7 Incredibly Common Nutrient Deficiencies and How to Recognize Them

Many nutrients are absolutely essential for good health.
It is possible to get most of them from a balanced, real food-based diet.
However, the typical modern diet lacks several very important nutrients.
The typical modern diet lacks several very important nutrients. Photo credit: Shutterstock
This article lists seven nutrient deficiencies that are incredibly common.
1. Iron Deficiency
Iron is an essential mineral.
It is a main component of red blood cells, where it binds with hemoglobin and transports oxygen to cells.
There are actually two types of dietary iron:
- Heme iron: This type of iron is very well absorbed. It is only found in animal foods and red meat contains particularly high amounts.
- Non-heme iron: This type of iron is more common and is found in both animal and plant foods. It is not absorbed as easily as heme iron.
Iron deficiency is one of the most common nutrient deficiencies in the world, affecting more than 25 percent of people worldwide (1, 2).
This number rises to 47 percent in preschool children. Unless they're given iron-rich or iron-fortified foods, they are very likely to lack iron.
Thirty percent of menstruating women may be deficient as well, due to monthly blood loss. Up to 42 percent of young, pregnant women may also suffer from iron deficiency.
Additionally, vegetarians and vegans have an increased risk of deficiency. They consume only non-heme iron, which is not absorbed as well as heme iron (3, 4).
The most common consequence of iron deficiency is anemia. The quantity of red blood cells is decreased and the blood becomes less able to carry oxygen throughout the body.
Symptoms usually include tiredness, weakness, weakened immune system and impaired brain function (5, 6).
The Best Dietary Sources of Heme Iron Include (7):
- Red meat: Three ounces (85 g) of ground beef provides almost 30 percent of the RDI.
- Organ meat: One slice of liver (81 g) provides more than 50 percent of the RDI.
- Shellfish, such as clams, mussels and oysters: Three ounces (85 g) of cooked oysters provide roughly 50 percent of the RDI.
- Canned sardines: One 3.75 ounce can (106 g) provides 34 percent of the RDI.
The Best Dietary Sources of Non-Heme Iron Include (7):
- Beans: Half a cup of cooked kidney beans (3 ounces or 85 g) provides 33 percent of the RDI.
- Seeds, such as pumpkin, sesame and squash seeds: One ounce (28 g) of roasted pumpkin and squash seeds provide 11 percent of the RDI.
- Broccoli, kale and spinach: One ounce (28 g) of fresh kale provides 5.5 percent of the RDI.
However, you should never supplement with iron unless you truly need it. Too much iron can be very harmful.
Additionally, vitamin C can enhance the absorption of iron. Eating vitamin C-rich foods like oranges, kale and bell peppers along with iron-rich foods can help maximize iron absorption.
Bottom Line: Iron deficiency is very common, especially among young women, children and vegetarians. It may cause anemia, tiredness, weakness, weakened immune system and impaired brain function.
2. Iodine Deficiency
Iodine is an essential mineral for normal thyroid function and the production of thyroid hormones (8).
Thyroid hormones are involved in many processes in the body, such as growth, brain development and bone maintenance. They also regulate the metabolic rate.
Iodine deficiency is one of the most common nutrient deficiencies in the world. It affects nearly one-third of the world's population (9, 10, 11).
The most common symptom of iodine deficiency is an enlarged thyroid gland, also known as goiter. It may also cause an increase in heart rate, shortness of breath and weight gain (8).
Severe iodine deficiency may also cause serious adverse effects, especially in children. These include mental retardation and developmental abnormalities (8, 10).
There Are Several Good Dietary Sources of Iodine:
- Seaweed: Only 1 g of kelp contains 460–1000 percent of the RDI.
- Fish: 3 ounces (85 g) of baked cod provide 66 percent of the RDI.
- Dairy: One cup of plain yogurt provides about 50 percent of the RDI.
- Eggs: One large egg provides 16 percent of the RDI.
However, keep in mind that these amounts can vary greatly. Iodine is found mostly in the soil and the sea, so if the soil is iodine-poor then the food growing in it will be low in iodine as well.
