Macro-nutrient Digestive Science and Health by Dr. Christie Smirl

Digestion is such a critical component of health and longevity. Key nutrients from carbohydrates, proteins and fats are isolated and absorbed from the gut, then distributed to the entire body. What you chose to put in your mouth determines the health of all your tissues and organ systems that keep us alive and well. Let’s look at the importance of knowing what your food is made of so you can chose the correct fuel for your body and mind. This article contains detailed science, so bear with me, it really helps when eating becomes your personal science rather than entertainment or comfort object.

There are two type of carbohydrates, simple and complex. Simple Carbohydrates provide the body with glucose (simple , C6H12O6) in the form of energy to support the muscles and brain activity. Unused glucose is converted to glycogen and stored in the liver and skeletal muscles for use later, but excess glycogen is stored at adipose (fat) resulting in weight gain. Simple carbohydrates are made of monosaccharides (CnH2nOn), including glucose (dextrose), fructose (levulose), and galactose. Examples of monosaccharide simple carbohydrate foods are:

  • Fruits and fruit juices
  • Honey
  • Syrups such as corn syrup, fructose syrup, high fructose corn syrup (HFCS), agave nectar and blackstrap molasses
  • Wine, beer, sweet mixed drinks
  • Soft drinks, sport drinks, energy drinks, chocolate, candies, sweetened dairy products, desserts

Complex carbohydrates are known as polysaccharides which contain more than ten monosaccharide units, sometimes thousands of polysaccharide units. Let’s look closer at what this means for our nutrition in regards to starchy foods and plant fiber as polysaccharides.

  • Starch is an energy source obtained from plants we eat. Starches are digested by enzymes in the mouth (amylase). Then the stomach mixes in acids and creates chyme. In the first portion of the small intestine (duodenum), the pancreas releases amylase to further breakdown the polysaccharides into a disaccharides. Then small intestine enzymes called lactase, sucrase and maltase break down the disaccharides into monosaccharides to yield glucose. Examples of nutritional starches are:
  • Starchy vegetables such as squash, potatoes, corn, peas, parsnips, plantains, water chestnut and taro.
  • Whole grains and grain flour including amaranth, barley, rice, buckwheat, wheat, millet, oats, muesli, quinoa, rye and spelt.
  • Cellulose is another complex carbohydrate polysaccharide found in plants. Cellulose in plants provides us with dietary plant fiber. A diet rich in fiber helps maintain healthy cholesterol levels, regular bowel movements and weight control just to name a few. So eat your veggies!
    • Examples of high cellulose fiber vegetables are broccoli, Brussels sprouts, cauliflower, cabbage, asparagus, green beans, kale, celery, okra.

Carbohydrates that are not fully digested and absorbed by the small intestine reach the colon where intestinal bacteria contribute to the breakdown process. Fiber, which cannot be digested like other carbohydrates, is excreted in feces (stool, BM), creating a more healthy bowel movement pattern and a myriad of other health benefits such as reducing the risk of cancer.

Digested carbohydrates convert to glucose, but remember, too much glucose mean high circulating insulin. Insulin is a hormone made by the pancreas that allows your body to use sugar (glucose) that you eat for energy or to store glucose for future use. Insulin helps keeps your blood sugar level from getting too high. However, chronic high levels of insulin, hyperinsulinemia can result in a variety of diseases and conditions such

  • Hypertension (high blood pressure)
  • Weight gain and obesity
  • Dyslipidemia (high bad cholesterol)
  • Glucose intolerance leading to type 2 diabetes
  • High uric acid which can lead to gout, joint pain and kidney stones
  • Artherosclerosis (hardening of the arteries)
  • Inflammation, body pain and fatigue


Protein is made of amino acids which are required building blocks for creating and repairing body tissues as well as cellular function. Protein is required for all of the following body processes and structures.

  • DNA components are protein.
  • Hormones and neurotransmitters are proteins.
  • Enzymes are proteins needed to break down and regulate nutrients.
  • Hemoglobin is a protein that combined with iron, transports oxygen in the blood.
  • Myoglobin and elastin are the two main proteins in muscle fibers.
  • Bones are mainly proteins, with calcium, magnesium and phosphate.
  • Antibodies which circulate in your blood to protect you against viruses
  • Keratin which forms your hair and nails is a protein.

There are plant and animal based protein sources.

  • Plant proteins are abundant including seeds (pumpkin, chia, hemp), edamame (soy beans), tempeh (soy), tofu (soy), lentils, beans, nuts, wild rice, peas, chickpeas, spinach, broccoli, quinoa, buckwheat, spirulina to name a few.
  • Animal proteins are eggs, meat, blood, bone broth, bone marrow and milk.

Protein is digested in the stomach by an enzyme called pepsin and in the small intestine by the pancreatic enzymes called trypsin, chymotrypsin, and carboxypeptidase. Excessive protein goes through gluconeogenesis and is broken down into glucose. A small chicken breast with about 100 grams of protein could produce about 50 grams of glucose! So keep your protein intake within your targeted macronutrient goals. Plus, too much intake of proteins can increase the risk of kidney disease.

