By Dr. Mercola

If you eat a balanced, whole-food diet like the one described in my nutrition plan, you’re probably getting adequate amounts of the vitamins and minerals your body needs to function.

If not (and this applies to the majority of the U.S. population), there’s a good chance you may be lacking important nutrients.

Even if you do eat well, how and where your food was grown can also influence your nutritional intake. Soil quality, storage time, and processing can significantly influence the levels of certain nutrients in your food.

Your age and certain health conditions (digestive issues and others) can also impact your body’s ability to absorb the nutrients in your food.

Unfortunately, in many cases nutrient deficiencies can be difficult to assess, and you may not develop symptoms until the deficiency has become quite pronounced.

Below, I will review 11 of the most common nutrient deficiencies,¹ and how to address them. Eating real food is usually your best bet, but sometimes supplementation may be advisable, especially if you’re showing signs of deficiency.

#1: Vitamin D

Vitamin D deficiency is prevalent in people of all ages, especially in those who choose to use topical sun screens (which blocks vitamin D production) or limit their outdoor activities.

Researchers estimate that 50 percent of the general population is at risk of vitamin D deficiency and insufficiency, and this percentage rises in higher-risk populations such as the elderly and those with darker skin.

Signs indicating you may have a vitamin D deficiency include being over the age of 50, having darker skin, obesity, achy bones, feeling blue, head sweating, and poor immune function.

Your best bet is to get your vitamin D level tested twice a year. Based on the evaluation of healthy populations that get plenty of natural sun exposure, the optimal range for general health appears to be somewhere between 50 and 70 ng/ml.

As for how to optimize your vitamin D levels, I firmly believe that sensible sun exposure is the best way, although vitamin D-rich foods and D3 supplements may also be necessary if you cannot get adequate sun exposure year-round.

How to Optimize Your Vitamin D

To optimize your levels, you need to expose large portions of your skin, such as your back, chest, legs, and arms, to sensible sun exposure. And, contrary to popular belief, the best time to be in the sun for vitamin D production is actually as near to solar noon as possible.

During this time you need the shortest exposure time to produce vitamin D because UVB rays are most intense at this time. Plus, when the sun goes down toward the horizon, the UVB is filtered out much more than the dangerous UVA.

Just be cautious about the length of your exposure. You only need enough exposure to have your skin turn the lightest shade darker. Once you reach this point your body will not make any additional vitamin D due to its self-regulating mechanism. Any additional exposure will only cause harm and damage to your skin.

Avoiding processed foods is another important consideration, as they tend to be loaded with the herbicide glyphosate (used on most conventional and genetically engineered food crops), and glyphosate has been shown to interfere with enzymes responsible for activating vitamin D in your liver and kidneys.

#2: Omega-3 Fats

Low concentrations of the omega-3 fats EPA and DHA² are associated with an increased risk of death from all causes, and omega-3 deficiency has been revealed as the sixth biggest killer of Americans.

Most Americans eat too many inflammatory omega-6 fats (think processed vegetable oils) and too few anti-inflammatory omega-3s, which sets the stage for a number of health problems, including cardiovascular disease, cancer, depression, Alzheimer’s, rheumatoid arthritis, and diabetes, just to name a few.

Telltale signs that your omega-3 to omega-6 ratio may be out of balance include dry, flaky skin, alligator skin, or “chicken skin” on backs of arms; dandruff or dry hair; soft brittle nails; fatigue; menstrual cramps, and poor attention span.

The ideal ratio of omega-3 to omega-6 fats is about 1:1, but the typical Western diet is between 1:20 and 1:50, so in addition to upping your omega-3 intake, you also need to reduce the amount of omega-6 in your diet, which means cutting down on processed and fried foods.

Sardines are one of the most concentrated sources of omega-3 fats,³ with one serving containing more than 50 percent of your recommended daily value. They also contain other nutrients that many are deficient in, such as vitamin B12, calcium, and choline.

If you decide to take omega-3s in supplement form, I believe krill oil is superior to fish oil. The omega-3 in krill is attached to phospholipids that increase its absorption, which means you need less of it.

Krill oil also contains almost 50 times more astaxanthin, a potent antioxidant, than fish oil, which prevents the highly perishable omega-3 fats from oxidizing before you are able to integrate them into your cellular tissue.

#3: Vitamin K2

Vitamin K2 may be just as important as vitamin D for optimal health. It’s essential for bone strength, the health of arteries and blood vessels, and plays a role in other biological processes as well, including tissue renewal and cell growth, healthy pregnancy, and cancer prevention.

