Top 12 Foods with Zinc

Find out the symptoms and consequences of zinc deficiency, plus the top 12 foods that contain zinc and can provide you with this essential nutrient for your senses, growth, and healing. 

Zinc is a trace mineral found throughout the body that is necessary for our immune system’s function, cell growth and division, wound healing, and our senses of taste and smell. Zinc is needed in over 300 enzyme functions in the body, and yet the body doesn’t store zinc as a reserve. Instead, zinc is used as needed to metabolize nutrients, and so we need to get a regular supply of it via our food or dietary supplement. For men this means 11 milligrams of zinc per day, and for women, it’s 8 milligrams unless they are pregnant or breastfeeding, when the requirement jumps up to 12 milligrams per day. This article will explore the symptoms and consequences of zinc deficiency, plus arm you with a list of the top 12 foods with zinc, so you’ll never have to go without this important nutrient.

Symptoms of Zinc Deficiency and Those at Risk

If you are a vegetarian or vegan, you might be more prone to zinc deficiency due to a lack of meat in your diet. Likewise those with digestive diseases such as Crohn’s disease, celiac disease, or ulcerative colitis may develop a deficiency due to poor absorption rates. Those with certain cancers, alcohol addiction, or diabetes are also at a higher risk. Breastfeeding and pregnant women, the elderly, as well as children and teens run the risk of becoming zinc deficient more easily. What follows next is a list of symptoms, so you can better recognize the signs of zinc deficiency.

  • Slowed growth
  • Poor immune functioning
  • Appetite loss
  • Hair loss
  • Impaired wound healing
  • Diarrhea
  • Unexplained weight loss
  • Compromised night vision
  • White spots on nails
  • A funny-tasting sensation
  • Lethargy
  • Fine tremors (unintentional muscle movements)

A moderate deficiency can be fixed with dietary changes. A severe deficiency may require zinc supplements and advice from a medical professional on how to best restore zinc levels.

The Top 12 Foods with Zinc

If you’re looking for foods high in zinc, look no further than the following list of top 12 zinc-rich foods.

The top 12 foods with zinc.

1. Legumes

Legumes include lentils, beans, and chickpeas, and are some of the best foods around for those who don’t eat meat to gain plant sources of protein and zinc. In 100 grams of lentils for example, you can get 12% of the daily recommended intake of zinc (for a man or pregnant/nursing woman).

Animal sources of zinc are better absorbed due to the fact that legumes also contain phytates, which can inhibit the absorption of zinc and other minerals. Regardless, legumes are an excellent source of fiber and protein that can be easily included in stews, salads, and soups—an easy and beneficial addition.

Bioavailability can also be increased with sprouting, fermenting, and soaking plant sources of zinc, which is great news for those seeking foods with zinc for vegan diets.

2. Meat

Meat is a strong source of zinc, especially red meat. Lamb, pork, bison, and beef are foods with high zinc and iron content, plus creatine and B vitamins. For zinc, raw ground beef contains 4.8 milligrams of zinc, 43% of a man’s RDI.

Though not everyone will want to eat large amounts of red meat due to its association with heart disease, it can still nevertheless be included moderately in a balanced diet to gain the positives without risking much in negative effects.

3. Seeds

Squash seeds, flaxseeds, sesame seeds, hemp seeds, and pumpkin seeds: all of these seeds help increase your zinc intake. They can be easily added to other foods like yogurts and salads, or enjoyed on their own as snacks in trail mixes or granola bars.

Some seeds contain more zinc than others. Hemp seeds in particular have 31% of a man’s RDI in just 3 tablespoons (30 grams) of seeds. That being said, sesame, squash, and pumpkin seeds each have significant amounts of zinc, as well as fiber, vitamins, minerals, and healthy fats. Including more seeds in your diet can help to lower blood pressure and reduce cholesterol, so they’re a fantastic resource for your health.

4. Shellfish

Shellfish like oysters and shrimp are low-calorie, healthy sources of zinc. Just six medium oysters can provide 32 milligrams of zinc, 290% of a man’s recommended daily intake. This category includes Alaskan crab, clams, scallops, mussels, and lobster.

It’s recommended that you cook shellfish thoroughly to avoid food poisoning, and also that you use a wet heat method of cooking like steaming, boiling, poaching, or braising instead of dry heat methods like grilling, broiling, sautéing, roasting, or baking, as those tend to reduce the zinc levels in shellfish.

5. Eggs

Eggs have about 5% of a man’s RDI per large whole egg, and they also bring 5 grams of healthy fats, 6 grams of protein, and vitamins and minerals. One of the foods with high zinc and selenium content, eggs also have an assortment of B vitamins and choline, which is important for many of the steps in our metabolism, and a nutrient that most of us do not get enough of from our diets.

