Vegetarian = Healthy?

Many people thought that, by simply adopting a vegetarian diet, they are automatically eating healthily. Is this true?

Vegetarian Curry

Undoubtedly, scientific evidence does show that vegetarians clearly experience less cardiovascular diseases (CVD) than non-vegetarians. Other potential benefits of vegetarian diet may include lower body mass index (BMI), lower LDL cholesterols, as well as lower incidents of treated hypertension and diabetes [1]. Therefore, public health agencies also routinely stressed on the need to consume more fruit and vegetables as well as less saturated animal fat, to reduce the risk of chronic diseases [2].

However, lower risk does not been no risk. There are many lifelong vegetarians who also have CVD, diabetes, hypertension, high cholesterol, and cancer. Many factors can contribute to the cause of chronic diseases and improperly applied or unbalanced vegetarian diet can significantly reduce the potential benefits of vegetarian diet.

Vegetarian - healthy?

Here are a number of important nutritional considerations for all vegetarians to take note of.

Too much refined carbohydrate

With the absence of animal proteins and fats from the diet, naturally, a much higher percentage of energy intakes for vegetarians come from carbohydrates. This is especially true for a typical Chinese/East Asian vegetarian diet, which consists mainly of rices/noodles, vegetables, and tofu. Traditionally, such a diet is very low in fat and very high in carbohydrates (e.g. < 20% energy from fat and > 70% from carbohydrates); this diet is known to be cardioprotective with most of the carbohydrates come from minimally processed grains, legumes, and vegetables [4] [5].

Vegetarian noodles

Unfortunately, this is no longer true today. Nowadays, vegetarian foods tend to make up from a lot of refined carbohydrates such as white rice, highly processed noodles, white breads, sugar laden sauces and desserts. These are foods with high glycaemic index (GI) which can be easily converted into blood glucose in the body. Excessive intake of high GI foods leads to overweight and obesity.  Long term intake of high carbohydrate foods with high GI also increases insulin resistance in the body that can lead to type II diabetes [6]. A prospective cohort study with 53,644 subjects over a 12 year period also found that the risk for myocardial infarction (i.e. heart attack) actually increase for subjects that substituted saturated fats with high GI carbohydrates [7].

Hence, a vegetarian diet that consists of high-GI carbohydrates is actually worse than an animal-based diet high in saturated fat!

High omega-6 to omega-3 polyunsaturated fat ratio

There are different types of fats in foods and the body. They can be classified into saturated, monounsaturated and polyunsaturated fatty acids (PUFAs).  PUFAs can be further classified into the omega-3 (ω-3) and the omega-6 (ω-6) families. ω-3 families of PUFAs plays an important anti-inflammatory role in the body, whereas ω-6 families of PUFAs are pro-inflammatory mediators. It has been suggested that an ideal ω-6/ω-3 ratio for health in the human body should be between 1:1 to 2:1 [8]. However, modern-day’s diet is drastically high in ω-6 PUFAs and low in ω-3 PUFAs, even to the ratio of 15:1. Such imbalance has been linked to the increases in chronic inflammatory diseases such as nonalcoholic fatty liver disease, CVD, obesity, inflammatory bowel disease, rheumatoid arthritis, and Alzheimer’s disease [9]. Current evidence has also indicated that PUFAs play a role in cancer risk and progression with high ratio of ω-6 PUFAs increasing the risk of cancer [10].

Chia seeds

Chia seeds – an excellent source of omega 3 fatty acids (ALA) for vegetarians

Vegetarian diet can easily become high in ω-6 PUFAs and low in ω-3 PUFAs. Vegetable oils in the market such as safflower, sunflower oil, corn oil, shortening, and margarine are all rich sources of ω-6 PUFAs [11]. These oils are also used extensively in commercial cooking due to their low cost. Furthermore, by eliminating fish and seafood from the diet, vegetarians are not taking two important types of ω-3 PUFAs: docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Although DHA and EPA are also available from microalgae, it is not a common food source for most people. DHA and EPA can also be converted from α-linolenic acid (ALA) of plant sources (e.g. Chia seed, walnut, hemp seed), but the conversion process is slow and age-dependent [12]. They are also not part of most vegetarian diet.

As such, without paying attention to the balance of ω-6 to ω-3 PUFAs in the diet, the risk of chronic inflammatory conditions and cancer among vegetarians are no better than meat eaters.

Imbalance in micronutrients

Vegetarian diet, if properly planned, is nutritionally adequate for both adults and children. However, if a vegetarian is not conscious of his/her dietary choices, then there is a risk of developing deficiency in certain micronutrients, including vitamin B12, vitamin D, calcium, iron, and zinc [13].

Vitamin B12

Among these nutrients, vitamin B12 deficiency is especially common among those who observe strict vegan diet. Vitamin B12 is produced by bacteria. It can be produced in the human intestine, but insufficient for human needs. Common sources of vitamin B12 include meats, fish, seafood, cheese, and eggs. Therefore, lacto-ovo vegetarian who consume sufficient cheese and eggs can meet intake requirements of vitamin B12. However, for vegan, natural food sources for vitamin B12 are very limited. Known sources include fermented beans, yeast extract, certain wild mushrooms, and dried purple laver (nori) [14].

