Nutrition and Digestion: Is Vegetarianism Appropriate?

Chris Kummer, Naturopath and Health Educator


Inadequate nutrition and diet are implicated in many modern diseases. Chris Kummer explains how the digestive system can inform dietary choices, including vegetarianism.


Dietary approaches to health and their proposed benefits are as copious as the issues of entertaining magazines. The confusion and loss of confidence in any particular dietary approach are preventing many from even considering a particular dietary style. Any diet containing adequate levels of protein, meat-based or vegetarian, is appropriate to deliver sufficient levels of amino acids to the body. Each person needs to find a diet that not only provides nutrient levels necessary for their lifestyle, but also is appropriate for their individual environment, life and work habits, climate and digestive ability.


Digestion and Disease

 A common denominator in all diets is the presence of the digestive system. Research evidence and physiological knowledge demonstrate clearly the variances in digestive function. Age, foods, environment, taste, ethnicity and state of the autonomic nervous system have considerable impact on digestive ability and function. Through this knowledge the saying “you are what you eat” has to be revised to “you are what you can absorb and utilize”.


  The incidence of constipation, allergies, ulcerative colitis, coeliac disease, Crohn’s disease, irritable bowel syndrome, reflux, leaky gut syndrome and diverticular disease and asthma, has prompted an increased awareness of the digestive system and food input. In light of the most common diseases of civilisation, general nutritional orientation and the selection of types of food deserve examination.

  The idea of the digestive system playing a central role for the majority of current diseases is shared today not only by the evidence based naturopathic medicine, but is also reflected in traditional Chinese and Indian (Ayurvedic) medicine traditions. The health implications of nutrition can be understood by considering the basic functions and limitations of the digestive system. Health is defined here not only as the absence of disease but overall well being. This includes good levels of energy, a healthy immune system and mental–emotional health.

  The digestive system extends from the mouth through the oesophagus into the stomach. Continuing through the small intestine with associated digestive substance producing organs, it connects to the large intestine, ending at the rectum and anus.

  Digestion is the breakdown process of food into nutrient particles that can be used for body functions and repair; a functioning digestive system is indispensable for energy, organ and tissue support, and it is also highly involved in the immune system.

  Most nutrients fall into one of two categories. They are either used for building and maintenance of the respective tissue, or for energy production.

  After food is broken down during digestion, it is rebuilt into the specific components of the body at a cellular level. For example eating meat does not directly supply protein for our system. Through digestive effort, meat protein is broken down into its component amino acids.

After absorption, the amino acids are transported via the bloodstream to the various tissues throughout the body, where they are synthesised into the proteins needed.


Acidity and Food

  Within the body, homoeostatic (balanced) environments ensure continuing health, for example maintaining body temperature at 37ºC.

  A particular acidity or alkalinity (pH level) is characteristic for most tissues (see table). Deviations from this level mean loss of function or, in extreme situations, death. Blood needs to be maintained at a pH of 7.36.

  A deviation of only 5% from this value, whether more acidic or more alkaline, results in heart failure and death.


pH Levels of Organs and Body Fluids Organ or fluid pH level

Saliva 6.5 to 7 (slightly acidic to neutral)

Blood 7.36 (slightly alkaline)

Stomach 1.5 to 3 (very acidic)

Pancreatic juice 8.8 (alkaline)

Bile 7 to 7.7 (slightly alkaline)

Small intestine 7 to 7.5 (slightly alkaline)

Large intestine 6.5 to 7.3 (slightly acidic to slightly alkaline)

Urine 6.5 to 7 (slightly acidic to neutral)


  During the digestive process, food moves from a slightly acidic to a neutral environment in the mouth to a highly acidic one in the stomach, before being buffered with bicarbonate ions in the small intestine.

  Low pH levels of the hydrochloric acid of the stomach are as much for digestive purposes as they are for the immune system. A healthy stomach will kill bacteria, moulds, viruses and other harmful organisms, before they can affect health. This illustrates the importance of good stomach acid levels for immunity.   Protein and mineral digestion is highly dependent on good acid levels of the stomach. For minerals to be absorbed across the intestinal membrane, they need to be present in ionic form. The action of hydrochloric acid cleaves the minerals off their compound structures.