6. Nuts

Cashews, almonds, peanuts (yes, we know technically they’re legumes but we’re eating them like nuts!), pine nuts, and more: all of these nuts can boost your zinc intake, as well as provide healthy fats, fiber, and a dazzling array of other vitamins and nutrients like iron, calcium, vitamin E, and folate.

Nuts are foods with zinc and magnesium, and among the nuts, your best source of zinc are cashews, with about 14% of a man’s RDI amount in a 1-ounce serving. Convenient, hearth healthy, and excellent for reducing the risk factors of diabetes, nuts have also been associated with greater longevity.

7. Certain Vegetables

Though vegetables and plant foods tend to be poorer sources of zinc than animal products, it’s nevertheless possible to get zinc from certain vegetables. For those who don’t eat meat, both sweet and regular potatoes have about 1 gram of zinc per large spud, 9% of a man’s daily recommended. Green veggies like green beans and kale contribute a small portion of zinc as well, about 3% of the RDI per 100 grams. While they may not contain a lot of zinc, greens like kale do contain chart-topping portions of vitamin K and vitamin A, and a vegetable-rich diet is associated with risk reduction for conditions like heart disease and cancer.

8. Dairy Products

Dairy products like milk and cheese have high amounts of particularly bioavailable zinc, meaning it’s more easily absorbed by your body. Just 100 grams of cheddar cheese has around 28% of a man’s RDI of zinc, and 1 cup of full-fat milk has about 9%. With calcium for bone health, vitamin D, and protein, dairy products are good sources of zinc, especially for any lacto-vegetarians.

9. Certain Fruits

Zinc-rich fruits include avocados, blackberries, pomegranate, raspberries, guava, cantaloupe, apricots, peaches, kiwifruit, and blueberries. With healthy fats in avocados and the anti-inflammatory and antioxidant properties of berries, though they don’t have very much zinc content compared to animal sources, these fruits are nevertheless more food sources that can help keep your body plentiful with zinc.

10. Whole Grains

Wheat, rice, oats, and quinoa each contain some zinc, though like the legumes listed above, they also contain phytates that can bind with zinc and inhibit its absorption. Whole grains contain more phytates than refined grains do, but they are still better for your health overall, as they also contain nutrients like B vitamins, selenium, magnesium, iron, and valuable fiber. Eating whole grains is associated with a reduced risk of obesity, type 2 diabetes, and heart disease, and so very much worth including in your diet for the other health benefits they bring.

11. Dark Chocolate

Among the foods with zinc and copper, dark chocolate has pretty fair amounts of zinc, about 30% of a man’s daily recommended intake with 3.3 milligrams of zinc per 100 grams. The only issue, of course, is that 100 grams of dark chocolate means 600 calories worth of food, so though dark chocolate has valuable nutrient content, it’s still a food that is best eaten in moderation, and not thought of as a main source of zinc.

12. Fortified Breakfast Cereals

Fortified breakfast cereals are a good source of zinc because they’re designed to make up the difference in specific vitamins and nutrients we’re often lacking in our diets. Great for growing children and adults, certain breakfast cereals will not only provide you with the benefits of zinc, but also with calcium, dietary fiber, and a cavalcade of vitamins.

From A to Zinc

Good sources of zinc like meat, nuts, seafood, dairy, and legumes are great to have as staples in your diet. The foods containing only marginal amounts of this essential mineral are still important too, as they round out your diet in a balanced fashion. Now you know that foods containing zinc are as diverse as they come, from just about every building block on the food pyramid. With their help, you could get regular amounts of zinc every day, and hardly notice the effort!

What You Need to Know About Vitamin D Deficiency

According to the latest research, far more people may have a vitamin D deficiency than previously believed. Read on to learn vitamin D deficiency symptoms, how much vitamin D you really need, and the best sources of vitamin D.

New data suggests that the benefits of vitamin D—the sunshine vitamin—go way beyond bone health. The latest research also indicates that far more people may have a vitamin D deficiency than previously believed, as it seems the threshold for optimal vitamin D levels was historically set too low! Read on to learn vitamin D deficiency symptoms, how much vitamin D you really need, and the best sources of vitamin D.

The Discovery of Vitamin D

The discovery of vitamin D stemmed from the medical study of a childhood borne disease called rickets. You might never have heard of rickets, because it’s quite rare now, but that hasn’t always been the case.

First described in an official medical work in 1650 by Francis Glisson, rickets spiked during the Industrial Revolution when the number of children suffering from the disease climbed as high as 60% in urban areas. Then, in 1822, a researcher named Sniadecki recognized that rickets was caused by inadequate exposure to sunlight. By the mid-1800s, medical professionals had adopted cod liver oil as a highly effective treatment for rickets, and in 1919, a pair of researchers identified vitamin D as the active ingredient responsible for cod liver oil’s curative effect.

