The art of Chewing: Update (Newsletter Summer Edition 2015)

Previously published on
https://www.exquisiteprivatechef.co.uk/its-all-about-food

Readers who have followed me for all these past years, will all agree that I am an advocator of mindful eating and chewing food properly. I have written an extensive article chewing in my Spring Edition - Part 2 (2013): "To Chew or Not To Chew - That is the question… Is it really important and how long should we chew for?”

I thought this needed a much clearer update.

To understand the actual mechanism of chewing it is important to understand food first, their molecular composition and how they are broken down so that nutrients can be extracted and absorbed. Although, the objective of my newsletter is to keep subject very clear, concise and understandable by everyone, I will not go into chemistry but will explain the main phases of digestion for all Macronutrients (Fat, Carbohydrates, Protein).  

Digestion of Proteins: even though the digestion only truly begins in the stomach, it is initiated by chewing so that stomach can work efficiently at breaking down large Protein molecules into smaller molecules: Amino Acids. 

   The acidic environment of the Stomach favours protein Denaturation. Amino Acids are easier to extract from Denatured proteins. The primary enzyme (also a Protein) of the stomach is Pepsin, which remarkably, is maximally active at pH 2. Thus, pepsin can be active in the highly acidic environment of the stomach, even though other proteins undergo Denaturation there.

   Protein degradation (into free amino acids) continues in the intestine owing to the activity of enzymes secreted by the Pancreas. Digestion is further enhanced by other enzymes (Proteases), which are located in the plasma membrane of the intestinal cells. Single amino acids, as well as small molecules of 2–3 Amino Acids linked together, are transported into the intestinal cells, and subsequently released into the blood for absorption by other tissues 


Digestion of Carbohydrates – from Sugars, Starch, or Glycogen (very long molecule of Glucose from animal sources)

Salivary Amylase starts breaking down large molecules (≈10% digestion in the mouth), and then is deactivated by the acidic pH of stomach. Pancreatic Amylase then takes over the digestion process in the Small Intestine, and Sucrase, Maltase and Lactase in the mucosal cells in the Jejunum brush border complete digestion.  


Digestion of Fats:

Gastric Lipase starts digestion of fats (≈10% – emulsion is not happening so not much breakdown), in the Duodenum bile salts emulsify fat (break down large droplets of fat into smaller droplets), so that Pancreatic Lipase can breaks triglycerides (smaller droplets consisting of 3 molecules of Fatty Acids attached to a molecule of Glycerol) into Fatty Acids (FAs) and Glycerol. Free FAs enter membrane lining of the Small Intestine and diffuse into the cell, and are reconstructed into Triglycerides, along with cholesterol and phospholipids, forming Chylomicrons and pass into the lacteal of the villi.

Chewing has no impact on fat digestion… 


Digestion of Other Compounds: 

-     Brassicas (Broccoli, Cabbage, cauliflower, Brussels Sprouts) – excellent source of Glucosinolates, broken down (by hydrolysis/chewing) into powerful metabolites: Indole-3-Carbinol (I3C – directly inhibits tumour’s ability to supply itself with blood) and Isothiocyanates (induces cancer cells to commit suicide). 
   So now is another reason to love the Greens, but considering that Cruciferous also modulate liver enzymes activity (increase natural detox pathways), inhibit carcinogen-activating Phase I enzymes, and induce carcinogen-detoxifying Phase II enzymes. 
Broccoli is also an excellent source of Vit. C, B2, B6, Folate, dietary fibre and minerals (Mn, K, Mg, P)

-     Garlic – S-allyl (water-soluble sulphur compounds): protect cells from toxic chemicals, and Allixin (Flavonoids – antibacterial/antifungal), Selenium. Together they decrease cholesterol (LDL/Triglycerides) levels, protect LDL from oxidation/prevent cell injury in blood vessels. Exposition to Oxygen makes these compounds very powerful Antioxidants (crush Garlic and keep aside for 10 minutes, chew well). Garlic prevents mutation/binding of carcinogens to DNA, activates destruction of carcinogens, increase immune cells activity.

 
So what do we need to take from this?

First and Foremost, Digestion starts with our brains. When we think of food, look at food, smell food, and touch food, these sensorial information reach the brains, which then initiates digestive processes, such as salivation (topping up your stomach juices), digestive enzyme secretion (ready to break down food), the body relaxes (digestion is set to a halt in period of acute stress, and hugely affected in period of chronic stress), and many others. This is one of the reasons why eating mindfully helps digestion. 

   When you are ready to eat, make the effort to present your food beautifully, even if you are just cooking for yourself – food should make you happy, because your body knows it is getting what it needs! 