Some countries have responded to iodine deficiency by adding it to salt, which has successfully reduced the severity of the problem (12).
Bottom Line: Iodine is one of the most common nutrient deficiencies in the world. It may cause enlargement of the thyroid gland. Severe iodine deficiency can cause mental retardation and developmental abnormalities in children.
3. Vitamin D Deficiency
Vitamin D is a fat-soluble vitamin that works like a steroid hormone in the body.
It travels through the bloodstream and into cells, telling them to turn genes on or off.
Almost every cell in the body has a receptor for vitamin D.
Vitamin D is produced out of cholesterol in the skin when it is exposed to sunlight. So people who live far from the equator are highly likely to be deficient, since they have less sun exposure (13, 14).
In the U.S., about 42 percent of people may be vitamin D deficient. This number rises to 74 percent in the elderly and 82 percent in people with dark skin, since their skin produces less vitamin D in response to sunlight (15, 16).
Vitamin D deficiency is not usually visible. The symptoms are subtle and may develop over years or decades (17, 18).
Adults who are deficient in vitamin D may experience muscle weakness, bone loss and increased risk of fractures. In children, it may cause growth delays and soft bones (rickets) (17, 20, 21).
Also, vitamin D deficiency may play a role in reduced immune function and an increased risk of cancer (22).
Unfortunately, very few foods contain significant amounts of this vitamin.
The Best Dietary Sources of Vitamin D Are (23):
- Cod liver oil: A single tablespoon contains 227 percent of the RDI.
- Fatty fish, such as salmon, mackerel, sardines or trout: A small, 3-ounce serving of cooked salmon (85 g) contains 75 percent of the RDI.
- Egg yolks: One large egg yolk contains 7 percent of the RDI.
People who are truly deficient in vitamin D may want to take a supplement or increase their sun exposure. It is very hard to get sufficient amounts through diet alone.
Bottom Line: Vitamin D deficiency is very common. Symptoms include muscle weakness, bone loss, increased risk of fractures and soft bones in children. It is very difficult to get sufficient amounts from diet alone.
4. Vitamin B12 Deficiency
Vitamin B12, also known as cobalamin, is a water-soluble vitamin.
It is essential for blood formation, as well as for brain and nerve function.
Every cell in your body needs B12 to function normally, but the body is unable to produce it. Therefore, we must get it from food or supplements.
Vitamin B12 is only found in animal foods (with the exception of nori seaweed and tempeh—see here). Therefore, people who do not eat animal products are at an increased risk of deficiency.
Studies have shown that vegetarians and vegans are highly likely to be deficient in vitamin B12. Some numbers go as high as 80–90 percent (24, 25).
More than 20 percent of elderly people may also be deficient in vitamin B12, since absorption decreases with age (26, 27, 28).
The absorption of vitamin B12 is more complex than the absorption of other vitamins, because it needs help from a protein known as intrinsic factor.
Some people are lacking in this protein and may therefore need B12 injections or higher doses of supplements.
One common symptom of vitamin B12 deficiency is megaloblastic anemia, which is a blood disorder that enlarges the red blood cells.
Other symptoms include impaired brain function and elevated homocysteine levels, which is a risk factor for several diseases (29, 30).
Dietary Sources of Vitamin B12 Include (7):
- Shellfish, especially clams and oysters: A 3-ounce (85 g) portion of cooked clams provides 1400 percent of the RDI.
- Organ meat: One 2-ounce slice (60 grams) of liver provides more than 1000 percent of the RDI.
- Meat: A small, 6-ounce beef steak (170 grams) provides 150 percent the RDI.
- Eggs: Each whole egg provides about 6 percent of the RDI.
- Milk products: One cup of whole milk provides about 18 percent of the RDI.
Large amounts of B12 are not considered harmful, because it is often poorly absorbed and excess amounts are expelled via urine.
Bottom Line: Vitamin B12 deficiency is very common, especially in vegetarians and the elderly. The most common symptoms include a blood disorder, impaired brain function and elevated homocysteine levels.