Signs and Risks of Low Vitamin D

The classic vitamin D deficiency symptoms all relate to bone health, which makes sense because your body requires adequate vitamin D saturation to absorb calcium and phosphorus, the building blocks of strong bones. When your levels drop too low, your bones can become soft, brittle, or misshapen.

It now appears that vitamin D influences far more than just the health of your bones. Ongoing investigation shows that vitamin D could play a role in immune function and insulin regulation, meaning it may help to prevent certain chronic diseases and even cancer, according to an article written by Katherine Zeratsky, a registered dietician at the Mayo Clinic.

The latest findings also establish that many people have suboptimal vitamin D levels. Data from the Centers for Disease Control and Prevention (CDC) reveal that the percentage of white American adults with optimal vitamin D levels has declined from 60% in 1988-1994 to approximately 30% in 2001-2004. Since darker skin pigmentation increases your risk of deficiency, the numbers are even more dire for African Americans. During that same time, the percentage of adults with optimal vitamin D levels fell from approximately 10% to 5%.

Here’s how some risk factors contribute to a vitamin D deficiency as well as vitamin D deficiency causes:

  • Lifestyle: The less time you spend outdoors, the more likely it is that you’re not taking in enough vitamin D.
  • Age: As we age, our skin becomes less efficient at producing vitamin D, making us more susceptible to deficiencies.
  • Body weight: There’s a correlation between higher body fat percentages and lower vitamin D levels, so if you’re medically overweight or obese, you’re at greater risk of having low vitamin D.
  • Skin tone: Natural pigments called melanin determine how light or dark your skin looks. In basic terms, more melanin means darker skin. Because melanin slows down production of vitamin D, having dark skin also increases the chances you’ll be deficient.
  • Season: During the winter months, the sun is at too low an angle in the sky to generate much vitamin D production in your skin, even if you’re spending time outside. Your skin does store up vitamin D from summer sun exposure, but by late winter, deficiencies can set in, especially for people living at higher latitudes.

 

Learn about vitamin D deficiency.

A 2010 article on identifying and treating vitamin D deficiency notes that while it’s “well established that many people have vitamin D levels that are less than currently recommended for optimal health,” it doesn’t make sense to universally screen for the deficiency since the tests are quite expensive. As long as patients appear to have no evidence of a true deficiency, and instead seem likely to have developed an insufficiency, the authors recommend adjusting lifestyle factors to achieve optimal levels.

Vitamin D Insufficiency vs. Vitamin D Deficiency

Even when doctors do decide to test for a vitamin D deficiency, there are serious questions about what the cutoff should be to determine a deficiency or insufficiency. In an article on vitamin D insufficiency published in Mayo Clinic Proceedings, a peer-reviewed medical journal, Dr. Tom D. Thatcher and Dr. Bart L. Clarke argue: “Reliance on a single cutoff value to define vitamin D deficiency or insufficiency is problematic because of the wide individual variability of the functional effects of vitamin D and interaction with calcium intakes.”

Thatcher and Clarke conclude that the best, most prudent approach would be for at-risk individuals to increase their vitamin D intake.

If you’re concerned about a possible deficiency or insufficiency, you may want to asses whether you show any of the following signs of low vitamin D:

  • Blue mood: There’s a strong link between serotonin, the brain hormone associated with feelings of well-being and happiness, and sun exposure. A 2006 research study that enrolled 80 elderly patients found that those with the lowest levels of vitamin D were 11 times more likely to be depressed than those with more optimal levels.
  • Fatigue and tiredness: Even moderately low levels of vitamin D have been shown to increase fatigue and impair quality of life, according to this large observational study. Further research supports the connection between low levels of vitamin D and tiredness.
  • Bone pain and muscle weakness: Dr. Michael F. Holick, one of the preeminent experts in the field of vitamin D research, believes that many patients diagnosed with fibromyalgia may actually be vitamin D deficient. “Many of these symptoms are classic signs of vitamin D deficiency osteomalacia, which is different from the vitamin D deficiency that causes osteoporosis in adults,” Holick said. “What’s happening is that the vitamin D deficiency causes a defect in putting calcium into the collagen matrix into your skeleton. As a result, you have throbbing, aching bone pain.”
  • Head sweating: This one may sound strange, but it’s one of the classic signs of vitamin D deficiency! In fact, when the deficiency was more common in childhood and associated with serious health consequences like rickets, doctors used to routinely ask new mothers whether their infant’s head was sweating.
  • Frequent illnesses and infections: Vitamin D plays a crucial role in keeping your immune system functioning at peak capacity, so when your levels are low, you’re more susceptible to getting sick.
  • Slow wound healing: Several studies have found a connection between vitamin D and wound healing. In 2016, a team from the Wound Healing Research Group at the University of Alberta published findings indicating that vitamin D ramps up the production of compounds needed to form new skin as part of the wound-healing process.