   Take a deep breath, and then look at your plate, smell the aromas, and feel gratitude. Then take your time chewing, experiencing all the different flavours and textures in the food. Put your fork or spoon down between bites, and visualise how your food is nourishing you.

   Chewing sufficiently can hugely diminish digestive discomfort. The saliva that mixes with our food while chewing is equipped with enzymes to start breaking down the food, especially carbohydrates for better absorption. Some experts say chewing 30+ odd times is ideal; some say 10 times is enough. I have repeated several times that counting should be avoided at any cost, as it takes away the joy of eating, and counting set your mind on a task: a job it should not be doing. Chewing is not a job it is a pleasure! 

More saliva less drinking!

By keeping water intake to a minimum during a meal it will allow saliva to do its job efficiently, without being diluted, same as the Gastric Juices. Furthermore, cold drinks slow down digestion of food in the stomach, thus creates fermentation, especially if you have eaten sugary foods, including fruits.  

   Drink a Large glass of water, or a cup of green tea, 10 minutes prior and resume drinking water 2 hours after a meal.

Illustration: Olivier Sanchez (inspired from Biomedicine books, and medical dictionaries)

Illustration from: http://www.ceresproject.org/digestion-illustration_acs.jpg

Chewing and Absorption of nutrients:

Carbohydrates

Function: Primary fuel for Energy production, limited form of stored energy (Glycogen), Indigestible CHOs (cellulose) important source of fibre needed for proper bowel function 

Optimal Daily intake: 75–150g – from vegetables and whole grains

Common signs of digestion: gas and bloating. 

“Treatment”: Soaking and double-boiling beans (always cook with seaweed), and very light cooking of cruciferous

Sluggish digestion? Check out for: fibre intake, stool frequency, quality, quantity, easy/difficult to pass, fluid intake, laxative use, exercise?


Proteins

Function: INVOLVED IN VIRTUALLY EVERY CELL FUNCTIONS (antibodies, enzymes, muscles contraction/movement, hormones, structural (Collagen), transport (Haemoglobin), membrane of every body cells)

Estimated Daily intake (g/kg body weight): 3–4 years old: 1.09; 9–19: 0.95–0.99; >19 years old: 0.75

Absorption: Pepsin (gastric juice), Proteolytic enzymes (Pancreas and mucosa of Small Intestine), and Vitamin B6 (carrier, increase HCL (gastric juice) production, and a co-factor in synthesis of certain AAs)


Fats (Lipids)

Triglycerides: main form of stored fats in the body made up of 3 FAs attached to Glycerol. Needed for lipids transport, energy production, 

Phospholipids: make up the membrane of every body cell, 

Sterols: basis for steroid and reproductive hormones, 

Fatty Acids (FAs): +/- long carbon chains. The most common form of fat in the body

Saturated Fats (SFAs) are not essential as can be made by body. 

Polyunsaturated Fatty Acids (PUFAs): Essential FAs Omega-3 (Alpha Linolenic Acid (ALA) – Flax/Linseeds, Hemps, canola, Soybean, Walnut and mustard oils and dark green leafy vegetables, Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) – cold water fish), Omega-6 (Linoleic Acid (LA) ž Gama Linolenic Acid (GLA) ž Dihomo-Gamma Linolenic Acid (DGLA) ž Arachidonic Acid (AA) – seeds and seed oils). Other PUFAs: Omega-9 (Oleic Acid – Olive, canola, peanut and avocado oil)

Optimal Daily intake: <20g – for average weight (SFAs), 1–3 g (Omega-3s) 

Function: Carrying fat-soluble Vitamins; formation of every cell membranes, brain tissue, nerve sheath and bone marrow; hormone production; regulation of body temperature; protection/insulation; fuel reserve; anti-inflammatory (i.e. Omega-3s). 

N.B. Trans Fatty Acids (TFAs) – created by increased heat (>160˚c), and partial Hydrogenation (margarine and baked products)

N.B. Cholesterol: only from animal fats (and also) made by the liver – necessary for steroid hormones, nerves sheath (improved nerves transmission) and cell membranes. 

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Sources

Berg, JM. Tymoczko, JL. Stryer, L. (2002). Biochemistry, 5th edition. 5th ed. New York: W H Freeman. Section 23.1.
Higdon, JV. Barbara Delage, B. Williams, DE. Dashwood, RH. (2007). Cruciferous Vegetables and Human Cancer Risk: Epidemiologic Evidence and Mechanistic Basis. Pharmacological Research. 55 (3), pp.224–236.
UK RNIs, available at: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/384775/familyfood-method-rni-11dec14.pdf