Learn how to spot signs of nutrient deficiencies and toxicities, which health conditions put you at risk, and how to avoid social media myths, marketing ploys, and misinformation to make better decisions in food choices and eating habits.

Before we can launch into this week’s topic, it’s important to define the difference between macronutrients and micronutrients because I believe most people think of supplements when it comes to meeting their micronutrient needs.

A macronutrient is a large molecule that supplies us with the energy (or calories) that we need. This comes from carbohydrates, protein, and fat sources in food, and is what I refer to as the “quantity” of our diet. The “quality” of our diet is based in foods that supply us with micronutrients, aka vitamins and minerals.

A balanced, varied diet is all you need to meet your daily requirements of both macros and micros, but I recognize that not everyone might be able to meet those requirements and, as always, I also recognize that Social Determinants of Health (SDOH)—education, location, environment, to name a few—also play a huge role in how people are able to access and afford nutritious food and that health outcomes may be outside of an individual’s control.

Micronutrient Distinctions

Micronutrient toxicity occurs when excessive amounts of essential vitamins and minerals are consumed, surpassing the body’s capacity to process and utilize them effectively. In this case, it is highly unlikely for someone to consume toxic amounts of micronutrients, so this is usually more of an issue when people take excessive doses of supplements, but there could also be malabsorption issues related to altered gastrointestinal functions where micronutrients may not be properly processed and build up in the body.

Micronutrient deficiency refers to a condition where the body lacks essential vitamins and minerals necessary for proper growth, development, and maintenance of health [1]. Micros are required in small amounts (hence the prefix “micro-“) and include vitamins like A, B12, folate, and minerals such as iron and calcium. Insufficient intake or poor absorption can lead to specific health issues such as anemia (from iron deficiency), impaired immune function, and developmental delays during pregnancy or childhood. This highlights the critical need for adequate dietary diversity and supplementation where necessary. As a rule, I recommend people only supplement when they can’t get what they need from their diet and they have received a confirmed deficiency from their doctor; otherwise, it could be a waste of money.

For those of us studying to be Registered Dietitians, in our school textbooks, we learn about the Dietary Reference Intakes. The DRI is the general term for a set of reference values used to plan and assess nutrient intakes of healthy people. These values, which vary by age and sex, include:

• Recommended Dietary Allowance (RDA): The average daily level of intake sufficient to meet the nutrient requirements of nearly all (97–98%) healthy individuals [3]. This is what I use to help my patients plan nutritionally adequate diets to support their stage of life and physical activity.
• Tolerable Upper Intake Level (UL): The maximum daily intake unlikely to cause adverse health effects. An example of this would be calcium. The daily RDA for women is 1,000-1,200 mg, but anything more than 2,500 mg would be considered a toxic level.

Risk Factors

As we get older, our bodies become less efficient at absorbing and using certain nutrients. For example, Vitamin B12 absorption decreases due to lower stomach acid levels. Calcium absorption can also drop off, increasing bone health concerns.

Certain long-term health conditions can directly affect how your body processes or stores nutrients. Kidney or liver disease can impair how fat-soluble vitamins (like A and K) are metabolized. Digestive disorders like Crohn’s, celiac, or even low stomach acid can interfere with the absorption of nutrients like iron, calcium, and B12.

Some medications, especially when taken long-term, can lead to micronutrient issues. Proton pump inhibitors (PPIs) can reduce B12 and magnesium absorption. Diuretics (often prescribed for blood pressure) can flush out potassium and magnesium. Metformin, a common diabetes medication, has been linked to B12 deficiency. If you’re taking any long-term meds, it’s worth asking your healthcare provider about possible nutrient interactions.

When access to nutritious food is limited—whether due to finances, location, or other barriers—people may not get enough essential vitamins and minerals. Even when calories are sufficient, diets heavy in processed or ultra-processed foods can be low in micronutrients.

Some groups have higher needs or face unique challenges when it comes to getting (or retaining) enough nutrients:

• Pregnant and breastfeeding women – Nutrient needs increase, especially for folate, iron, iodine, and DHA.
• People with heavy periods – Higher risk for iron deficiency.
• Older adults – As mentioned, absorption issues plus polypharmacy (taking multiple meds) raise risk.
• Vegetarians and vegans – May fall short in B12, iron, zinc, or omega-3s without careful planning or fortified foods.
• People with food allergies – Eliminating entire food groups can lead to gaps in nutrient intake.
• Crash dieters or restrictive eaters – Less food means fewer nutrients.
• People who smoke, drink excessively, or use recreational drugs – These habits can deplete key nutrients or increase the body’s needs.
• People with malabsorption syndromes – Think celiac, IBS, or chronic diarrhea, which all reduce nutrient uptake.

