What are carbohydrates?
Behind those 4 syllabes is hiding a word each one of us knows very well. Even if we identify it better in its cube-shape when we drop it in our coffee or when it falls on our waffles in an elegant powdery fashion, sugar is also present in many other foods, without being denounced by their taste. Whereas sugar is merely an ingredient for many of us, it is actually a generic word that encompasses a whole family of tens of molecules, concealed by tens of complicated names. We also refer to this group as glucides, carbohydrates or even carbs for those in the know. In fact, if we had to find a common point between pasta, dough, oat flakes, bread, rice, potatoes, fruits and honey, it would be their high content of sugar!
So carbohydrates are the nutritional category for sugars, and they can be simple or complex depending on their structure, and more specifically on the bonds that link their molecules together. Glucose, fructose and galactose are the three basic different types of simple sugars called monosaccharides, and when 2 of them are linked together, they form bigger molecules called disaccharides, like lactose, maltose or sucrose. Beyond three sugar molecules assembled together, we talk about complex sugars. When 3 to 10 sugar merge, they form oligosaccharides, while polysaccharides contain more than 10 sugar molecules. This shows us a glimpse of the diversity of sugars found in our diet.
Do we need carbohydrates?
During digestion, carbohydrates are broken down into their monosaccharides building blocks that our cells get energy from. Along with proteins and fat, they are one of the three pillars of our energy supply. So carbs not only fulfill a portion of our energy requirements, but also provide the necessary glucose supply for specific tissues like the brain, red blood cells, and the developing fetus. The problem of our modern diet is that consumption of sugars overtook fat and proteins and reversed the original proportions of each of those three essential resources. This tendency is very likely to be the result from the prevailing confusion regarding the different forms of sugar and therefore its excessive consumption. But even if we are no longer sure whether or not we are eating sugar, our body is so clever that it recognizes every single carbohydrate molecule.
What is the effect of sugars on our bodies?
Interestingly, our digestive tract does not handle every type of carbohydrate in the same way. Fibers, which are a polysaccharide, present a structure that can not be broken down by the body. They are found in vegetables, fruits and whole grains and have the capacity to slow down the passing of glucose from your intestines to the blood. Foods that are rich in fiber therefore have a low glycemic index. On the contrary, starches are another form of polysaccharide found in crackers, white bread, pasta, rice and potatoes among many other ingredients. The more refined they are, the easier they are cleaved by enzymes in the gastrointestinal tract, allowing a quick digestion coupled with rapid glucose increase in the blood. When their effects are not counterbalanced by fiber, fat or protein content, some starchy foods thus may have a similar effect on blood glucose as drinking a soda, full of simple sugars. Such foods are said to have a high glycemic index.
When carbs enter the bloodstream, according to their nature, they can cause the blood sugar levels to spike. Once in the blood, they have to be transferred into our tissue cells to be processed and converted into energy, or be stored for a rainy day. This whole process is mediated by insulin, a hormone synthesized in the pancreas, and that prompts our cells to let glucose in. In other words, insulin is in charge of lowering blood sugar by permitting its absorption into the cells, so that they can utilize it. The more a given unit of insulin lowers blood sugar, the more the body is sensitive to insulin. Conversely, insulin resistance leads to an accumulation of blood sugar while insulin continues to rise. Chronically consuming excessive quantities of carbohydrates may lead to insulin resistance and subsequent metabolic syndrome, associated with increased risk of cardiovascular diseases and type II diabetes.
In short, if we go over our food with a fine-tooth comb, we will realize just how much sugars have become the improper base of our diet. While they represent an indispensable source of energy, we must learn to recognize, choose and limit their consumption. Another key to control our sugar intake is to understand its power over the brain.
What is fat?
Fat, together with carbohydrates and proteins make up the triptych of our energy supply. When it comes to fat, we might come across a lot of complex, controversial and contradictory information, so let’s try to shed some light on the topic. From a chemical perspective, fats are called lipids and in our body, are mainly stored as molecules called triglycerides. They consist of a glycerol backbone tied up to three fatty acid chains held together through different linkages. Fatty acids with only single bonds are called saturated, and those with one or more double bonds are called unsaturated. The length and differences in the structure of these fatty acids determine the interactions between the fat molecules and the body, making them sometimes essential and sometimes dangerous.
Do we need fat?