Sliced tempeh

Fermented soybean like tempeh may contain some vitamin B12, but the level may not be consistent.

Levels of vitamin B12 in these food sources also vary considerably. Therefore, it is prudent for vegan to consider supplementing with vitamin B12 from time to time. Deficiency in vitamin B12 can affect the nervous system and presented as a variety of symptoms, which include fatigue, lack of energy, loss of concentration, and nerve problems [15].

Vitamin D & Calcium

The level of vitamin D in blood, in the form of plasma 25(OH)D has been consistently found to be lower in vegetarians than non-vegetarians [16]. Vitamin D can be synthesized by the action of sunlight on skin. Common food sources of vitamin D are fish liver oils, butter, egg yolk, milk, sprouted beans, and sun-dried mushrooms [17].

Sungazing

Get more vitamin D by exposing your skin to morning sunlight. Vitamin D is important for calcium absorption and bone health.

For vegetarians who are staying indoors most of the time and are selective in their food choices, the risk of developing vitamin D is high. Vitamin D plays an important role in the absorption of calcium in the body. Insufficient calcium absorption can adversely affect the bone health. Therefore, vegetarians, and particularly vegans, may be at greater risk of lower bone mass density (osteoporosis) and fracture if not taking sufficient level of vitamin D [18].

Iron

Iron is an essential nutrient for haemoglobin in red blood cells. It is vital for the health and proper functioning of the body. Deficiency in iron reduces the capacity of the blood to carry oxygen to the cells, resulting in weakness, fatigue, reduced immunity, shortness of breath, sensitivity to cold, and heart palpitations.

Broccoli is a great source of iron for vegetarians

Broccoli is a great source of iron for vegetarians

There are two types of iron in food: haem and non-haem. Haem iron which comes from animal foods is easily absorbed by the body. Plant-based foods contain only non-haem iron which is harder to absorb by the body. For this reason, it is commonly thought that vegetarians are more prone to iron deficiency. The absorption of non-haem iron can be enhanced by the presence of vitamin C [19]. Therefore, it is important for vegetarians to eat both iron-rich foods (including whole grain cereals and breads, dried beans and legumes, dark green leafy vegetables, dried fruits, nuts, and seeds), together with vitamin C rich foods such as citrus fruits, papaya, and guava.

Zinc

By HealthAliciousNess from www.healthaliciousness.com

Eat a handful of pumpkin seeds everyday to ensure adequate zinc intake.

Zinc is another trace mineral that is important for the body functions. It is a co-factor for more than 300 enzymes and proteins in the body that are involved in defence of oxidative stress [17]. Although there are many plant-based sources of zinc such as capsicum, sunflower seeds, pumpkin seeds, and whole grains, the bioavailability of zinc from these sources can be poor. It is due to the high level of phytate in plant-based foods. Phytate can inhibit the absorption of not only zinc, but also iron and calcium. Population studies have consistently shown that vegetarians tend to have a lower zinc intake and state [20].  Zinc deficiency can exhibit various symptoms, including hair loss, diarrhoea, impotence, eye and skin conditions, etc. [17]. Hence, vegetarians need to take more zinc-rich foods to ensure better absorption.

Dietary Recommendations

Here are some recommendations for a healthy, well-balanced vegetarian diet that can help to reduce the risk of chronic diseases and allow the body to achieve its peak performance:

  1. Eat a variety of natural plant-based foods, including whole grains, fruits, vegetables, legumes, nuts and seeds. Do not exclude any major food groups.
  2. Reduce the intake of high GI foods, especially sugar and refined carbohydrates such as white rice, white bread, soda, confectionaries and desserts.
  3. Avoid highly processed foods such as canned foods and drinks, mocked vegetarian products, instant noodles, etc.
  4. Avoid deep-fry foods, especially when eating out.
  5. Use the right kind of oil for cooking. Avoid high omega-6 oils. Use olive oil or pure virgin coconut oil.
  6. Include rich sources of plant-based omega-3 foods such as Chia seeds and flax seeds.
  7. Include healthy fermented foods such as miso, fermented tofu, tempeh, kefir, etc.
  8. Make sure to include seaweed products in your diet, they are rich in vitamins and minerals.
  9. Consider taking vitamin B12 supplements periodically.
  10. Exercise outdoors regularly for sunlight exposure.
Eat plant-based whole foods that are minimally processed.

For good health, eat plant-based whole foods that are minimally processed.

Conclusion

In summary, vegetarian diet can help to improve health and wellbeing. However, improperly applied and unbalanced vegetarian diet can be detrimental to health. For vegetarians, the important nutritional considerations are to avoid high GI high carbohydrate diet, balance omega-6 fatty acid with sufficient omega-3 fatty acid intake, as well as ensure sufficient intake of vitamin B12, D, calcium, zinc and iron from a variety of foods and supplementary sources. A diet high in a variety of plant-based whole foods with minimal processed foods should be ideal. Supplementing diet with vitamin B12 is also a prudent practice.