In the 2014 paper,⁴ “Vitamin K: An old vitamin in a new perspective,” vitamin D expert Dr. Michael Holick and co-authors review the history of vitamin K and its many benefits, including its significance for bone and cardiovascular health.

Vitamin K2 is an important adjunct to vitamin D, without which vitamin D cannot work properly. K2’s biological action is also impaired by a lack of vitamin D, so you really need to consider these two nutrients together.

Vitamins D and K2 also work synergistically with magnesium and calcium, so this quartet should ideally be taken in combination.

Whereas vitamin K1 — which is the primary form of vitamin K responsible for blood clotting — can be found in green leafy vegetables, vitamin K2 is only present in fermented foods. It’s produced by certain bacteria during the fermentation process.

Examples of foods that are naturally high in vitamin K2 include natto (a fermented soy product) and fermented vegetables like sauerkraut. One of the best sources I’ve found is to ferment your own vegetables using a special starter culture designed with bacterial strains that produce vitamin K2.

Raw dairy products such as certain cheeses, raw butter, and kefir also contain high amounts. However, only grass-fed animals (not grain fed) will develop naturally high K2 levels.

Menaquinone-7 (MK-7) is the kind of vitamin K2 you want to look for in supplements, as this form is extracted from real food.

The other type of K2, known as MK-4, is only available in synthetic form, which has the additional drawback of having a very short biological half-life, necessitating taking it several times a day. Research⁵ has shown MK-7, specifically, helps prevent inflammation by inhibiting pro-inflammatory markers produced by white blood cells called monocytes.

#4: Magnesium

Magnesium is the fourth most abundant mineral in your body, yet an estimated 80 percent of Americans are deficient in it. Without sufficient amounts of magnesium your body simply cannot function at its best. Insufficient cellular magnesium levels set the stage for deterioration of proper metabolic function that typically snowballs into more significant health problems. Researchers have detected more than 3,750 magnesium-binding sites on human proteins,⁶ reflecting how important this mineral is to a great many biological processes.

For example, magnesium plays a role in your body’s detoxification processes and therefore is important for minimizing damage from environmental chemicals, heavy metals, and other toxins. Even glutathione, considered by many to be your body’s most powerful antioxidant, requires magnesium in order to be produced.

Magnesium also plays roles in preventing migraine headaches, cardiovascular disease (including high blood pressure, heart attacks, and strokes), sudden cardiac death, and even reduces death from all causes.

Low magnesium levels are also consistently found in those with elevated insulin,^7,8,9 and research¹⁰ suggests that magnesium intake may help reduce your risk of developing diabetes if you’re at high risk. The mechanism by which magnesium controls glucose and insulin homeostasis appears to involve two genes responsible for magnesium homeostasis.¹¹ Magnesium is also required to activate tyrosine kinase, an enzyme that functions as an “on” or “off” switch in many cellular functions and is required for the proper function of your insulin receptors.

How to Optimize Your Magnesium Levels

There’s no easily available commercial lab test that will give you an accurate reading of your magnesium status. However, in her book, The Magnesium Miracle, Dr. Carolyn Dean lists 100 factors that will help you decide whether or not you might be deficient. You can also follow the instructions in her blog post, “Gauging Magnesium Deficiency Symptoms,”¹² which will give you a check list to go through every few weeks. This will help you gauge how much magnesium you need in order to take away your deficiency symptoms.

Most people can keep their magnesium levels in the therapeutic range without resorting to supplements by eating a varied diet, including plenty of dark-green leafy vegetables. Seaweed and green leafy vegetables like spinach and Swiss chard can be excellent sources of magnesium, as are some beans, nuts, and seeds, like pumpkin, sunflower, and sesame seeds. Avocados also contain magnesium. Juicing your vegetables is an excellent option to ensure you’re getting enough of them in your diet.

Unfortunately, most foods grown today are deficient in magnesium (and other minerals). Glyphosate again plays a role, as it acts as a chelator, effectively blocking the uptake and utilization of minerals in the plant. For this reason, I believe it might be prudent to consider a magnesium supplement. You can also improve your magnesium status by taking regular Epsom salt baths or foot baths. Epsom salt is a magnesium sulfate that can be absorbed into your body through your skin. Magnesium oil (from magnesium chloride) can also be used for topical application and absorption.