Whether due to age, health, lifestyle, or diet, many people are at risk of developing micronutrient imbalances—even if they eat regularly or take supplements. Understanding your own risk factors can help you take proactive steps, like talking to a healthcare provider, checking your blood levels, or adjusting your diet.

Common Nutrient Deficiencies (From Food, Not Supplements)

Even in developed countries, people can fall short on essential nutrients—often because their diets lack variety or key nutrient-rich foods. Below are some of the most common deficiencies, how they happen, and what can go wrong if they’re left untreated [2].

Vitamin B12

Found mainly in animal products and fortified foods, vitamin B12 is essential for nerve health, red blood cell production, and brain function. Deficiency is especially common in older adults due to reduced stomach acid (a condition called atrophic gastritis), which makes it harder to absorb B12 from food. Certain medications—like proton pump inhibitors (PPIs) and metformin—can also interfere with absorption. Other risk factors include GI conditions like Crohn’s or celiac disease, or a history of bariatric surgery.

What happens if you’re deficient? You might feel fatigued, experience numbness or tingling, struggle with memory, or even develop balance issues if it’s left untreated.

Vitamin D

Vitamin D is tricky—it’s found in fatty fish, egg yolks, and fortified foods, but we also make it through sun exposure. That’s where many people run into problems. Limited time outdoors, darker skin, aging skin, and certain kidney or liver disorders can all reduce the body’s ability to produce or activate vitamin D. Not eating enough fortified foods just adds to the problem.

Why does it matter? Deficiency can lead to bone weakening, increased risk of osteoporosis, muscle weakness, and even falls, especially in older adults.

Calcium

We all know calcium is crucial for strong bones, but many people still don’t get enough—especially if they avoid dairy or don’t eat many calcium-fortified foods, leafy greens, or fish with edible bones (like sardines). Vitamin D deficiency can also impact calcium absorption, and aging further reduces the efficiency of bone remodeling.

The risks? Chronic calcium deficiency can lead to bone loss, fractures, and osteoporosis.

Folate (Vitamin B9)

Folate is abundant in leafy greens, legumes, citrus fruits, and fortified grains. But poor diet, alcohol use, malabsorption conditions, or medications like methotrexate (used for arthritis, psoriasis, and some cancers) can lead to deficiency.

Why it matters: Folate is vital for DNA synthesis and red blood cell formation. Low levels can cause anemia, elevated homocysteine (a heart disease risk marker), and—in pregnant people—can increase the risk of neural tube defects (NTDs) in babies.

Iron

Iron comes in two forms: heme iron (from animal sources) and non-heme iron (from plants), the latter of which is best absorbed when paired with vitamin C-rich foods. Deficiency can result from low dietary intake, chronic blood loss (such as from ulcers or GI bleeding), heavy menstrual cycles, or gut disorders like celiac disease or IBD.

What to watch for: Iron deficiency can cause anemia, fatigue, and weakened immune function.

Magnesium

Magnesium plays a role in hundreds of enzymatic reactions in the body. You’ll find it in foods like legumes, seeds, nuts, whole grains, leafy vegetables, and yogurt. Still, many people come up short—especially if they’re taking diuretics, eating a low-quality diet, or dealing with chronic GI issues (like diarrhea or inflammatory bowel disease).

Deficiency symptoms can include muscle cramps, irregular heart rhythms, and fatigue.

Nutrient deficiencies don’t always scream for attention—they often show up as vague symptoms like tiredness, brain fog, or frequent colds. But over time, they can lead to serious health issues. Eating a varied, whole-food diet is your best defense, but knowing where your risk factors lie can help you stay one step ahead.

Common Nutrient Toxicities (From Supplements, Not Food)

While most people worry about not getting enough nutrients, it’s also possible to have too much of a good thing—especially when it comes to supplements. Unlike food sources, which rarely cause toxicity, high-dose vitamins and minerals in pill or powder form can push your intake past safe limits. Here are some of the most common offenders:

Vitamin A

Too much vitamin A usually comes from overdoing supplements or eating large amounts of liver. Speaking of, the risk is even higher if your liver isn’t functioning well, since that’s where vitamin A is stored and cleared.