References

  1. Fraser, G. E. (2009). Vegetarian diets: what do we know of their effects on common chronic diseases? The American Journal of Clinical Nutrition, 89(5), 1607S-1612S. doi: 10.3945/ ajcn.2009.26736K
  2. Health Promotion Board. (2015, October 29). Food-based Dietary Guidelines for Adults. Retrieved February 26, 2016, from http://www.hpb.gov.sg/HOPPortal/health-article/2758
  3. Katz, D.L. & Meller, S. (2014). Can We Say What Diet Is Best for Health? Annual Review of Public Health, 35, 83-103. Doi: 10.1146/annurev-publhealth-032013-182351
  4. Hu, F. B. (2010). Are refined carbohydrates worse than saturated fat? The American Journal of Clinical Nutrition, 91(6), 1541–1542. http://doi.org/10.3945/ajcn.2010.29622
  5. Campbell, T. C. & Campbell, T. M. II (2006). The China Study: the most comprehensive study of nutrition ever conducted and the startling implications for diet, weight loss, and long-term health. BenBella Books: Dallas, TX, USA.
  6. Willett, W., Manson, J., & Liu, S. (2002). Glycemic index, glycemic load, and risk of type 2 diabetes. The American Journal of Clinical Nutrition. 76(suppl):274S–80S.
  7. Jakobsen, M.U., Dethlefsen, C., Joensen, A.M., Stegger, J., Tjønneland, A., Schmidt, E.B., & Overvad, K. (2010). Intake of carbohydrates compared with intake of saturated fatty acids and risk of myocardial infarction: importance of the glycemic index. The American Journal of Clinical Nutrition, 91(6), 1764-1768. doi: 10.3945/​ajcn.2009.29099.
  8. Simopoulos, A. P. (2011). Evolutionary aspects of diet: The omega-6/omega-3 ratio and the brain. Molecular Neurobiology, 44(2), 203-215. doi: 10.1007/s12035-010-8162-0.
  9. Patterson, E., Wall, R., Fitzgerald, G. F., Ross, R. P., & Stanton, C. (2012). Health Implications of High Dietary Omega-6 Polyunsaturated Fatty Acids. Journal of Nutrition and Metabolism, 2012, 539426. doi:10.1155/2012/539426
  10. Whitbread, D. & House, P. (n.d.). Top 10 foods highest in omega 6 fatty acids. Retrieved February 29, 2016, from https://www.healthaliciousness.com/articles/high-omega-6-foods.php
  11. Azrad, M., Turgeon, C., & Demark-Wahnefried, W. (2013). Current Evidence Linking Polyunsaturated Fatty Acids with Cancer Risk and Progression. Frontiers in Oncology, 3, 224. doi:10.3389/fonc.2013.00224
  12. Saunders, A. V., Davis, B. C., & Garg, M. L. (2012). Omega-3 polyunsaturated fatty acids and vegetarian diets. The Medical Journal of Australia, 1(Suppl 2), 22-26. doi:10.5694/mjao11.11507
  13. Craig, W. J. (2010). Nutrition concerns and health effects of vegetarian diets. Nutrition in Clinical Practice, 25(6), 613-620. doi: 10.1177/0884533610385707
  14. Watanabe, F., Yabuta, Y., Bito, T., & Teng, F. (2014). Vitamin B12-containing plant food sources for vegetarians. Nutrients, 6(5), 1861–1873. doi:10.3390/nu6051861
  15. com (n.d.). Vitamin B12 deficiency. Retrieved 1 Mar, 2016 from http://www.webmd.com/food-recipes/guide/vitamin-b12-deficiency-symptoms-causes?page=2
  16. Crowe, F. L., Steur, M., Allen, N. E., Appleby, P. N., Travis, R. C., & Key, T. J. (2010). Plasma concentrations of 25-hydroxyvitamin D in meat eaters, fish eaters, vegetarians and vegans: results from the EPIC–Oxford study. Public Health Nutrition, 14(2), 340-346. doi:10.1017/S1368980010002454
  17. Osiecki, H. (2014). The Nutrient Bible, 9th BioConcept: Eagle Farm, QLD.
  18. Tucker, K. L. (2014). Vegetarian diets and bone status. American Journal of Clinical Nutrition, 100(Suppl 1), 329S-335S. doi: 10.3945/​ajcn.113.071621
  19. Saunders, A. V., Craig, W. J., Baines, S. K., & Posen, J. S. (2012). MJA Open, 1 (Suppl 1), 11-16. doi: 10.5694/mjao11.11494
  20. Foster, M., Chu, A., Petocz, P., & Samman, S. (2013). Effect of vegetarian diets on zinc status: a systematic review and meta-analysis of studies in humans. Journal of the Science of Food and Agriculture, 93(1), 2362–2371. doi: 10.1002/jsfa.6179.
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