Learn about vitamin D deficiency.

Lack of Vitamin D Can Lead to These 5 Illnesses

If the symptoms of vitamin D deficiency get overlooked for too long, more serious illnesses can develop. Scientists are still teasing out the connections between vitamin D and various conditions. So far, research demonstrates that vitamin D may play a role in the progression of dementia, prostate cancer, erectile dysfunction (ED), schizophrenia, and heart disease, among others. Studies also suggest a possible protective element against diabetes, high blood pressure, and multiple sclerosis, but more research needs to be conducted.

Dementia

The journal Neurology published a study in 2014 linking moderate and severe vitamin D deficiency in older adults with as much as a 50% increased risk of developing Alzheimer’s disease and other forms of dementia. The study enrolled over 1,600 participants, all of whom were at least 65 years of age and none of whom had dementia at the outset. The authors found that participants with low levels of vitamin D had a 53% increased risk of developing all-cause dementia, and those with severe deficiencies had a 125% increased risk!

They also found that participants with low vitamin D levels were approximately 70% more likely to develop Alzheimer’s disease in particular.

The researchers did note that their study was observational, meaning it did not establish a causal relationship between vitamin D deficiency and dementia. Their working theory at the time was that vitamin D might clear away plaques in the brain, the growth of which gives rise to memory loss and the other symptoms of dementia.

Prostate Cancer

A team of researchers from Northwestern University published findings in Clinical Cancer Research in 2014 on the relationship between low vitamin D levels and prostate cancer. After analyzing the vitamin D levels of 667 men between the ages of 40 and 79 who were undergoing prostate biopsies, the team found an especially clear link between low vitamin D and prostate cancer for African-American men.

When the disease was more progressed, they also found a connection to low vitamin D levels for white men. They believe various factors make it challenging to develop a clear rubric for using vitamin D levels as a biomarker for prostate cancer, but that it warrants further exploration. And, again, the findings were observational.

Erectile Dysfunction (ED)

The Journal of Sexual Medicine published original research on a possible link between vitamin D levels and ED. The authors assessed the severity of participants’ conditions using the International Index of Erectile Function (IIEF-5) and classified the root causes as arteriogenic, borderline, and non-arteriogenic.

Based on a fairly small study of 143 participants, the authors found that a significant portion of the participants had low levels of vitamin D, and that those with arteriogenic ED were far more likely to have deficiencies or insufficiencies.

Arteriogenic ED is caused by insufficient arterial blood supply. The study authors hypothesized that lack of vitamin D may impede the arteries’ ability to dilate, which would be in line with the stronger association between vitamin D deficiency and arteriogenic ED.

Schizophrenia

A meta-analysis of 19 observational studies on vitamin D deficiency and schizophrenia found that individuals with a lack of vitamin D can have as much as a 50% greater risk of a schizophrenia diagnosis compared to individuals with appropriate vitamin D levels.

They found that schizophrenia is more common at high latitudes and in cold climates, which correlates with known causes of vitamin D deficiency. They noted that randomized controlled trials would be necessary to determine whether increasing vitamin D levels could help to prevent schizophrenia. Unrelated studies also support a connection between vitamin D and mental health more broadly, making this an appealing area for further research.

Heart Disease

Two scientists from the Vascular Surgery Research Group at Imperial College in London published a literature review in an American Heart Association journal that concluded there is strong evidence to support “an independent association between vitamin D deficiency and various manifestations of degenerative cardiovascular disease.” Specifically, a lack of vitamin D appears to increase your chances of developing atherosclerosis, hypertension, diabetes, and stroke.

The authors did mention that at this time, it’s not clear whether increasing levels of vitamin D can help manage cardiovascular disease.

How Much Vitamin D Do You Need?

The way experts talk about how our bodies use vitamin D and how much vitamin D we need can be quite confusing. To properly evaluate how much vitamin D you need, it’s important to understand some basic facts about the vitamin and how your body takes it in.

There are two forms of vitamin D: vitamin D2 and vitamin D3. Vitamin D3, also called cholecalciferol, is the form your skin produces when exposed to UVB rays in sunlight. You can also get vitamin D3 from certain animal protein sources. Vitamin D2, also known as ergocalciferol, can be found in some plants. It’s also produced commercially for the irradiation of yeast and used for fortification and supplementation. Both vitamin D2 and D3 can be used for vitamin D supplementation.

Once you ingest them, your body breaks down both forms of vitamin D in the exact same way. There’s some evidence that your body breaks down vitamin D3 faster, but it appears that as long as you’re regularly getting enough, your body can use both vitamin D2 and D3 efficiently. Your liver converts both forms to 25-hydroxyvitamin D, or 25(OH)D, the compound that blood tests measure to determine vitamin D deficiency or insufficiency.