Beyond being a precious source of energy (and should arguably be the major contributor in our diet), fats are also a critical component of cells and tissues, a precursor of cell communication, they support immune function, they protect our organs and help absorb essential vitamins among many other essential functions. You might also be willing to know that 70% of our brains are made up of fat, and that healthy fats are crucial to enhance brain plasticity and preserve memory.
What fat should we eat?
The most commonly found fat molecules in nature are unsaturated fats. Due to their molecular structure consisting of a cis configuration, they appear in a liquid form at room temperature and are categorized as unstable due to their increased susceptibility to oxidation. Unsaturated fats can be further categorized based on the number of carbon atoms counted from their tail (or the omega end of the molecule) to the location of the first double bond of the fatty acid. You may have guessed it, we are talking about the famous omegas here! To spice up the discussion, omegas can be further split into
- Monounsaturated fatty acids that present with 1 double bond in their carbon chain
- The most notable of them are omega 9 that include oleic acid. It is found in olive oil, avocados, almonds or macadamias but can also be made by the human body. Along with saturated fats, they form the core structural fats of the body. They are known to reduce inflammation, lower blood pressure and reduce the incidence of cardiovascular accidents.
- Polyunsaturated fats that present with 2 or more double bonds in their carbon chain
- Polyunsaturated fats have been shown to regulate gene expression and aid cell function. But due to their higher number of double bonds, unsaturated fats are more susceptible to oxidative damage, which renders them unsuitable for cooking at high temperatures. When exposed to high heat, unsaturated fats can produce free radicals and aldehydes that may damage cells. However, some types of refined seed oils, such as avocado oil, peanut oil, and safflower oil, have a high smoke point which makes them more stable at high temperatures and hence are used in cooking, nonetheless, as you will find out later, you may want to avoid those. The most important polyunsaturated fats are:
- Omega 3 – includes ALA (alpha-linolenic acid) found in flaxseed and walnuts. It can be metabolised into EPA and DHA to a certain extent, but this conversion turns out to be inefficient in many people depending on their age, diet and health status. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are both sources of omega 3 found mainly in anchovies, mackerel, salmon and sardines. They can also be found in grass fed beef and in eggs in lesser quantities. They contribute to the development of eyes and brain in kids and support cognitive function in elderly. Deficiencies in these nutrients have been linked to inflammatory diseases.
- Omega 6 – includes linoleic acid (LA), present in industrialized vegetable oils like soy, sunflower and safflower oils. It is also present in nuts and poultry. Omega 6 has become problematic as industrialized vegetable or seed oils have flooded our diets, being now ubiquitous and overwhelming our omega 3 : omega 6 ratio. Moreover, consuming the pure oil extract from these seeds is a relatively recent development in human history and does not align with our evolutionary dietary habits. Historically, we have consumed these seeds in their whole form for millennia, which limited our intake of the Omega 6 oil. The extraction of oil from these seeds allows us to consume larger amounts of it in a shorter amount of time. Excessive consumption of omega 6 has been associated with gut dysbiosis and inflammation, weight gain, liver disease, autoimmune disorder and cancer. Omega 6 also includes arachidonic acid (ARA) found in fish, meat and eggs. It is involved in cell signaling and acts as vasodilator. It is also necessary for the growth and repair of skeletal muscle tissue and along with DHA, it is one of the most abundant fatty acids in the brain.
Now think about butter or lard as being a quintessential example of natural saturated fat. They get their solid consistency from the absence of double bonds in their fatty acids, which enables them to pack together. They are not as prone to oxidative damage as unsaturated fats, which indicates them as good cooking oils (up to their smoke point). In the last decades, the medical community has advocated the belief that high cholesterol poses a substantial risk for coronary heart disease, and that consuming a diet that is rich in saturated fat and cholesterol can cause heart disease. However, recent higher quality studies do not validate this hypothesis. Despite an abundance of contradictory evidence, this notion is still widely accepted as the truth by many physicians and the general public. Back in our hunter-gatherers’ days, we primarily relied on saturated fats as a fuel source, and therefore, our bodies have developed a strong familiarity with it over time, enabling us to process it efficiently. When insulin levels are in a normal range, there is no known toxicity associated with consuming high levels of saturated fats, unlike polyunsaturated fats and carbohydrates. Moreover, long-chain saturated fats are more efficiently utilized by the body as an energy source compared to polyunsaturated fats, and their conversion into energy does not result in the production of harmful by-products.