5. Calcium Deficiency
Calcium is essential for every cell. It mineralizes bone and teeth, especially during times of rapid growth. It is also very important for the maintenance of bone.
Additionally, calcium plays a role as a signaling molecule all over the body. Without it, our heart, muscles and nerves would not be able to function.
The calcium concentration in the blood is tightly regulated and any excess is stored in bones. If there is lack of calcium in the diet, calcium is released from the bones.
That is why the most common symptom of calcium deficiency is osteoporosis, characterized by softer and more fragile bones.
One survey found that in the U.S., less than 15 percent of teenage girls and less than 10 percent of women more than 50 met the recommended calcium intake (31).
In the same survey, less than 22 percent of young, teenage boys and men more than 50 met the recommended calcium intake from diet alone. Supplement use increased these numbers slightly, but the majority of people were still not getting enough calcium.
Symptoms of more severe dietary calcium deficiency include soft bones (rickets) in children and osteoporosis, especially in the elderly (32, 33).
Dietary Sources of Calcium Include (7):
- Boned fish: One can of sardines contains 44 percent of the RDI.
- Dairy products: One cup of milk contains 35 percent of the RDI.
- Dark green vegetables, such as kale, spinach, bok choy and broccoli: One ounce of fresh kale provides 5.6 percent of the RDI.
The effectiveness and safety of calcium supplements have been somewhat debated in the last few years.
Some studies have found an increased risk of heart disease in people taking calcium supplements, although other studies have found no effects (34, 35, 36).
Although it is best to get calcium from food rather than supplements, calcium supplements seem to benefit people who are not getting enough in their diet (37).
Bottom Line: Low calcium intake is very common, especially in young females and the elderly. The main symptom of calcium deficiency is an increased risk of osteoporosis in old age.
6. Vitamin A Deficiency
Vitamin A is an essential fat-soluble vitamin. It helps form and maintain healthy skin, teeth, bones and cell membranes.
Furthermore, it produces our eye pigments—which are necessary for vision (38).
There are two different types of dietary vitamin A:
- Preformed vitamin A: This type of vitamin A is found in animal products like meat, fish, poultry and dairy.
- Pro-vitamin A: This type of vitamin A is found in plant-based foods like fruits and vegetables. Beta-carotene, which the body turns into vitamin A, is the most common form.
More than 75 percent of people who eat a western diet are getting more than enough vitamin A and do not need to worry about deficiency (39).
However, vitamin A deficiency is very common in many developing countries. About 44–50 percent of preschool-aged children in certain regions have vitamin A deficiency. This number is around 30 percent in Indian women (40, 41).
Vitamin A deficiency can cause both temporary and permanent eye damage and may even lead to blindness. In fact, vitamin A deficiency is the world's leading cause of blindness.
Vitamin A deficiency can also suppress immune function and increase mortality, especially among children and pregnant or lactating women (40).
Dietary Sources of Preformed Vitamin A Include (7):
- Organ meat: One 2-ounce slice (60 g) of beef liver provides more than 800 percent the RDI.
- Fish liver oil: One tablespoon contains roughly 500 percent the RDI.
Dietary Sources of Beta-Carotene (Pro-Vitamin A) Include (7):
- Sweet potatoes: One medium, 6-ounce boiled sweet potato (170 g) contains 150 percent of the RDI.
- Carrots: One large carrot provides 75 percent of the RDI.
- Dark green leafy vegetables: One ounce (28 g) of fresh spinach provides 18 percent of the RDI.
While it is very important to consume enough vitamin A, it is generally not recommended to consume very large amounts of preformed vitamin A, as it may cause toxicity.
This does not apply to pro-vitamin A, such as beta-carotene. High intake may cause the skin to become slightly orange, but it is not dangerous.
Bottom Line: Vitamin A deficiency is very common in many developing countries. It may cause eye damage and lead to blindness, as well as suppress immune function and increase mortality among women and children.
7. Magnesium Deficiency
Magnesium is a key mineral in the body.
It is essential for bone and teeth structure and is also involved in more than 300 enzyme reactions (42).
