Think back to the very first time you learned about the human body. Perhaps it was a class in elementary school where you began delving into the basics of each of the organs and their essential functions. It’s likely that in that class, and many times since then, you learned about nutrition alongside anatomy and physiology, how foods are broken down and digested into their most fundamental components -- carbohydrates, fats, and proteins -- which are then used by the body to carry out metabolic functions.
As a brief overview, carbohydrates are simple sugars that give your body an efficient energy source. They are the primary fuel for your muscles and important organs, such as the brain. Fats, on the other hand, are the body's main storage form of energy and are involved in countless physiological processes, including hormonal regulation and neuronal communication. Lastly, proteins are heavily involved in the structure and function of many of the body’s tissues and organs and catalyze many biochemical reactions that are important for cellular growth and energy production, amongst other key functions.
For many, these macronutrients are all too familiar and are often a key focus when building a healthy diet. However, the importance of vitamins and minerals, known as micronutrients, seems to be much less emphasized in the classroom and in society. Of course, certain minerals are more well-known than others. For example, we’ve all heard of the importance of having enough iron in our diets, but what about selenium, manganese, or chromium? Indeed, micronutrients are equally as essential to the health of the human body. Put simply, nearly every bodily process requires micronutrients to function efficiently, if at all.
This is exemplified by the countless diseases that can develop because of a particular nutrient deficiency. Consider scurvy, one of the oldest-known nutritional disorders of all time. Common during long-term sea voyages such as Christopher Columbus’, the disease caused severe agony and pain amongst crew members. The first symptom was often intense, debilitating lethargy, aching joints, swollen arms and legs, and easily bruised skin. As the disease progressed, gum rot and internal hemorrhaging began to occur. Left untreated, death was inevitable due to a sudden hemorrhage near the heart or brain.
Between Columbus’ exploration of the seas and the invention of steam engines in the mid-19th century, scurvy took more than two million lives. Unfortunately, no one seemed to understand the cause of scurvy nor what could cure it. While the first probable case of scurvy dates back to 3800 BCE, it wasn’t until 1753 when Scottish naval surgeon James Lind noticed that scurvy mysteriously seemed curable and even preventable by consuming lemon or orange juice. Only in 1928 was it pinpointed that scurvy developed because of a simple vitamin C deficiency.
Vitamin C is a micronutrient vital to the formation of collagen, a component of healthy body tissue. Something so simple yet so crucial as that single mineral ended up determining the fates of millions of people. Given some fresh vegetables or an orange, foods we now know are rich in vitamin C, these sailors all could have avoided the gruesome endings they faced.
Now, research has shown time and time again the essential role that micronutrients play in our bodies. Energy production, oxygen transport, immune function, tissue growth and repair are physiological processes that recruit micronutrients. Furthermore, exercise heavily relies on micronutrients, as many metabolic pathways that become stressed during high-capacity physical work utilize these nutrients.
In addition, antioxidants, composed of many vitamins and minerals, protect the body against free radical damage during exercise. If not kept in check, oxidative stress can ultimately lead to strained muscle tissue and various diseases such as cancer and heart disease. By including antioxidants in one’s diet, muscle damage and fatigue can be avoided, and aerobic capacity can be improved.
One might assume that with the development of modern science, which has led to a detailed understanding of physiology and biochemical processes, and global agriculture, which enables access to a wide variety of food staples, nutrient deficiency would be nearly impossible. Unfortunately, this isn’t the case. Micronutrient deficiencies affect two billion people globally, amounting to 30% of the entire human population. Iron, zinc, copper, folic acid, and vitamin B9 are amongst the more common micronutrients that, when deficient, can cause serious, life-long health problems. For example, in South Asia, it’s estimated that 50% of pregnant women have an iron deficiency, which can cause low birth weight, pregnancy complications, and other birth defects. Millions of children in impoverished regions of India and China also face iron deficiency that causes severely stunted growth. Around 45% of deaths among children under the age of 5 in low- and middle-income countries are linked to undernutrition.
Although micronutrient deficiencies are prevalent in developing nations, they are also quite common in developed countries. In the United States, most of the population fails to follow a healthy eating pattern, leading to an obesity epidemic affecting all age groups. On top of that, about one-half of American adults develop at least one preventable chronic disease. This is partially attributable to Americans falling short of the recommended amount of vegetables, with 80% not consuming the suggested intake.
What further complicates the problem is that micronutrient deficiencies can be particularly difficult to detect clinically. Symptoms of deficiency include fatigue and impaired cognitive function, memory, and mood -- all of which could simultaneously be a result of a poor night’s sleep or a particularly stressful day. This is why micronutrient deficiencies are often called “hidden hunger,” as symptoms only manifest once the deficiency has reached a certain point of severity.
The long-term effects of micronutrient deficiency are certainly foreboding. Lack of Vitamin D can lead to osteoporosis; not consuming enough potassium can ultimately contribute to the development of hypertension and heart disease; lack of dietary fiber in one’s diet negatively impacts colonic health.