If you opt for a magnesium supplement, two of the best ones include magnesium glycinate and magnesium threonate. The former is a chelated form of magnesium that tends to provide the highest levels of absorption and bioavailability. This form is typically considered ideal for those who are trying to correct a deficiency. Magnesium threonate is a newer type of that appears promising, primarily due to its superior ability to penetrate the mitochondrial membrane.

#5: Vitamin B12

Vitamin B12 (cobalamin) is known as the energy vitamin. Your body requires it for a number of vital functions, including energy production, blood formation, DNA synthesis, and myelin formation. The two ways you become deficient are through a lack of vitamin B12 in your diet, or through your inability to absorb it from the food you eat.

About one in four American adults are deficient in this important nutrient, and nearly half the population has suboptimal blood levels. Warning signs of B12 deficiency include “mental fog,” memory problems, mood swings, apathy, fatigue, muscle weakness, and tingling in the extremities. Unfortunately, B12 deficiency may not present itself for a number of years, so by the time you notice symptoms, you may be quite deficient.

Vitamin B12 is present in natural form only in animal sources of food, which is one of the reasons I advise against a no-animal-food vegan diet. B12-rich foods include beef and beef liver (grass-fed beef is highly preferable to the grain-fed variety), lamb, snapper, venison, salmon, shrimp, scallops, organic-pastured poultry, and eggs. When it comes to supplementation, your best alternatives include injectable B12 and sublingual drops or spray. Most oral supplements tend to be ineffective, as vitamin B12 is poorly absorbed.

#6: Vitamin E

Vitamin E is particularly important for your brain health, but it also helps support normal cholesterol levels, and protect against free radical damage and the normal effects of aging. Recent animal research warns that vitamin E deficiency may actually cause brain damage, while studies have also found that supplementation with it may help delay the loss of cognitive function in people with Alzheimer’s disease. According to lead author Maret Traber:¹³

“This research showed that vitamin E is needed to prevent a dramatic loss of a critically important molecule in the brain and helps explain why vitamin E is needed for brain health. Human brains are very enriched in DHA, but they can’t make it. They get it from the liver.

The particular molecules that help carry it there are these lyso PLs, and the amount of those compounds is being greatly reduced when vitamin E intake is insufficient. This sets the stage for cellular membrane damage and neuronal death. There’s increasingly clear evidence that vitamin E is associated with brain protection, and now we’re starting to better understand some of the underlying mechanisms.”

Important Pointers for Optimizing Your Vitamin E

The term “vitamin E” refers to a family of at least eight fat-soluble antioxidant compounds, divided into two main categories: tocopherols (which are considered the “true” vitamin E) and tocotrienols — each of which has subfamilies of four different forms. Ideally, vitamin E should be consumed in the broader family of mixed natural tocopherols and tocotrienols, (also referred to as full-spectrum vitamin E) to get the maximum benefits.

The vitamin E most often referred to and sold in most stores is a synthetic form of the vitamin, which really should NOT be used if you want to reap any of its health benefits. You can tell what you’re buying by carefully reading the label.

• Natural vitamin E is always listed as the “d-” form (d-alpha-tocopherol, d-beta-tocopherol, etc.)
• Synthetic vitamin E is listed as “dl-” forms

The best way to ensure that your body is getting the full spectrum of vitamin E, in a form your body can beneficially use, is to make smart dietary choices. Good dietary sources of vitamin E include nuts, such as hazelnuts, almonds, walnuts, and pecans; seeds such as sunflower seeds; olive oil; legumes; and green vegetables, such as spinach and broccoli.

#7: Vitamin A

Vitamin A is an essential fat-soluble vitamin that is important for maintaining healthy skin, teeth, bones, cell membranes, and vision. Vitamin A, like vitamin D, is also essential for your immune system. It’s a precursor to active hormones that regulate the expression of your genes, and vitamin A and D work in tandem. For example, there is evidence that without vitamin D, vitamin A can be ineffective or even toxic. But if you’re deficient in vitamin A, vitamin D cannot function properly either, so a balance of these two vitamins is essential.