Almost half of the U.S. population (48 percent) consumed less than the required amount of magnesium in 2005-2006 (43).
Low intake and blood levels of magnesium have been associated with several diseases, including type 2 diabetes, metabolic syndrome, heart disease and osteoporosis (43, 44).
Low levels of magnesium are particularly common among hospitalized patients. Some studies find that 9–65 percent of them are magnesium deficient (45, 46, 47).
This may be caused by disease, drug use, reduced digestive function or inadequate magnesium intake (48).
The main symptoms of severe magnesium deficiency include abnormal heart rhythm, muscle cramps, restless leg syndrome, fatigue and migraines (49, 50, 51)
More subtle, long-term symptoms that you may not notice include insulin resistance and high blood pressure.
Dietary Sources of Magnesium Include (7):
- Whole grains: One cup of oats (6 ounces or 170 g) contains 74 percent the RDI.
- Nuts: 20 almonds provide 17 percent of the RDI.
- Dark chocolate: 1 ounce (30 g) of dark chocolate (70–85 percent) provides 15 percent of the RDI.
- Leafy, green vegetables: 1 ounce (30 g) of raw spinach provides 6 percent of the RDI.
Bottom Line: Many people are eating very little magnesium and deficiency is common in Western countries. Low magnesium intake has been associated with many health conditions and diseases.
Take Home Message
It is possible to be deficient in almost every nutrient, but these seven are by far the most common.
Children, young women, the elderly and vegetarians seem to be at the highest risk of several deficiencies.
The best way to prevent a deficiency is to eat a balanced, real food-based diet that includes nutrient-dense foods (both plants and animals).
However, supplements can be necessary when it is impossible to get enough from the diet alone.
This article was reposted from our media associate Authority Nutrition.
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By Eric Tate and Christopher Emrich
Disasters stemming from hazards like floods, wildfires, and disease often garner attention because of their extreme conditions and heavy societal impacts. Although the nature of the damage may vary, major disasters are alike in that socially vulnerable populations often experience the worst repercussions. For example, we saw this following Hurricanes Katrina and Harvey, each of which generated widespread physical damage and outsized impacts to low-income and minority survivors.
Mapping Social Vulnerability
<p>Figure 1a is a typical map of social vulnerability across the United States at the census tract level based on the Social Vulnerability Index (SoVI) algorithm of <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/1540-6237.8402002" target="_blank"><em>Cutter et al.</em></a> [2003]. Spatial representation of the index depicts high social vulnerability regionally in the Southwest, upper Great Plains, eastern Oklahoma, southern Texas, and southern Appalachia, among other places. With such a map, users can focus attention on select places and identify population characteristics associated with elevated vulnerabilities.</p>Fig. 1. (a) Social vulnerability across the United States at the census tract scale is mapped here following the Social Vulnerability Index (SoVI). Red and pink hues indicate high social vulnerability. (b) This bivariate map depicts social vulnerability (blue hues) and annualized per capita hazard losses (pink hues) for U.S. counties from 2010 to 2019.