Determining a healthy vitamin D level can be challenging. Typically blood levels of 25(OH)D are measured in nanograms per milliliter, or ng/mL. In 2010, the Institute of Medicine declared that any level below 20 ng/mL was considered a vitamin deficiency that put you at risk for bone health problems. The following year, the Endocrine Society urged an even higher minimum of at least 30 ng/mL, with between 40 and 60 ng/mL identified as an optimal range.

As our understanding of the importance of vitamin D expands, and the threshold for what’s considered a deficiency continues to be adjusted, some experts propose that we treat between 50 and 70 ng/mL as the optimal range, and aim for blood levels that fall between those two points.

So, how much vitamin D do you need to take in to maintain optimal levels? Different organizations recommend different levels. Some experts believe that more evidence is needed to back recommendations for higher doses, while others believe taking lower amounts just isn’t enough. For adults, the minimum daily intake recommendations range from 600 IU (international units) to 5,000 IU and the upper limits from 4,000 IU to 10,000 IU.

Learn about vitamin D deficiency.

The argument in favor of the higher recommendations is supported by the data on the amounts of vitamin D generated in response to sun exposure. Thatcher and Clarke state that 20 minutes of summer sun exposure on bare skin produces the equivalent of 15,000 to 20,000 IU of vitamin D3.

If you do choose to take vitamin D supplements, it’s important not to exceed maximum recommended doses. Vitamin D is fat-soluble, meaning your body does not flush it out and it can accumulate problematically. If you have a health condition that you’re seeking to treat with supplement doses over 10,000 IU daily, be sure to consult with a medical professional.

Keep in mind, too, that ongoing exposure to the sun appears to maintain optimal blood levels of vitamin D more effectively than dietary intake.

While there are foods that contain vitamin D—most notably beef liver, egg yolks, and fatty fish like tuna, mackerel, and salmon—and high-quality vitamin D supplements are available, the consensus when it comes to sources of vitamin D is that the sun truly can’t be beat.

Get Your Vitamin D from the Sun

While there are clear benefits to sunscreen use, it does prevent your skin from generating vitamin D. “People are spending less time outside and, when they do go out, they’re typically wearing sunscreen, which essentially nullifies the body’s ability to produce vitamin D,” said Dr. Kim Pfotenhauer, a researcher on a clinical review published in the Journal of the American Osteopathic Association.

The review found that nearly 1 billion people worldwide may have insufficient levels of vitamin D, and that the cause, for a large percentage of those individuals, has to do with sunscreen use. “While we want people to protect themselves against skin cancer, there are healthy, moderate levels of unprotected sun exposure that can be very helpful in boosting vitamin D,” Pfotenhauer said.

The amount of time you need in the sun to maintain optimal levels of vitamin D depends on a variety of factors, including age, weight, skin color, diet, antioxidant levels, latitude and altitude, season, cloud cover and pollution, and time of day.

Learn about vitamin D deficiency.

Dr. Holick, one of the foremost experts on the relationship between vitamin D and human health, was the first to identify the mechanism that allows your skin to synthesize vitamin D. When using sunlight exposure to to increase the amount of vitamin D in your body, Holick recommends staying outside sunscreenless for about half the time it typically takes for you to get a mild sunburn. Another way to gauge when you’ve given your skin enough sun time is to look for the moment when it begins to turn a very light shade of pink.

Especially if you have darker skin, those markers may not work well for you. You may want to rely on the guidelines proposed by vitamin D experts at the National Institutes of Health (NIH), who recommend 5-30 minutes of sun exposure 2 to 3 times a week without sunscreen.

How Nutrition Impacts Immune System Function

There is no other physiological system more important to staying healthy than the immune system. In order for our immune system to operate at peak capacity, it’s essential that we provide it with key nutrients required to keep all the parts of the immune system healthy and fully functioning.

There is no other physiological system more important to staying healthy than the immune system. It protects us against infectious organisms and invaders that cause bodily harm. The vast majority of ailments and health problems we experience can be attributed to lapses in immune function and to oxidative stress and related inflammation.

In order for our immune system to operate at peak capacity, it’s essential that we provide it with key nutrients required to keep all the parts of the immune system healthy and fully functioning.

What Is the Immune System?

The immune system is a complex network of cells, cell products, tissues, and organs that collectively launch the immune response by utilizing a varied arsenal made up of macrophages, lymphocytes including the B cells (B meaning derived from bone marrow) and T cells (T meaning derived from the thymus), and antibodies.

Antibodies

An antibody is a blood protein produced in response to a particular class of foreign substances known as antigens. Antigens, short for antibody generators, include invaders like bacteria, viruses, and toxins. The defining characteristic of an antigen is that it binds to specific immune receptors, eliciting a certain immune response. Antibodies protect us by combining chemically with antigens, which renders them inactive and removes them from the body.