Unfortunately, we do not yet know the optimal ratios between these two vitamins, which is why it’s best to get them from food and sun exposure, rather than relying on supplements. It’s also important to understand the difference between retinol and beta-carotene.¹⁴

Both are important forms of vitamin A, but it can be very difficult to get sufficient amounts of vitamin A from beta-carotene alone. Unless your intestinal health is top notch, and you eat your veggies with healthy fat, getting your vitamin A in the form of retinol from organic animal products is your best bet, and here’s why:

• Retinol is preformed vitamin A, found in animal products such as grass-fed meat and poultry, liver, fish, and raw organic dairy products like butter. This is the form of vitamin A your body can actually use.
• Beta-carotene is pre-vitamin A, found in plant foods like fruits and vegetables. In order for your body to actually use beta-carotene, it must first convert it into retinol, and to do this, you need to have a well-functioning digestive tract and sufficient bile produced by your gallbladder. Specific enzymes are also needed to break down the carotene for the conversion into retinol to occur.

Most people have poor gut health, which makes beta-carotene a poor alternative as a primary source of vitamin A. Also, to optimize the usable amount of vitamin A from your vegetables, you need to eat them with a bit of healthy fat, since bile is produced to help break down fat in your diet.

Vitamin A production is tightly controlled in your body, the source (substrate) being carotenoids from vegetables in your intestine. Your body uses these carotenoid substrates to make exactly the right amount of retinol. When you take vitamin A as retinol directly, you intervene in this closed system and bypass the controls. Ideally, you want to provide all the vitamin A and vitamin D substrate your body would have obtained in a natural state, so your body can regulate both systems naturally. This is best done by eating colorful vegetables and by exposing your skin to sun every day.

#8: Iodine

Iodine is an important nutrient found in every organ and tissue, and many are deficient in this nutrient. Worldwide, it’s thought that up to 40 percent of the population is at risk of iodine deficiency. Along with being essential for healthy thyroid function and efficient metabolism, there is increasing evidence that low iodine is related to numerous diseases, including cancer.  Iodine deficiency, or insufficiency, in any of these tissues will lead to dysfunction of that tissue. Hence the following symptoms could provide clues that you’re not getting enough iodine in your diet. For example, iodine deficiency in:

• Salivary glands = inability to produce saliva, producing dry mouth
• Skin = dry skin, and lack of sweating. Three to four weeks of iodine supplementation will typically reverse this symptom, allowing your body to sweat normally again
• Brain = reduced alertness and lowered IQ
• Muscles = nodules, scar tissue, pain, fibrosis, and fibromyalgia

There are potentially serious risks to taking too much iodine, however, which is why I generally do not advise taking large doses of iodine supplements like Lugol’s or Iodora long term. Your thyroid only transports iodine in its ionized form (i.e. iodide).  As an alternative, toxin-free sea vegetables and spirulina are likely the ideal natural sources from which to obtain your iodine.

Raw milk and eggs contain iodine, as well. At the same time, you’ll want to avoid all sources of bromine as much as possible, as this appears to play a large role in the rising levels of iodine deficiency.

#9: Calcium

Calcium is one of several nutrients required for strong, healthy bones. However, it’s important to not overdo it on calcium supplements. Calcium needs to be balanced with vitamin D, K2, and magnesium, or else it can do more harm than good. Lack of balance between these nutrients is why calcium supplements have become associated with increased risk of heart attack and stroke.

For example, if you have too much calcium and not enough magnesium, your muscles will tend to go into spasm, and this has consequences for your heart in particular. Excessive amounts of calcium without enough magnesium can lead to a heart attack and sudden death. You also need vitamin K2 to optimize calcium’s benefit. The biological role of vitamin K2 is to remove calcium from areas where it shouldn’t be (such as in your arteries and soft tissues), and shuttle it into the appropriate areas (such as your bones and teeth).

One of the best ways to achieve healthy bones is by consuming a diet rich in fresh, raw whole foods that maximize natural minerals so that your body has the raw materials it needs to do what it was designed to do. It’s more likely your body can use calcium correctly if it’s plant-derived calcium. Good sources include raw milk from pasture-raised cows (who eat the plants), leafy green vegetables, the pith of citrus fruits, carob, and wheatgrass, to name a few.

You also need sources of silica and magnesium, which some researchers say is actually enzymatically “transmuted” by your body into the kind of calcium your bones can use. Good sources of silica are cucumbers, bell peppers, tomatoes, and a number of herbs including horsetail, nettles, oat straw, alfalfa, and raw cacao, which is also extremely rich in highly bioavailable magnesium.

#10: Iron

Iron is essential for human life, as it is a key part of various proteins and enzymes, involved in the transport of oxygen and the regulation of cell growth and differentiation, among many other uses. One of the most important roles of iron is to provide hemoglobin (the protein in red blood cells), a mechanism through which it can bind to oxygen and carry it throughout your tissues, as without proper oxygenation, your cells quickly start dying.

