Many people take a multivitamin to “be on the safe side” because they hear that the soil our food is grown in is no longer nutrient-dense or worry that their diet isn’t as healthy or diverse as it should be. The reality is that for most people, if your diet is varied and filled with a rainbow of fruits and vegetables, and you are healthy and absorbing nutrients well from your gastrointestinal tract, you probably don’t need the extra vitamins and minerals. But, some vitamin deficiencies are more common than you might think. Knowing the signs and symptoms of each and understanding simple ways to reverse these common nutrient deficiencies can go a long way.
According to the CDC , nearly 10 percent of people in the US have some nutrient or vitamin deficiency. And while the prevalence of each deficiency can vary by race, gender, and age, a common cause is really the standard American diet. Over time, as we’ve become more and more accustomed to eating processed foods high in sugar and saturated fats and low in fruits and vegetables, our bodies have stopped getting the doses of key nutrients that keep our body functioning optimally. Everything from feeling tired all the time to more serious health problems like kidney disease could be a result of a vitamin deficiency.
While a healthy diet may help you escape these common vitamin deficiencies, it doesn’t always guarantee that you’re getting everything you need. The reality is, our food is still highly processed, and even if you try to eat a well-balanced diet of natural, whole foods, it’s important to look out for the signs of a deficiency.
The best way to find out is to see your physician and have lab work performed to check your levels. At Parsley Health, we remove the guesswork by measuring many of these nutrients with in-depth laboratory tests. We then use this data to create a personalized nutrition plan for each member that brings their nutrient levels back into healthy ranges.
While each nutrient can have their own distinct set of symptoms, there are some that carry across almost all deficiencies. These include:
While this is not an exhaustive list, it’s also important not to pass off these symptoms as normal things to experience in everyday life. Instead, these symptoms are often clues that something deeper is going on in the body.
Here’s a look at the most common nutrient deficiencies we see in our members at Parsley Health, what a deficiency means for your overall health, and how you can address them.
Vitamin D gets the top spot on this list because almost every single member we see at Parsley Health is deficient in this essential vitamin. In one study of over 12,000 people, 72 percent were either Vitamin D deficient or insufficient, and these low levels of vitamin D were associated with high blood pressure, high BMI, and high cholesterol. Understanding what a vitamin D deficiency is, and what parts of your lifestyle are contributing, can help you resolve symptoms.
Some symptoms unique to vitamin D deficiency include:
While it’s true that we can get Vitamin D from the sun, most of us wear clothing that covers most of our bodies, use sunscreen, and spend the majority of our time indoors. Since sunlight on exposed skin is the primary way our bodies produce vitamin D, we simply don’t get enough to support our needs.
You’d think the answer would be straightforward, but it’s most definitely not. In 2011 the Endocrine Society issued a report recommending a vitamin D level of 30ng/mL, and because of inconsistencies with testing, suggested aiming for a level of 40-60ng/mL. But then some top doctors in the field said the minimal level should be decreased to 12.5ng/mL because only 6% of Americans have levels below that. In other words, they suggested we just lower the bar for what is considered deficient, and then we won’t have so many people low in vitamin D.
Some of the studies of vitamin D and risk for various cancers, cardiovascular disease, certain autoimmune diseases, falls and depression suggest that you need a level somewhere between 40-60ng/mL . At Parsley Health we aim for levels slightly above that, 50-70ng/mL which is also well below any risk for vitamin D toxicity. We also have our own Vitamin D optimized for maximum absorption .
Magnesium comes next because people are frequently deficient in it, in fact, 50 percent of Americans don’t reach the Estimated Average Requirement (EAR) for magnesium. Not only is magnesium deficiency common, but its value in health is often underappreciated. Magnesium plays a role in everything from your sleep to digestion and mental health, and even subclinical magnesium deficiency increases your risk of cardiovascular disease.
Some of the most common symptoms of magnesium deficiency include:
With less magnesium from our soil, which have become depleted of nutrients, and chemical processing taking nutrients out of our food supply, it’s becoming harder and harder to reach recommended magnesium levels from your diet alone. Grains, for example, a good source of magnesium, lose most of their magnesium content when they are refined. Medications can also impact magnesium levels: antacids decrease absorption and diuretics increase urinary excretion.
Magnesium’s most crucial role is in helping with brain, heart, and muscle function, but it’s also involved in the synthesis of DNA, RNA, and proteins, and is a critical factor in at least 600-800 enzymatic reactions. According to the National Institute of Health , recommended daily allowances range from 400-420 mg for adult men and 310-320 mg for adult women.
If magnesium is underappreciated, iodine is downright ignored. Ever since iodine was added to table salt, people in developed countries have stopped giving this mineral its due attention. But globally, iodine deficiency is extremely prevalent, with approximately 2 billion people suffering worldwide.
Iodine is used by the thyroid , stomach lining, and mammary glands to produce hormones that are essential for so many functions in your body . But as important as it is, it’s not naturally made by the body, meaning you need to get all necessary iodine from your diet—which many struggle with. Foods like seaweed salad, a sprinkle of dulse on your greens, or some kombu in your soup can be good sources of this element.
Iodine is one of those Goldilocks nutrients—you have to be careful you don’t get too much or too little. If you are severely deficient you could develop hypothyroidism, but even modest deficiencies may be problematic.
Although iodine deficiency is much less common in developed countries, it is still an issue, with about 10% of the population in the Americas and 52% of Europeans deficient . In the US, 15% of women of reproductive age are deficient. What qualifies as adequate is questionable, as the US RDA is 150mcg/day, while in Japan the typical intake is 1000-3000mcg/day.