<p>Many current indexes in the United States and abroad are direct or conceptual offshoots of SoVI, which has been widely replicated [e.g., <a href="https://link.springer.com/article/10.1007/s13753-016-0090-9" target="_blank"><em>de Loyola Hummell et al.</em></a>, 2016]. The U.S. Centers for Disease Control and Prevention (CDC) <a href="https://www.atsdr.cdc.gov/placeandhealth/svi/index.html" target="_blank">has also developed</a> a commonly used social vulnerability index intended to help local officials identify communities that may need support before, during, and after disasters.</p><p>The first modeling and mapping efforts, starting around the mid-2000s, largely focused on describing spatial distributions of social vulnerability at varying geographic scales. Over time, research in this area came to emphasize spatial comparisons between social vulnerability and physical hazards [<a href="https://doi.org/10.1007/s11069-009-9376-1" target="_blank"><em>Wood et al.</em></a>, 2010], modeling population dynamics following disasters [<a href="https://link.springer.com/article/10.1007%2Fs11111-008-0072-y" target="_blank" rel="noopener noreferrer"><em>Myers et al.</em></a>, 2008], and quantifying the robustness of social vulnerability measures [<a href="https://doi.org/10.1007/s11069-012-0152-2" target="_blank" rel="noopener noreferrer"><em>Tate</em></a>, 2012].</p><p>More recent work is beginning to dissolve barriers between social vulnerability and environmental justice scholarship [<a href="https://doi.org/10.2105/AJPH.2018.304846" target="_blank" rel="noopener noreferrer"><em>Chakraborty et al.</em></a>, 2019], which has traditionally focused on root causes of exposure to pollution hazards. Another prominent new research direction involves deeper interrogation of social vulnerability drivers in specific hazard contexts and disaster phases (e.g., before, during, after). Such work has revealed that interactions among drivers are important, but existing case studies are ill suited to guiding development of new indicators [<a href="https://doi.org/10.1016/j.ijdrr.2015.09.013" target="_blank" rel="noopener noreferrer"><em>Rufat et al.</em></a>, 2015].</p><p>Advances in geostatistical analyses have enabled researchers to characterize interactions more accurately among social vulnerability and hazard outcomes. Figure 1b depicts social vulnerability and annualized per capita hazard losses for U.S. counties from 2010 to 2019, facilitating visualization of the spatial coincidence of pre‑event susceptibilities and hazard impacts. Places ranked high in both dimensions may be priority locations for management interventions. Further, such analysis provides invaluable comparisons between places as well as information summarizing state and regional conditions.</p><p>In Figure 2, we take the analysis of interactions a step further, dividing counties into two categories: those experiencing annual per capita losses above or below the national average from 2010 to 2019. The differences among individual race, ethnicity, and poverty variables between the two county groups are small. But expressing race together with poverty (poverty attenuated by race) produces quite different results: Counties with high hazard losses have higher percentages of both impoverished Black populations and impoverished white populations than counties with low hazard losses. These county differences are most pronounced for impoverished Black populations.</p>Fig. 2. Differences in population percentages between counties experiencing annual per capita losses above or below the national average from 2010 to 2019 for individual and compound social vulnerability indicators (race and poverty).
<p>Our current work focuses on social vulnerability to floods using geostatistical modeling and mapping. The research directions are twofold. The first is to develop hazard-specific indicators of social vulnerability to aid in mitigation planning [<a href="https://doi.org/10.1007/s11069-020-04470-2" target="_blank" rel="noopener noreferrer"><em>Tate et al.</em></a>, 2021]. Because natural hazards differ in their innate characteristics (e.g., rate of onset, spatial extent), causal processes (e.g., urbanization, meteorology), and programmatic responses by government, manifestations of social vulnerability vary across hazards.</p><p>The second is to assess the degree to which socially vulnerable populations benefit from the leading disaster recovery programs [<a href="https://doi.org/10.1080/17477891.2019.1675578" target="_blank" rel="noopener noreferrer"><em>Emrich et al.</em></a>, 2020], such as the Federal Emergency Management Agency's (FEMA) <a href="https://www.fema.gov/individual-disaster-assistance" target="_blank" rel="noopener noreferrer">Individual Assistance</a> program and the U.S. Department of Housing and Urban Development's Community Development Block Grant (CDBG) <a href="https://www.hudexchange.info/programs/cdbg-dr/" target="_blank" rel="noopener noreferrer">Disaster Recovery</a> program. Both research directions posit social vulnerability indicators as potential measures of social equity.</p>Social Vulnerability as a Measure of Equity