Fats serve both structural and metabolic functions. Fats are made of triglycerides (esters of three fatty acid chains and alcohol glycerol). Fats are emulsified in the small intestine by bile from the gallbladder, then further broken down by bile salts and pancreatic enzymes called lipase. There are two types of fats: saturated and unsaturated. and a further subcategory for fatty acids according to their size: short chain triglycerides (SCT), medium chain triglycerides (MCT) and long chain triglycerides (LCT).

  • Saturated fatty acids are needed to stabilize the myelin sheath, immune system and brain protection. Saturated fatty acids do not have C=C double bonds. Instead, the formula is CH3(CH2)nCOOH, with variations in n. Types of saturated fatty acids are capric acid (MCT), lauric acid (MCT), myristic acid (LCT), palmitic acid (LCT), stearic acid (LCT), arachidic acid (LCT), behenic acid (LCT), lignoceric acid (LCT). These are solid at room temperature and stable when cooking. Examples are
    • Meat, milk (cheese, butter, yogurt, creams) and pork lard. Plant sources include coconut and palm oil.
  • Unsaturated fatty acids have one or more C=C double bond. The C=C double bonds can make monounsaturated or transfats.
    • Polyunsaturated fatty acids have more delicate stability and contain eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These are anti-inflammatory by increasing the use of prostaglandins 1 and 3.
      • Omega 6 gamma linoleic acid can be an unfavorable fatty acid that stimulates prostaglandins #2 which trigger inflammation when in too high of ratio. Examples are canola oil, flaxseed, hempseed oil, grapeseed oil, pumpkin seeds, raw sunflower seeds, pine nuts, pistachios, borage oil, evening primrose oil, black currant seed oil, acai. These should not be used for high heat cooking.
      • Omega 9 oleic acid monounsaturated fat is stable and can replace omega 3 and 6. Examples are olive oil, nuts, seeds vegetable oils (olive, peanut, safflower, sunflower, soy, and corn) and avocados. These fats are liquid at room temperature, but they solidify in the refrigerator. These are okay for cooking, but only at very low temperatures.
      • Omega 7 palmitoleic acid is important because it reduces inflammation and increases insulin sensitivity which is a good thing. Sources of omega 7 are found in salmon, anchovy, tuna, sardines, mackerel, trout, macadamia nuts and sea buckthorn oil.
    • Monounsaturated fatty acids are plant based fats that are protective, anti-inflammatory anti-oxidants.
  • Trans-unsaturated fatty acids (TFA) are chemically modified in a laboratory through the hydrogenation process. Trans fats block propagandists #1 and #3, create inflammation, raise low density lipoprotein (LDL, “bad cholesterol”) and reduce high density lipoproteins (HDL, “good cholesterol”). Growing evidence also suggests that TFA also increase visceral fat, insulin resistance, increase cardiovascular risk factors. Examples are
    • Margarine and shortening (Crisco)….. stay away from these all together.

Okay. After all that science, what does it all mean in regards to your health. Too many people consume far too much glucose in the form of simple carbohydrates, complex carbohydrates and protein. Remember that excessive glucose causes high insulin levels, weight gain and multiple disease processes discussed above. Trans-fats are dominant in junk foods and fast foods and are harmful to your overall health. Start looking at your food in terms of fuel and life source. My biggest recommendations are:

  • Eat for your health and longevity, not for entertainment or stimulation.
  • Eat whole food ingredients.
  • Read food labels and be aware of transfats and sugar/carbohydrates, not just calories.
  • Start tracking your macronutrients (carbohydrates, fats, proteins) on a food app such as My Fitness Pal to study your nutritional patterns and locate areas that can be improved.
  • Reduce processed foods, junk foods, canned foods, frozen foods, boxed foods, artificial colors, artificial sweeteners, artificial preservatives, fast food and glucose (sugars from carbohydrates or proteins).
  • Calculate how many calories you eat and determine if it is proper for your body size, age and activity level.
  • Be accountable for what you eat and cultivate motivation and discipline where needed.
  • For me the most important determinant of a healthier nutritional profile is planning.
    • Determine what foods fuel your body.
    • Make a shopping list and go get the whole ingredients.
    • Eat simple and clean.
    • Prepare your food at home.
    • Take your meals with you at work, school or events. Remember that the food industry makes billions of dollars off making sure your food is tasty, laden with chemicals, additives, salts and hidden sugars to make you “crave” more. Food addiction and irresponsibility is an epidemic. Don’t become a statistic of disease due to being too busy to take care of the body in which your soul inhabits.

Dr. Christie Smirl has over 25 years of medical experience. She completed a Doctorate of Ayurvedic Medicine from American University of Complimentary Medicine as well as aNurse Practitioner and Master of Science from Loma Linda University. Dr. Christie is also an E-RYT 500 Yoga Teacher Trainer YACEP, Reiki Master/Teacher, Tantric Energy Healer and Musician.

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One Comment Add yours

  1. Ismoon says:

    Wonderful and educational – thank you Dr. Christie.

    Liked by 1 person

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