What can go wrong? Excess vitamin A can lead to liver damage, bone loss, and headaches. In pregnancy, very high doses can be teratogenic—meaning they can cause birth defects.

Vitamin B6

Unlike most B vitamins, B6 is not water-soluble in high doses and can build up in the body. Toxicity usually results from taking high-dose supplements over time.

Side effects? Too much B6 can cause nerve damage, leading to sensory neuropathy and poor muscle coordination (ataxia). Ironically, the symptoms of toxicity can resemble a deficiency.

Calcium (Hypercalcemia)

Too much calcium—usually from over-supplementing or from vitamin D toxicity—can raise blood calcium levels, a condition called hypercalcemia. High vitamin D increases calcium absorption from food and bone, compounding the issue.

Risks include: Kidney stones, constipation, and interference with the absorption of other essential minerals. Overcorrecting for osteoporosis with supplements is a common culprit.

Iron

Iron overload can happen two ways: from a genetic condition called hemochromatosis or from taking too many iron supplements without medical guidance. Unlike iron from food, supplement iron can accumulate dangerously if there’s no true deficiency.

Why it matters: Excess iron can damage the liver, heart, and pancreas, and cause symptoms like joint pain and fatigue. Over time, it can contribute to conditions like diabetes or cirrhosis.

Sodium

While technically not a vitamin or mineral we think of in supplement form, sodium toxicity is worth mentioning. It’s more often the result of a highly processed diet rather than supplements, but the effects are real.

Too much sodium can lead to high blood pressure (hypertension), which raises the risk of heart disease, stroke, and kidney problems.

Water (Yes, Even Water)

Believe it or not, it is possible to drink too much water—particularly among endurance athletes or people taking certain medications like SSRIs or thiazide diuretics. This can cause hyponatremia, a dangerous condition where sodium levels in the blood drop too low.

Symptoms can include: Confusion, headaches, seizures, and in severe cases, coma or death.

Marketing Myths, Misinformation, and Social Media Hype

If you’ve spent more than five minutes on social media or in a supplement aisle, you’ve probably come across bold claims like “boost your immunity,” “detox your liver,” or “get glowing skin with this superfruit smoothie powder!” While some of these messages are rooted in partial truths, many are exaggerated, misleading, or simply designed to sell you something you probably don’t need [4].

Despite what influencers and juice cleanses might tell you, your body comes with a built-in detox system—and it’s incredibly effective if you’re generally healthy. Your liver filters out harmful substances and metabolizes nutrients. Your kidneys flush toxins out through urine (that’s why drug tests use urine!). The skin, lungs, intestines, and immune system all play active roles in defending against and eliminating foreign substances. You don’t need expensive supplements, teas, or cleanses to “flush out toxins”—just focus on the basics: eat a nutritious diet, drink enough water, sleep well, and move your body regularly.

If you’re feeling unwell or experiencing symptoms like persistent fatigue, weight changes, or digestive issues, skip the detox smoothie and see your doctor instead.

Red Flags in Product Marketing

Food and supplement marketing is often full of buzzwords and deceptive tactics. Here are a few to watch for:

• Vague or exaggerated health claims like “gut-healthy,” “immune-boosting,” or “made with real fruit” sound appealing but often lack scientific backing—or rely on tiny amounts of the advertised ingredient alongside a whole lot of sugar or additives.
• “All-natural” doesn’t mean healthy. A granola bar labeled “natural” may still be packed with added sugars, oils, and processed ingredients. My personal pet peeve? “Natural peanut butter” that sneakily includes sugar and palm oil.
• Long or confusing ingredient lists with unrecognizable words (especially anything ending in “-ose,” like glucose or fructose) can signal high sugar content or unnecessary additives.
• “Low-fat” often means high-sugar or high-sodium. When food manufacturers take out fat, they often add sugar or salt to make the product palatable again. That “healthy” choice might not be so healthy after all.
• Packaging tricks like rainbow colors, “clean” fonts, or wellness-style branding can make unhealthy products look wholesome. Be skeptical of pretty labels.
• Some products don’t follow FDA labeling rules. When companies make unsupported health claims or skip proper labeling, you’re left with products that may not be safe or effective [5].

Let’s clear this up once and for all: you can’t “boost” your immune system in the way most products claim. Vaccines “boost” immunity (i.e., strengthen or support) by training your immune system to recognize and fight specific viruses or bacteria [6]. That’s a targeted, scientific process. What supplements like vitamin C, zinc, or echinacea can do is support normal immune function—but only if you were deficient to begin with. If your nutrient levels are already adequate, taking extra won’t give your immune system superhero powers.