A healthy, fully-functioning immune system has the capacity to detect a wide variety of antigens and other microorganisms as well as to differentiate between potential threats and the body’s own healthy tissue.

White Blood Cells

White blood cells are like the scouts of the immune system’s army, constantly surveying the landscape for looming attacks. The human body produces and stores white blood cells in four different locations, which are collectively known as the lymphoid organs.

  • Bone marrow: This spongy tissue is found at the center of some bones, such as the hip and thigh bones, and contains immature cells known as stem cells that can develop into any kind of cell found in the human body.
  • Thymus: This small organ is situated beneath the breast bone where T cells mature.
  • Spleen: The largest lymphoid organ, it not only stores white blood cells but also helps to regulate the volume of blood in the body as well as to dispose of old or defective blood cells.
  • Lymph nodes: These small, bean-shaped structures produce and store infection and disease-fighting cells as well as the lymph fluid that transports them throughout the body.

Additionally, the liver is now recognized as an important contributor of factors involved in immune function.

Because the immune system is so complex, it’s often divided into subsystems in order to better conceptualize its operations. Two of the most important distinctions drawn are: 1) the innate immune system versus the adaptive immune system and 2) cellular immunity versus humoral immunity.

The Innate Immune System vs. the Adaptive Immune System

One way to conceive of the immune system is as a series of layered defenses designed to respond with increasing precision to threatening pathogens.

Physical barriers, like the skin, form the first line of defense against microorganisms like bacteria and viruses by simply preventing them from entering the body. If a pathogen successfully breaches the physical barriers, that activates the innate immune system. When a pathogen manages to evade the innate immune response, the adaptive immune system kicks into gear.

The adaptive immune system alters its response based on its recognition of the specific pathogen and its understanding of the most effective way to combat that pathogen. It retains this targeted response in the form of immunological memory, allowing it to become more and more effective at eliminating microorganisms it has encountered previously.

The ability of the immune system to distinguish between healthy tissues and foreign invaders such as antigens is a prerequisite for both innate immunity and adaptive immunity.

The Innate Immune System

Once a microorganism has made it past the physical barriers, the innate immune system works to neutralize that substance. This can happen either because pattern recognition receptors perceive components that belong to broad groups of microorganisms known to be foreign to the body, or because injured or stressed cells have sent out distress signals.

The innate immune response is non-specific, meaning it reacts to all foreign substances in the same way. That does not mean its response is simplistic, however. In fact, the innate immune system itself has many subcomponents, such as:

  • Surface barriers: This category includes mechanical, chemical, and biological barriers. The skin is the most obvious example of a mechanical barrier, and as previously mentioned, it forms the first line of defense against microorganisms. However, since the human body cannot thrive while completely sealed off from its environment, other, more porous surface barriers are needed too. For example, the respiratory tract secretes antimicrobial peptides that form a chemical barrier, while commensal flora in the gastrointestinal tract serves as a biological barrier.
  • Inflammation: This is one of the first ways the immune system responds to infection or injury. Increased blood flow to the affected tissue results in redness, swelling, heat, and pain. Injured or infected cells release eicosanoids, which produce fever and the dilation of blood vessels, and leukotrienes, which attract a kind of white blood cell called leukocytes.
  • Complement system: This biochemical cascade attacks the surfaces of foreign cells. It’s an important and rapid element of the immune response. Its name refers to how it complements the process by which antibodies kill pathogens.
  • Cellular barriers: Leukocytes, first mentioned in relation to inflammatory responses, play a vital role in the innate immune system’s response to threats. Innate leukocytes include phagocytes (a class that’s subdivided into macrophages, neutrophils, and dendritic cells), innate lymphoid cells, mast cells, eosinophils, basophils, and natural killer (NK) cells. These cells eliminate pathogens via multiple mechanisms, such as attacking through contact or engulfing and then killing the pathogens.

The Adaptive Immune System

Early vertebrates developed an adaptive immune response that can more effectively deal with threats thanks to immunological memory. The antigen-specific adaptive immune response occurs when the immune system recognizes an antigen and then launches a response informed by its knowledge of that specific antigen.

The adaptive immune system, like the innate immune system, has a number of subcomponents, including a number of different cell types.

