July 15th, 2013 by Digestive Detective
“Your nutrition is more than the amount of fat or number of carbs. Numerous studies show the critical role that micronutrients - vitamins, minerals, phytochemicals - have in the body. If you're solely counting calories or checking carbs, you are doing your cells a disservice.”
Those looking to track their nutrition or diet often create too narrow a focus on the macronutrients: carbs, fats, and proteins. While these dietary constituents are important, they are often the sole focus while the vital micronutrient content of meals/foods is frequently ignored. Part one in this series of articles on the essentiality of micronutrients in the diet provides a brief overview of important metabolic pathways and begins to explore key nutrients that are directly involved in proper metabolism.
A nutrient-poor diet that only considers how many calories or how many carbs are in each meal is bound to fail you. Should you take calories into consideration – absolutely. Would it be wise to consider the carb content and source of your meals – definitely. These factors matter but micronutrients matter as much if not more. The manner in which our physiology consumes and utilizes the food we take in is a very complex process with a variety of cellular functions and aspects of metabolism occurring on a regular basis. This process is also very dependent upon a number of micronutrients to act as cofactors – compounds that are necessary for enzymes to perform their jobs of catalyzing the reactions that lead to the macronutrients we take in (proteins, carbs and fats) being transformed into usable energy. Without the presence or with an insufficient presence of these critical micronutrients, then certain metabolic processes may not occur well if at all – leading to storage of excess calories. In order to illustrate this point and highlight several key nutrients that ensure proper use of the foods we consume, let’s first take a look at a simple overview of some of the primary metabolic pathways.
Many tissues of the body need a steady supply of glucose – the sugar that is an end product of carbohydrates. When we eat carbohydrates, our bodies need to get the glucose out of the bloodstream and into our cells. The process by which this is achieved is known as glycolysis (glyco – meaning glucose; lysis – meaning “break down”). Glycolysis involves splitting a 6-carbon molecule of glucose into two, 3-carbon molecules of pyruvate that enter the mitochondria (the “furnaces” of our cells) and eventually continue into the citric acid cycle.
Citric Acid Cycle
The citric acid cycle is a key component of the metabolic pathway by which our bodies generate energy. Through the breakdown of sugars, fats, and proteins, a two carbon organic product acetyl-CoA is produced. One of the primary sources of acetyl-CoA is sugars that are broken down by glycolysis to produce pyruvate that in turn is decarboxylated by the enzyme pyruvate dehydrogenase (more to come on this nutrient-dependent, enzyme complex later). The citric acid cycle is a converging point for the breakdown (catabolism) of proteins and fats as well:
Proteins: In protein catabolism, proteins are broken down into their constituent amino acids. The backbone of these amino acids can become a source of energy by being converted to acetyl-CoA and entering into the citric acid cycle.
Fats: In fat catabolism, triglycerides are broken down into fatty acids and glycerol. In the liver the glycerol can be converted into glucose. The fatty acid portions can be broken down through a process known as beta oxidation, which results in acetyl-CoA, usable in the citric acid cycle. The citric cycle itself generates energy (ATP) and also produces NADH – a nutrient compound that carries electrons to the electron transport chain for additional energy production.
Electron Transport Chain
A powerhouse of energy production, the electron transport chain results in a large number of ATP being generated for energy. This process involved several complexes (a few that require nutrient cofactors as we’ll see later) that function to donate electrons and move them along the chain until, in a final reaction with hydrogen and oxygen, high amounts of ATP are formed.
As I alluded to in the examples from above, these metabolic pathways are often dependent upon reactions catalyzed by specific enzymes; in turn, these enzymes are often dependent upon specific nutrient cofactors. The dependency of an enzyme on a particular cofactor means that in the absence of that cofactor or insufficient quantity of it, the enzyme function will be compromised. Compromised function of an enzyme in a metabolic pathway means the entire pathway will likely not function optimally, leaving excess quantities of the substrate (compound being transformed) and backing up, slowing or altogether stopping the process from occurring. In basic terms, this means is that the sugar, protein or fat that your body is trying to burn for fuel is not being used efficiently. The result: low energy, excess storage of calories, and poor cellular function. The health of the cell = the health of the body. In other words, the result is your body becoming tired, fat, and sick. Let’s identify some of the key players in these metabolic pathways who, if absent or insufficient in the system, can lead to the scenario above:
Magnesium is involved in over 300 processes in the body, including ATP synthesis (energy production). Several enzymes involved in glycolysis are magnesium-dependent. Magnesium is also involved in the citric acid cycle and beta-oxidation – the break down and metabolism of fatty acids. Several studies over the past few years have exhibited low magnesium intake and suboptimal magnesium status among adults. This is thought to be due in part to insufficient consumption of magnesium-rich foods, along with competitive inhibitors such as certain drugs. Drugs that may induce magnesium deficiency include:
- Antibiotics (eg amphotericin B)
- Asthmatic medications
Magnesium deficiency or insufficiency is associated with diabetes, hypertension, and cardiovascular disease and may manifest with symptoms that include fatigue, irritability, weakness, muscle tightness or spasms, dysmenorrhea, hypertension, nerve conduction issues, insomnia, sugar cravings, and anxiety. If you suspect deficiency or want to get tested, ask your physician to run a red blood cell magnesium test.
To ensure optimal levels of magnesium in the body, incorporate these foods into your diet:
- Pumpkin seeds
- Swiss chard
- Black beans (soaked)
- Brazil nuts
In the next article in this series, we’ll examine the role of the “B vitamins” in energy production and weight maintenance.