  Once the churning of the stomach empties the content (chyme) in small amounts into the first part of the small intestine (duodenum), the acid concentration determines the amount of digestive enzymes and bicarbonate ions released from the pancreas. Inadequate stomach acidity results in low output from the pancreas, further reducing digestive efficiency.


Signs and symptoms of insufficient stomach acid production include:

• bloating, belching and fullness after eating

• acne and skin problems

• chronic fungal and bacterial infections

• enlarged blood vessels in cheeks and nose

• iron deficiency

• multiple food allergies

• weak, peeling, cracked fingernails

• undigested food in stools

• indigestion, constipation and diarrhoea.


  Along the small intestine, in the jejunum and ileum, the pancreatic and bile secretions alkalise the content, permitting a hospitable environment for bacteria. The large intestine has a generally neutral to slightly alkaline environment to accommodate large numbers of bacteria and organisms to thrive.

  Large intestinal action is bacterial fermentation, producing B-vitamins (including vitamin B12) and short chain fatty acids. These are necessary for healthy function and development of mucosal cells of the large intestine. A good balance of bacterial growth in the large intestine regulates the local micro-flora, immune response and lowers cholesterol.

  All foods have an effect on the pH levels in the body:

• Release of hydrochloric acid and the resulting digestive enzyme release of contributing digestive organs is generally proportional to the protein level of a meal. Thus digestion may be insufficient for low protein diets, with repercussions for pH balance.

• Hydrochloric acid is also needed to release bound minerals from foods into their ionic form for absorption. The type of mineral determines acidity or alkalinity in the tissues after absorption. Thus mineral content and balance of food, combined with the state of the digestive system, have a direct relationship to the tissue pH level.

  The alkaline elements are calcium, magnesium, sodium, potassium and iron, while the acidic elements include sulfur, phosphorus and chlorine. Concentrations of alkaline elements are highest in vegetables and fruit, while animal foods and other high protein foods are high in acidic elements. (Note that taste is not an indicator of acidity or alkalinity of a food for the tissues.)

  The post-digestive effect in body tissues of animal or high protein foods is acidic, necessitating the body to use alkaline minerals for buffering and neutralisation to maintain a homeostatic balance. Further foods creating an acidic environment in the body are most grains, sugar and alcohol. The process of refining foods often eliminates the alkaline forming minerals from the food, leaving an imbalanced product for the body to digest.


  Increased tissue acid is related to:

• obesity

• lowered immunity

• lack of energy

• cancer

• diabetes

• osteoarthritis

• osteoporosis

• blood clotting problems

• atherosclerosis.


  The principle of acid and alkaline balance of foods and tissues was expounded thoroughly by the macrobiotic diet approach and detailed in Herman Aihara’s book Acid and Alkaline. Many branches of the natural health profession have since adopted it.

  A collection of research articles observing the influence of metabolic acidity on bone health, ageing, kidney health, pain, tooth formation, growth and osteoporosis can be found online (see Further Reading).

  Research by Thomas Remer, published in the European Journal of Nutrition in 2001, looked at acid excretion of the body via the renal system, indicative for surplus acidity in the body. The conclusion was that equal amounts of either meat or soy protein produce similar levels of acid in the body.

  The study found that:

• dietary intakes must consider the specific bioavailability of individual nutrients • increased protein intake does not necessarily result in increased acid excretion, because additional alkali loads in an appropriately composed diet can compensate for the protein-related raised acid production.

  The balance of our food selection is important, no matter what kind of diet is followed.


Meat: to Eat or Not to Eat?

A medical parameter based study of people living on a variety of diets, ranging from meat based to vegan raw food, was conducted and reported on Australian television earlier in 2007 ( Measured by blood test were cholesterol levels, iron, zinc, protein and vitamin B12, all essential ingredients for long-term health.