So, which vitamin deficiencies are of focus in the United States? Amongst many others, calcium, vitamin D, magnesium, potassium, and vitamin E are a few that have all been identified as the more common deficiencies within the US.
Calcium is a key micronutrient for bone health and one of the body's most abundant minerals. Yet, according to dietary surveys, many Americans, more than 40% of the US population, fail to consume sufficient calcium through diet alone. Calcium is particularly important for athletes as it plays a key role in muscle contraction, stabilization of blood pressure, hormone secretion, nervous system function, and maintenance of a regular heartbeat.
Vitamin D is intricately involved in calcium absorption and is equally important to ensure one is consuming in sufficient amounts. In addition, vitamin D acts as a hormone and is synthesized by our skin through UV rays, making sunshine a primary source of this vitamin. Finally, research shows that Vitamin D is involved in bone health and a foundation for a strong immune system capable of preventing illness. Yet dietary surveys indicate a high prevalence of Vitamin D deficiency amongst Americans, with 81% of children and 95% of adults not meeting the recommended amount.
Magnesium is another common deficiency that plays particular relevance to high-performance individuals, as it is involved in muscle and nerve function, electrolyte balance, and the creation of ATP. ATP is the body's main energy currency and can be harnessed to do work, such as exercise or respiration. Low magnesium levels result in muscle fatigue, impaired exercise performance, and amplified oxidative stress.
Like magnesium, low potassium levels can reduce one’s energy and endurance capabilities. The micronutrient works alongside magnesium and involves muscle and nerve contractions and blood pressure regulation. Although potassium is prevalent in many foods, it can also be lost easily through urination and sweat. Those who reside in warm climates or regularly engage in strenuous, high-capacity exercise are at particular risk of not achieving appropriate potassium levels. Even a moderate reduction can have effects on blood pressure and salt sensitivity.
Lastly, vitamin E is another common deficiency in the United States. Vitamin E contains antioxidant properties that make it essential for athletes looking to improve aerobic capacity. In addition, vitamin E is implicated in ensuring optimal immune system functioning and blood viscosity, two factors relevant to one’s ability to train and perform.
With that said, what is being done to correct these deficiencies so many face? One strategy has been to enrich and fortify common foods. Enrichment entails the addition of micronutrients to processed foods that lose these nutrients during development. On the other hand, fortification is the addition of nutrients to food that naturally doesn’t contain these compounds to prevent or correct a nutrition deficiency. These techniques are often used to add folate, niacin, riboflavin, thiamin, vitamin A, vitamin D, and iron to food. For example, vitamins A and D are often added to defatted milk to reproduce the content of whole milk, which naturally contains those vitamins.
Another way to tackle micronutrient deficiency has been to engineer existing crops into more nutrient-dense ones genetically. One example is the pearl millet, a staple crop in India that was reinvented in 2012 by HarvestPlus. This new crop, known as Dhanashakti, was bred with more potent iron levels in response to the millions of Indian children who were iron deficient. The crop was marketed specifically toward farmers who rely on pearl millet as a staple meal. As a result, Dhanashakti consumers demonstrated improved physical and cognitive performance and were finally on their way to growing up with healthier bodies and brains.
Indeed, most micronutrients cannot be synthesized by the human body and must be obtained directly from food consumption. Therefore, aside from genetically modified foods, the best thing is to eat a mindful diet incorporating a wide variety of healthy, minimally processed foods already on the market.
Dietary sources of calcium include seafood such as sardines or salmon, leafy greens, tofu, beans and lentils, seeds, and dried fruit. In addition to a good dose of sunshine, vitamin D can also be consumed through foods such as oily fish like salmon, sardines, herring, and mackerel. It is also found in mushrooms, egg yolks, red meat, and liver. Magnesium-rich foods include dark chocolate, avocados, legumes, whole grains, almonds, cashews, and Brazil nuts. Potassium can be found in more than just bananas; other options are sweet potatoes, spinach, watermelon, white and black beans, beets, and coconut water. Lastly, sources of vitamin E include sunflower seeds, mango, peanuts, rainbow trout, red sweet pepper, and oils derived from sunflower, almond, and hazelnut.
Undernutrition is slowly but surely being addressed with innovations across food distribution, genetically engineered crops, and food enrichment and fortification. Yet, larger-scale interventions are needed, including a systemic override to how food is produced and sold. As an overview, the world’s farmers produce enough food combined to feed over one and a half times the global population, amounting to 10 billion people. So how is it that despite this enormous excess, nutrient deficiencies still exist, affecting the health outcomes of countless individuals across the globe?
Across social, economic, and medical spheres, the global burden of malnutrition is serious and long-lasting for individuals, families, communities, and countries. For those of us who are fortunate enough to access and purchase food easily, simply knowing nutrition, specifically, the role micronutrients play in our bodies, is the first step to improving our health and quality of life. This knowledge can help align and advocate for policies that move nutrition forward on a global scale.