Vitamin B12 plays a role in everything from making DNA to regulating brain function, but like iodine, it’s not made in the body, making deficiencies common. Vitamin B12 deficiency affects up to 15 percent of people , and without enough vitamin B12, everything from fatigue and weight loss to loss of appetite and constipation become common.
Vitamin B12 is abundant in animal products but practically non-existent in plant foods. That’s why we expect our vegan members to have low levels of this nutrient and need to take a supplement. However, what’s surprising is that many people who eat animal protein on a daily basis are also low in vitamin B12.
For those who don’t follow a vegan diet, common causes of this deficiency include:
Low stomach acidity: Stomach acid is needed to separate B12 from the food protein it is attached to when swallowed. Of course, acid-blocking medications decrease stomach acidity, and it often decreases simply in the course of aging.
Pernicious anemia: This is an autoimmune disease that interferes with the absorption of vitamin B12.
Small intestinal bacterial overgrowth (SIBO ): The bugs that mistakenly take up residence in the upper part of the small intestines in SIBO consume some of the B12 , so less reaches the lower part of the small intestines (ileum) where B12 gets absorbed into the bloodstream.
Metformin: This is the most common medication used to treat type 2 diabetes and can interfere with B12 absorption into the bloodstream.
MTHFR mutation : There are genetic variations in this gene that don’t affect B12 absorption but can affect its utilization in the cells.
MTHFR mutation : There are genetic variations in this gene that don’t affect B12 absorption but can affect its utilization in the cells.
As is true for most nutrients, assessing what is a sufficient level is not as straightforward as we’d like it to be. It is clear that people with blood levels of B12 < 150pg/mL are deficient, but plenty of people with levels higher than that still have inadequate stores of B12, so a level between 150-400 pg/mL is considered borderline.
Of all the nutrients in this list, iron is the most straightforward, but still so many Americans fail to reach the recommended amount. This commonly leads to iron deficiency anemia, a more serious condition in which your blood lacks enough healthy red blood cells. Anemia affects approximately 25 percent of people worldwide , and iron deficiency is said to be responsible for 50 percent of all anemias. So staying on top of iron levels is important to keeping your overall health in check.
Some symptoms unique to an iron deficiency include:
Iron comes from both plant and animal based foods. Plant sources of iron (called non-heme iron), such as leafy greens, legumes, nuts, and seeds, are not as easily absorbed as the iron that is present in animal sources (heme iron). So vegetarians and vegans are at higher risk for iron deficiency than omnivores. In addition, menstruating women, especially those with heavy periods, commonly have low iron stores.
A minimum level of ferritin, the major form of iron storage, is somewhere between 30-200ng/mL. Levels less than that often lead to iron deficiency anemia, with its associated symptoms, including fatigue, weakness and cold extremities. But even levels that aren’t low enough to cause anemia can still cause other problems, such as restless leg syndrome, hair loss, brittle or spooning of the nails, loss of sense of smell, and hypothyroidism .
Fortunately, it is easy to increase your iron levels either by eating red meat (ideally organic and grass fed) or taking an iron supplement. And if necessary, intravenous iron replacement is also an option.
Calcium is the most abundant mineral in the body and is well-known for its role in maintaining strong bones and teeth, but many people don’t get enough of this important mineral, especially as they age. One study of over 16,000 people found that 39 percent were getting less than the estimated average requirement for calcium. Calcium also helps to control muscles and nerves and regulates hormones. If you aren’t getting enough calcium in your diet, your body will start to steal it from its internal supply, your bones, raising your risk of developing osteoporosis.
Some of the most common symptoms of calcium deficiency include:
Two common causes of calcium deficiency are actually other deficiencies both listed in this article. Both vitamin D and magnesium deficiency impair the absorption of calcium by the body and promote hypocalcemia—illustrating the synergistic nature of vitamin and mineral functions in the body. Some additional common causes of calcium deficiency include a calcium-deficient diet, hormonal and digestive disorders, kidney dysfunction, and thyroid diseases.
The typical reference range for calcium levels in lab work is between 8.6 and 10.4 mg/dL. At Parsley Health, we like to see members’ calcium in a tighter range ideally between 9.2 and 10.1 mg/dL.
The safest and easiest way to prevent inadequate calcium levels is by incorporating more calcium-rich foods into your diet such as high quality, organic dairy products, salmon, sardines, beans, lentils, broccoli, turnip greens, sesame seeds, and kale. According to the National Institutes of Health, the daily recommended amount of calcium is 1,000 milligrams for people aged 19-50, while children, teens, and older adults need between 1,200 and 1,300 milligrams.
The nutrient deficiencies described above are the ones we most commonly see at Parsley Health, but of course, all vitamins and minerals are critical for optimal health, along with all the other nutrients scientists have identified or have yet to identify. Having these essential nutrients tested regularly is so important, but rarely done at a routine primary care visit. Ideally, rather than trying to guess your levels of these and other nutrients, your doctor should be testing these levels every year through routine blood work .
At Parsley Health, our doctors aim to have our members reach optimal levels of each of these nutrients, rather than just “normal range.” This means you’re getting more than just enough of the nutrient, allowing you to fully realize the benefits each one can bring—because even suboptimal levels can be associated with negative health effects like hypertension and thyroid disease . Always consult your physician before taking any new supplements to address any deficiencies you think you may be dealing with. As a Parsley Health member, you’ll work with your doctor and health coach to find the right combination of supplements , along with diet and lifestyle changes, to optimize your levels of each vitamin and mineral.
Dr. Lilli Link is a board-certified Internist and Functional Medicine Practitioner who graduated from medical school at the University of Chicago, and completed her residency at Columbia Presbyterian Medical Center in New York.
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