<p>Given their focus on social marginalization and economic barriers, social vulnerability indicators are attracting growing scientific interest as measures of inequity resulting from disasters. Indeed, social vulnerability and inequity are related concepts. Social vulnerability research explores the differential susceptibilities and capacities of disaster-affected populations, whereas social equity analyses tend to focus on population disparities in the allocation of resources for hazard mitigation and disaster recovery. Interventions with an equity focus emphasize full and equal resource access for all people with unmet disaster needs.</p><p>Yet newer studies of inequity in disaster programs have documented troubling disparities in income, race, and home ownership among those who <a href="https://eos.org/articles/equity-concerns-raised-in-federal-flood-property-buyouts" target="_blank">participate in flood buyout programs</a>, are <a href="https://www.eenews.net/stories/1063477407" target="_blank" rel="noopener noreferrer">eligible for postdisaster loans</a>, receive short-term recovery assistance [<a href="https://doi.org/10.1016/j.ijdrr.2020.102010" target="_blank" rel="noopener noreferrer"><em>Drakes et al.</em></a>, 2021], and have <a href="https://www.texastribune.org/2020/08/25/texas-natural-disasters--mental-health/" target="_blank" rel="noopener noreferrer">access to mental health services</a>. For example, a recent analysis of federal flood buyouts found racial privilege to be infused at multiple program stages and geographic scales, resulting in resources that disproportionately benefit whiter and more urban counties and neighborhoods [<a href="https://doi.org/10.1177/2378023120905439" target="_blank" rel="noopener noreferrer"><em>Elliott et al.</em></a>, 2020].</p><p>Investments in disaster risk reduction are largely prioritized on the basis of hazard modeling, historical impacts, and economic risk. Social equity, meanwhile, has been far less integrated into the considerations of public agencies for hazard and disaster management. But this situation may be beginning to shift. Following the adage of "what gets measured gets managed," social equity metrics are increasingly being inserted into disaster management.</p><p>At the national level, FEMA has <a href="https://www.fema.gov/news-release/20200220/fema-releases-affordability-framework-national-flood-insurance-program" target="_blank">developed options</a> to increase the affordability of flood insurance [Federal Emergency Management Agency, 2018]. At the subnational scale, Puerto Rico has integrated social vulnerability into its CDBG Mitigation Action Plan, expanding its considerations of risk beyond only economic factors. At the local level, Harris County, Texas, has begun using social vulnerability indicators alongside traditional measures of flood risk to introduce equity into the prioritization of flood mitigation projects [<a href="https://www.hcfcd.org/Portals/62/Resilience/Bond-Program/Prioritization-Framework/final_prioritization-framework-report_20190827.pdf?ver=2019-09-19-092535-743" target="_blank" rel="noopener noreferrer"><em>Harris County Flood Control District</em></a>, 2019].</p><p>Unfortunately, many existing measures of disaster equity fall short. They may be unidimensional, using single indicators such as income in places where underlying vulnerability processes suggest that a multidimensional measure like racialized poverty (Figure 2) would be more valid. And criteria presumed to be objective and neutral for determining resource allocation, such as economic loss and cost-benefit ratios, prioritize asset value over social equity. For example, following the <a href="http://www.cedar-rapids.org/discover_cedar_rapids/flood_of_2008/2008_flood_facts.php" target="_blank" rel="noopener noreferrer">2008 flooding</a> in Cedar Rapids, Iowa, cost-benefit criteria supported new flood protections for the city's central business district on the east side of the Cedar River but not for vulnerable populations and workforce housing on the west side.</p><p>Furthermore, many equity measures are aspatial or ahistorical, even though the roots of marginalization may lie in systemic and spatially explicit processes that originated long ago like redlining and urban renewal. More research is thus needed to understand which measures are most suitable for which social equity analyses.</p>Challenges for Disaster Equity Analysis
<p>Across studies that quantify, map, and analyze social vulnerability to natural hazards, modelers have faced recurrent measurement challenges, many of which also apply in measuring disaster equity (Table 1). The first is clearly establishing the purpose of an equity analysis by defining characteristics such as the end user and intended use, the type of hazard, and the disaster stage (i.e., mitigation, response, or recovery). Analyses using generalized indicators like the CDC Social Vulnerability Index may be appropriate for identifying broad areas of concern, whereas more detailed analyses are ideal for high-stakes decisions about budget allocations and project prioritization.</p>Wisconsin will end its controversial wolf hunt early after hunters and trappers killed almost 70 percent of the state's quota in the hunt's first 48 hours.
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