  • Lymphocytes: This special form of leukocytes is unique to the adaptive immune system. Two of the major types of lymphocytes, B cells and T cells, come from hematopoietic stem cells in the bone marrow. B cells play a part in the humoral immune response while T cells contribute to the cellular immune response (more on that later).
  • Killer T cells:  This subgroup of T cells targets microorganisms carrying infectious diseases, other pathogens, and cells that have become damaged or dysfunctional. Killer T cells get activated when their T-cell receptor (TCR) binds to a specific antigen. T cells are particularly crucial when it comes to preventing the replication of viruses.
  • Helper T cells: When this group of T cells identifies a possibly dangerous microorganism, they send out stimulatory signals that activate microphages, killer T cells, and B cells. They contribute to both the adaptive and the innate immune response and help the body determine which immune response to use to combat a pathogen. They don’t attack pathogens themselves, but control the immune response by directing the activity of other cells.
  • Gamma delta T cells (γδ T cells): This class of T cells shares characteristics of helper T cells, cytotoxic T cells, and NK cells. Experts consider them an unconventional T cell subset and have yet to identify exactly what stimulates them into action. They blur the line between innate and adaptive immunity by participating in certain elements of both types of immune responses.
  • B lymphocytes and antibodies: Activated B cells divide to create plasma cell offspring, which then secrete millions of copies of an antibody formulated in response to the presence of a specific antigen. The antibodies then circulate in the bloodstream and lymphatic system, binding to the antigens and marking them for elimination or neutralizing them immediately.

There is no other physiological system more important to staying healthy than the immune system. It protects us against infectious organisms and invaders that cause bodily harm. The vast majority of health problems can be attributed to lapses in immune function and to oxidative stress and related inflammation.

Cellular Immunity vs. Humoral Immunity

The other important division related to the immune system has to do with cellular immunity and humoral immunity.

Cellular immunity involves mostly T cells and carries out immune responses to cells that are altered in a specific way, including cancer cells, transplanted cells, and cells invaded by pathogens.

The humoral response, sometimes referred to as the antibody‐mediated response, involves B cells that recognize antigens or pathogens that circulate in the lymph or blood.

Passive Immunity

This is not an ongoing operational state of the immune system, but it’s nonetheless worth addressing. Passive immunity refers to an immune system response that is, in essence, borrowed from another source rather than generated innately.

For example, during the gestational period, a fetus receives antibodies from the placenta. Breast milk also contains antibodies that bolster infants’ immune systems after birth. This type of passive immunity can protect babies and toddlers from bacterial infections and other threats during their first years of life.

Understanding Disorders of the Immune System

Given the complexity of the immune system, it’s hardly surprising that it can malfunction in a multitude of ways. Immune system disorders arise because the immune system responds too aggressively, which is known as hypersensitivity; fails to respond aggressively enough, which is known as immunodeficiency, or responds in the wrong way, which is known as autoimmunity.

Hypersensitivity

Immune system hypersensitivity describes any instance in which the immune system overreacts, thereby causing collateral damage to healthy cells.

Allergic reactions are a classic example of immune system hypersensitivity. With anaphylactic shock, the immune system response to the presence of an allergen is so intense, it can be fatal.

Immunodeficiency

Immunodeficiency is the flip side of hypersensitivity. A number of underlying conditions and factors can lead to immune deficiency, such as:

  • Age
  • Obesity
  • Alcoholism
  • Malnutrition

It’s also possible to develop acquired immunodeficiency as the result of another disease, as can happen in patients with HIV/AIDS or cancer. In some cases, immunodeficiency has genetic causes, such as severe combined immunodeficiency (SCID) or chronic granulomatous disease.

Autoimmunity

The uniting characteristic of autoimmune disorders is that the body’s ability to differentiate between healthy tissue and pathogens or faulty cells becomes compromised. This causes the immune system to begin to target healthy cells.

There are a variety of autoimmune diseases, all of which affect the body in different ways. Some common ones include:

There is no other physiological system more important to staying healthy than the immune system. It protects us against infectious organisms and invaders that cause bodily harm. The vast majority of health problems can be attributed to lapses in immune function and to oxidative stress and related inflammation.

How Nutrition Impacts Immune System Function

Nutrition is a critical determinant of immune function capability, and malnutrition is one of—if not the—most common cause of immunodeficiency. According to an article published in Trends in Immunology, “Malnutrition, which encompasses under- and over-nutrition, is responsible for an enormous morbidity and mortality burden globally.”

Low-protein intake as well as deficiency or suboptimal intakes of single nutrients results in altered immune responses. The levels of zinc, selenium, iron, copper, vitamins A, C, E, and B-6, and folic acid in a person’s diet all strongly influence immune system function.

Additionally, certain elements of a person’s diet and lifestyle may degrade immune function. Two major culprits are excessive alcohol consumption and drug use, which harm the body’s immune system in two ways. First, they deplete the body of many of the key nutrients required for immunocompetence, such as zinc, B vitamins, and folic acid. Second, they directly impair cells and molecules that shape the immune response. The liver plays an important role in producing specialized proteins as part of the immune response, and direct damage to liver cells by ethanol or other drugs can also compromise immune function.

Differentiating Between Acute and Chronic Inflammation

It’s worth circling back to one element of the immune system response—inflammation—to clarify some misconceptions about this physical process.

When we talk about inflammation, we rarely bother to differentiate between chronic inflammation and acute inflammation, but grasping that distinction is a vital part of learning how to optimize immune system function as well as your overall health and well-being.