Saturated fats can be divided into:
- Long-chain saturated fats (myristic, palmitic acid and stearic acid) are found mainly in milk and ruminant meat (like butter or lard). They correspond to 75 to 80% of the fatty acids present in most cells and primary storage of energy in humans. They help with calcium utilization, hormone metabolism, support the immune system and help carry and absorb fat soluble vitamins.
- Medium-chain saturated fats (lauric, capric, caprylic and caproic acid), found in coconut and breast milk. They are a great source of digestible energy, stimulate metabolism, have antimicrobial properties and are particularly nutritive to the brain.
- Short-chain butyric and propionic acid are found mainly in the gut and are produced by our microbiome as a by-product of dietary fiber fermentation. It may help protect the gut lining and modulate the immune system.
Our last category encompasses trans fats. Their main distinctive sign to pay attention to is whether or not they are naturally produced. Their trans nature results from the reconfiguration of part of their original double bonds. These are unsaturated fats, made saturated through a chemical process.
Generally, trans fats are produced through a process called partial hydrogenation that has been observed to happen naturally in animals’ digestive tracts, then referred to as biohydrogenation. This explains why saturated trans fats are naturally present in grass-fed animal meat and dairy products under the form of CLA (conjugated linoleic fat). Against all odds, CLA (sourced from grass-fed and organic animal products) has been associated with a decreased risk of cardiovascular disease, enhanced insulin sensitivity and subsequent prevention of type II diabetes and reduced cancer incidence!
Artificially modified unsaturated fats or industrial trans fats do not go rancid, are more stable during frying and can change the texture of foods. However, they have been proven to promote inflammation and contribute to coronary heart disease and are nowadays largely banned in Northern America and Europe!!
Long story short, if you had to remember 5 recommendations from this article, they should be:
- Opt for natural fats, favor organic sources and enjoy savory food
- Savor liquid fats like olive oil raw, for dressing or seasoning, and cook with solid and stable fats like lard, coconut oil and even butter (but beware of their smoke point)
- Pay attention to your omega 3 : omega 6 ratio and opt for natural omega 6 sources like whole nuts and seeds
- Stay away from industrial fats and processed vegetable and seed oils
- Balance up your fat calorie sources with your carbs, keeping in mind the importance of fats as an energy contributor.
What are proteins?
Proteins are complex biomolecules made up of chains of amino acids bound together by peptide bonds. Depending upon their specific sequence, the three-dimensional structure of a protein determines its unique functions within the cells of our bodies. Although there are hundreds of amino acids in nature, humans use only about 20 of them to build up the proteins we need.
Do we need proteins?
Proteins are a vital part of the human diet and can be found in various foods such as seafood, legumes, nuts, meats, seeds, dairy, and eggs. They are such a crucial nutrient that the brain has specific mechanisms that make us crave them whenever we need more. When we consume and digest protein, it gets broken down to its amino acids building blocks, and then reshaped into new proteins in our bodies. Proteins perform several tasks, such as growth and repair, contribute to our cell structure, fight infections, aid in cell division, and assist in the formation of hormones and other essential molecules.
The daily protein requirement for healthy adults is estimated to be between 0.80 and 1 grams per kilogram of body weight, but this can vary based on age, gender, physical activity level, and other factors. Pregnant and breastfeeding women, athletes, and older adults may for instance require more protein.
Proteins have further been proven to have a wide range of positive side effects. First, they help in weight loss as they are the most satiating macronutrient. Then, they have a stabilizing effect on blood sugar, improve sleep and sharpen brain function. Finally, proteins are the nutrient that builds and repairs muscle. Their adequate intake is thereby an utmost requirement in athletes, but is also particularly indicated in the elderly and chronically ill people to compensate for muscle wasting and prevent further tissue breakdown
What proteins should we choose?
The 20 amino acids used by humans include nine essential amino acids, six conditionally essential amino acids, and five non-essential amino acids. The essential amino acids cannot be synthesized by the body and must be obtained from whole food. So animal-based protein foods usually provide all nine essential amino acids, while most plant foods, including legumes, nuts, whole grains, and seeds, have high amounts of some amino acids and low amounts of others. However, some plant-based protein sources, like soy, provide all nine essential amino acids too, although are less bioavailable than in animal products.
Some people present with intolerances and suffer from low stomach acid, bile insufficiency, or other digestive problems that prevent them from easily digesting large amounts of animal proteins. Ultimately, such patients should focus on their gut health to restore their proper digestive function and to make sure they can absorb the quantity of protein they need.