  The results of the study showed adequate nutrient levels in the people eating balanced diets, meat included or vegetarian. Deficiencies or imbalances of nutrients showed in the people eating extreme diets – depleted levels of vitamin B12 in the vegan and strongly elevated cholesterol in the high meat eater. The blood lipid composition of the balanced vegetarian demonstrated cholesterol lowering properties.

  Animal protein provides all nine essential amino acids necessary for building new proteins in the body. Most choices of vegetarian protein do not provide the full range of amino acids. This indicates the necessity for anyone on diets excluding food types or food groups to be more aware of their selection. For example, being vegetarian and simply leaving out the meat from the dishes can lead to nutrient deficiencies.

  To the body it is irrelevant whether the range of essential amino acids is derived from one food source or many, so an appropriately balanced choice of acid and alkaline forming foods, based on mineral composition, needs to go hand in hand with combining protein sources for individuals not eating meat.

  Protein synthesis is fairly rapid in the body, so balanced protein intake needs to occur regularly in one or two successive meals. Unbalanced diets will see the unused amino acids converted into storage fat.

  Humans have always eaten meat-containing diets. Different to some vegetarian cultures in the world, Anglo-Saxons have a long history of consuming meat. Only over the past 200 years, especially in the last 50 years, have farming methods changed to a degree that renders meat eating less healthy.

  Meat contains far higher levels of fat and kilojoules than it has previously. Per weight, meat now contains on average seven times more fat and three times more kilojoules. Noteworthy is the change within the animal fat: structural fat (high in unsaturated fat) is now far outweighed by storage fat (high in saturated fats). Protein to fat ratio has been reversed, with fat content now higher then protein content.

  Long-term intake of high proportions of saturated fats leads to imbalances in lipid compositions of all cell membranes, predisposing to inflammatory reactions on the cellular level and decreased cell-to-cell communication ability.

  With the outlined changes in meat, the argument that humans have always been meat eaters, and therefore should continue to be, is invalid and unhealthy.   Recent research has demonstrated the high levels of growth hormones and antibiotics in commercial meat. Unlike earlier assumptions that chicken was the most highly contaminated, beef is now considered to have the highest levels of growth enhancers and antibiotics.

  It is often said that vitamin B12 is rarely present in vegetarian food sources, and as such vegetarians are at risk of being low in this vital nutrient. A healthy digestive system is capable of producing adequate amounts of this vitamin on any diet. B12 is unstable to exposure to heat and some food chemicals. The body stores this water-soluble vitamin in the liver and kidneys. Exposure to some chemicals, even eating a diet containing artificial food additives and preservatives, endangers good B12 level maintenance.

  Aside from physiological considerations inside the body, environmental factors need to be considered in the vegetarian debate. Any manure from animals produced with artificial hormones and antibiotics, has the potential to contaminate soils and waterways as these substances are partially excreted.        Global meat consumption has undergone a fivefold increase in the past fifty years, and population growth has a double effect on climate change.    Deforestation across all continents reduces CO2 conversion into oxygen and the production of methane gas from livestock leads to warming of the atmosphere. A report from the United Nations Food and Agriculture Organization estimates that the livestock production worldwide is responsible for 18% of greenhouse gas emissions; more than the entire transportation sector produce.

  Vegetarian or not, to avoid risk factors for most modern day diseases and to maintain health and well being, the daily food intake deserves consideration. Finding the right balance of vegetarian protein sources or lean, chemical-free meats is half of the equation.

  Digestion will only occur in a non-stressful environment. The autonomic nervous system governs digestive function; relaxed, parasympathetic dominance enhances digestive ability, including stomach acid production; and “stress mode”, sympathetic nervous system dominance, reduces all digestive functions.

  For the individual, awareness of the factors influencing digestion and well being allows choices to benefit the internal balance of themselves and their environment, ensuring continuity of health.


Further Reading

Metabolic Acidity Growth


Hormones and Antibiotics in Commercial Meats


Nutritional Dilemmas of Modern Meats

S.Boyd Eaton, M.D., Marjorie Shostak, Melvin Konner, M.D., Ph.D. Harper &Row Publishers, New York, 1989. The Paleolithic Prescription