When all is going well, inflammation is simply another way in which the immune system acts to heal injured body parts.

Acute inflammation occurs in response to a specific injury, such as an infected cut or an ingrown toenail. It is characterized by redness, swelling, and soreness around the injured tissue as white blood cells infiltrate the area to destroy germs, dead and damaged cells, and other foreign material.

Chronic inflammation, far from being a part of the healing process, can have quite a destructive effect. Many of us today worry about how chronic systemic inflammation might be eroding our health, and for good reason. Researchers have identified a number of lifestyle and environmental factors that can result in chronic inflammation, such as:

  • Excess body weight
  • Poor diet
  • Lack of exercise
  • Stress
  • Smoking
  • Pollution
  • Poor oral health
  • Illicit drug use
  • Heavy alcohol consumption

There is a specific physiological basis to this type of inflammation related to the release of pro-inflammatory cytokines from immune-related cells. The term cytokine refers to a number of substances, such as small proteins like interferon, interleukin, and growth factors. These immune cells have an effect on other cells which, when released throughout the body, can result in the chronic activation of the immune system.

Control of both types of inflammation may be disrupted by an inadequate supply of either macronutrients (protein in particular) or micronutrients. A strong immune system then, is dependent upon proper nutritional strategies that fortify and optimize function. An immune system replete with solid antioxidant and anti-inflammatory defenses is absolutely necessary for good health and can be assured by a combination of proper nutrition, rest, and an active lifestyle.

The Relationship Between Antioxidants and the Immune System

No discussion of the connection between nutrition and immune function would be complete without at least a nod to antioxidants. While the immune system does not include an antioxidant component per se, the two are tightly intertwined in that antioxidant protection is crucial to maintaining a strong, vital immune system.

Antioxidants and anti-inflammatories are important tools in the repertoire of the immune system. Antioxidants are agents that inhibit the oxidation of other molecules. Oxidation is a chemical reaction that can produce free radicals, leading to chain reactions that may damage cells.

Free radicals or reactive oxygen species (ROS) are highly reactive compounds that adversely alter the structure and integrity of lipids and proteins, including many of the protein components of the immune system. They can attack at several sites, often starting at the level of DNA itself.

If the DNA of a compound is altered, it will ultimately lead to mutations and genomic instability. These changes could result in the development of a variety of cancers or inflammation. It has been proposed that the process of aging is in part due to accumulation of DNA damage.

Oxidative damage that changes the chemical structure of a compound will almost always affect its function, given the precision with which biological compounds are designed. Lipid membranes are very susceptible to peroxidation, the oxidative degradation of lipids in which free radicals steal electrons from the lipids in cell membranes. This damage leads to leaky membranes and loss of cellular integrity and function.

Damage of this nature to cells involved with immune function will compromise the ability of the immune system to ward off bacteria, viruses, and other harmful compounds. The body relies on internal and external sources of antioxidants to assist in coping with this oxidative stress. Not coincidentally, many nutrients shown to boost the immune system have significant antioxidant properties, such as vitamin E, vitamin C, beta-carotene, selenium, copper, iron, and zinc. Dietary antioxidants are important in establishing resistance to infectious pathogens.

Can Nutrients Boost Immune System Function?

Although more research needs to be done to quantify the precise effects of various nutrients on the immune system, as well as the effects of nutrition on the development (as opposed to the treatment) of diseases, the studies that have been conducted so far certainly indicate connections between micronutrient deficiencies and immune response.

As mentioned in the preceding sections, without an adequate supply of certain nutrients, the immune system is unable to operate at peak capacity. Studies done with animals have shown that deficiencies of the following nutrients adversely impact immune function:

  • Zinc
  • Selenium
  • Iron
  • Copper
  • Folic acid
  • Vitamin A
  • Vitamin B6
  • Vitamin C
  • Vitamin E

It’s important to note that the interrelationship between deficiencies of those nutrients and overall health has yet to be demonstrated, and controlled studies with human subjects have yet to be carried out. However, given that eating a balanced, nutritious diet rich in the nutrients above will certainly not harm your health, there’s no reason to hold off on prioritizing your intake of those vital nutrients.

There is no other physiological system more important to staying healthy than the immune system. It protects us against infectious organisms and invaders that cause bodily harm. The vast majority of health problems can be attributed to lapses in immune function and to oxidative stress and related inflammation.

If you’re concerned that diet alone will not meet your micronutrient needs, due to ethical restrictions, allergies and food sensitivities, or simply personal preferences, it may be valuable to seek out high-quality supplements to fill in the gaps. For instance, if you’re worried your diet may not provide an optimal amount of protein to meet your body’s amino acid needs, adding a well-formulated essential amino acid supplement, such as the Amino Co. essential amino acid blends, can make up the difference.