure, skin and mucosa, immune system, and for some hormone-like compounds called prostaglandins that control inflammation and many other processes in the human body. The omega-3 fatty acids are found in different forms. Linseed oil, walnuts, and rapeseed oil contain the form of omega-3 called ALA (alpha-linoleic acid). Helped by different enzymes, ALA gets converted into EPA (eicosapentaenoic acid) and then into DHA (docosahexaenoic acid) before it finally gets converted into the before mentioned prostaglandins.

Because of lack of certain enzymes, the conversion from ALA to EPA and DHA is often limited, which means that the body lacks the important prostaglandins. For that reason, some people benefit more from getting EPA and DHA directly from the diet (oily fish and shellfish) or from supplements (fish oil, krill oil, or supplements based on sea algae.)

References

Nordiske Næringsstofanbefalinger

http://ajcn.nutrition.org/content/78/1/3.full

http://www.ncbi.nlm.nih.gov/pubmed/19499625

http://ajcn.nutrition.org/content/78/3/633S.full

http://frida.fooddata.dk/AlpList.php

https://da.wikipedia.org/wiki/Tryptophan

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