The bottom line: if it sounds too good to be true, it probably is.

Learn more about environmental exposure to toxic chemicals—especially those found in cosmetics and textiles—with Regan Nelson, who is on a mission to share her knowledge and resources needed to live a safer, healthier, and more sustainable life.

How to Evaluate Your Nutrient Intake (Without Losing Your Mind)

Between confusing labels, flashy marketing, and conflicting advice online, figuring out whether you’re getting the right amount of nutrients can feel overwhelming. Here’s a simple, grounded approach to help you assess your own intake and make informed decisions:

The front of a food package is basically advertising—bright colors, wellness buzzwords, and feel-good phrases like “immune support” or “all-natural.” Flip it around.

The Nutrition Facts Label (NFL) and the ingredients list on the back are where the truth lives [7]. Pay attention to:

• Serving sizes
• Added sugars
• Sodium and saturated fat content
• Vitamins and minerals per serving

This is where you’ll find facts, not fiction.

Editor’s Note: The FDA is currently working on a front-of-package (FOP) label that will call out things like saturated fats, sodium, and added sugars to help consumers decide if a particular packaged food should be included in their diet. Click here to learn more.

As mentioned above, supplements can help fill in gaps, but they’re not a substitute for a balanced diet. Whenever possible, aim to meet your nutrient needs through whole foods: fruits, vegetables, whole grains, nuts, seeds, dairy, and lean proteins. Processed foods aren’t off-limits, but choose options with simple ingredient lists and minimal additives.

Before Googling your way into a supplement spiral, bookmark the Office of Dietary Supplements (ODS) which offers evidence-based, up-to-date information on vitamins, minerals, and supplements (without the sales pitch).

Lastly, always, ALWAYS, check in with a registered dietitian, doctor, or pharmacist before starting (or stopping) any supplement, changing your diet drastically, or adjusting medications. Medical doctors in particular can order bloodwork to check for deficiencies, help you avoid harmful interactions, and recommend safe and effective doses. If you do supplement, do it safely by looking for third-party certifications from organizations like USP (U.S. Pharmacopeia) or NSF International. These seals mean the supplement has been tested for quality, purity, and potency. And always avoid megadoses unless specifically advised by a healthcare provider [8]. Taking large amounts of certain vitamins—especially fat-soluble ones like A or D—can cause toxicity and liver damage over time.

Bottom Line

Nutrition isn’t about perfection; it’s about informed, sustainable choices. A well-rounded diet will cover most of your needs, but in today’s world, thoughtful supplement use may sometimes be necessary. Just make sure you’re doing it with your eyes wide open—and ideally, with some professional guidance.

References

1. Espinosa-Salas, S., & Gonzalez-Arias, M. (2023, September 21). Nutrition: Micronutrient Intake, Imbalances, and Interventions. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK597352/
2. Kiani, A. K. (2022). Main nutritional deficiencies. Journal of Preventive Medicine and Hygiene, 63(2 Suppl 3), E93–E101. https://doi.org/10.15167/2421-4248/jpmh2022.63.2S3.2752
3. National Institute of Health. (2021). Nutrient Recommendations and Databases. Ods.od.nih.gov; National Institutes of Health. https://ods.od.nih.gov/HealthInformation/nutrientrecommendations.aspx
4. ‌Harvard Health Publishing. (2008, May 1). The dubious practice of detox – Harvard Health. Harvard Health; Harvard Health. https://www.health.harvard.edu/staying-healthy/the-dubious-practice-of-detox
5. ‌FDA. (2019). Guidance For Industry Food Labeling Guide. U.S. Food and Drug Administration. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-industry-food-labeling-guide
6. ‌MD, R. H. S. (2023, September 11). Immune boosts or busts? From IV drips and detoxes to superfoods. Harvard Health. https://www.health.harvard.edu/blog/immune-boosts-or-busts-from-iv-drips-and-detoxes-to-superfoods-202309112972
7. ‌Woffindin, L. (2024, October 30). Food Labels in Promoting Health and Safety | The Role | Innovations. CPD Online College. https://cpdonline.co.uk/knowledge-base/food-hygiene/food-labels-health-safety/
8. ‌USP vs. NSF Certification. (2025). EyePromise. https://eyepromise.com/eyepromise-blog/usp-vs-nsf-certification/