If you have too little iron, you may experience fatigue, decreased immunity, or iron-deficiency anemia, which can be serious if left untreated. This is common in children and premenopausal women.

But, while iron deficiency affects more than a quarter of the global population, it’s equally hazardous to have too much iron, and elevated levels are just as common, or perhaps even more so than iron deficiency, thanks to a hereditary disease known as hemochromatosis, one of the most prevalent genetic diseases in the United States. While I was seeing patients, I regularly screened my patients for ferritin, and noticed nearly one-fourth of them had elevated levels.

If you have more iron than what your body needs to satisfy your hemoglobin requirement (for cell oxygenation), the rest becomes a surplus. And since your body has a limited capacity to excrete iron, it can build up in your body, with potentially lethal consequences. Iron is a very potent oxidant stressor.

The oxidation caused by too much iron causes dangerous free radicals to form, which can cause significant damage in your cells and increase your risk of heart disease by damaging the inner lining of your blood vessels. It can also damage your DNA and promote diseases like cancer.

Ferritin Test — An Important Preventive Health Screen as Too Much Iron Is as Dangerous as Too Low

Fortunately, checking your iron levels is easy and can be done with a simple blood test called a serum ferritin test. I believe this is one of the most important tests that everyone should have done on a regular basis as part of a preventive, proactive health screen. The test measures the carrier molecule of iron, a protein found inside cells called ferritin, which stores the iron. If your ferritin levels are low, it means your iron levels are also low.

The healthy range of serum ferritin lies between 20 and 80 ng/ml. Below 20 is a strong indicator that you are iron deficient, and above 80 suggests you have an iron surplus. The ideal range is between 40 to 60 ng/ml.

This test saved my dad’s life some two decades ago when I discovered he had a ferritin level close to 1,000. It was because he has beta-thalassemia. With regular phlebotomies, his iron levels normalized, but the high iron levels damaged his pancreatic islet cells and now he has what is called “bronze” diabetes that requires the use of insulin. I inherited beta-thalassemia from him so I’m quite familiar with this issue.

I keep my iron levels normal by removing about a pint of blood a year, extracted over a few dozen deposits. Considering the dangers of elevated iron levels, I strongly encourage you to be screened annually for this, as it is so much easier to prevent iron overload than it is to treat it.

#11: Choline

Choline¹⁵ is a B vitamin known for its role in brain development. It’s a precursor to the neurotransmitter acetylcholine, which plays a role in both muscle control and memory. Choline is also important for the health of your cell membranes, and has anti-inflammatory properties. An estimated 90 percent of the US population may be deficient in choline.¹⁶ Some of the symptoms associated with low levels include memory problems, lethargy, and persistent brain fog.

Your body can only synthesize small amounts of this nutrient, so you need to get it from your diet. Animal foods like organic pastured eggs and grass-fed meat are some of the best sources of choline, so if you’re a vegan or vegetarian who does not consume any animal foods, you may be at particular risk of deficiency. Other good sources of choline¹⁷ include beef liver, wheat germ, Brussel sprouts, broccoli, wild-caught salmon, and raw milk.

Tips to Supercharge Your Diet with Nutrients

As much as possible, I recommend getting the nutrients your body needs from whole foods. This means minimizing processed foods as much as possible and instead focusing on healthy fats, fresh produce, grass-fed meats and pastured poultry, raw dairy products, organic free-range eggs, nuts, and seeds, and, if you’re healthy, moderate amounts of fruit. That being said, there are a few tricks to get copious amounts of nutrients with little effort. You’ll still need to eat a variety of foods to get the wide range of nutrients your body needs, but the tips that follow will give you an excellent start:

• Homemade Bone Broth: Bone broth contains high amounts of calcium, magnesium, and other nutrients.
• Sprouts: Sprouts can contain up to 100 times more enzymes than raw fruits and vegetables, allowing your body to extract more vitamins, minerals, amino acids, and essential fats from the foods you eat.
• Juicing: Juicing not only helps you to consume more nutrient-rich veggies, it also helps you absorb the nutrients they contain. Juicing will help to “pre-digest” the veggies for you, so you will receive most of the nutrition, rather than having it go down the toilet.
• Fermented Foods: Fermented foods support the beneficial bacteria in your gut, which helps with mineral absorption and plays a role in producing nutrients such as B vitamins and vitamin K2.