We spend a lot of time talking about nutrition at Parenthood Wellness, but there’s something about nutrients that I find even more fascinating than what’s on our plates: what happens to them once they’re inside our bodies.

Every second, trillions of cells are performing countless biological processes that depend on vitamins, minerals, amino acids, and fatty acids. Iron is helping deliver oxygen to our tissues. B vitamins are participating in energy production and DNA synthesis. Zinc is supporting hundreds of enzymes involved in everything from cellular growth to immune function. Calcium is helping nerve cells communicate, muscles contract, and bones maintain their structure.

And during periods of rapid development, like preconception, pregnancy, and childhood, these nutrients take on even greater importance. They’re involved in the development of reproductive cells, the formation of new tissues and organs, and the growth of biological systems that children will depend on for the rest of their lives.

But here’s the part that makes nutrition so interesting:

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Eating enough of a nutrient doesn’t necessarily mean your body has enough of it.

Nutrient absorption varies, requirements change throughout life, and certain health conditions or medications can influence how much is available to the body. Someone can eat a nutrient-dense diet and still develop a deficiency, while another person may be taking supplements they don’t actually need.

That’s one of the reasons we love thoughtful nutrient testing. Not because we want everyone taking dozens of supplements or chasing perfect laboratory numbers, but because understanding your individual nutritional status can help us identify meaningful gaps, make better decisions, and support the body’s ability to function as it should.

And sometimes, the implications extend far beyond how we feel today.

Small nutrients, enormous implications

One of the most remarkable things about nutrition is how a relatively small amount of a particular nutrient can make an enormous difference during a critical period of development.

Consider folate. In the earliest weeks of pregnancy, the neural tube is forming the structure that will eventually become the baby’s brain and spinal cord. This process occurs so early that many women don’t yet know they’re pregnant. Adequate folic acid intake before and during early pregnancy significantly reduces the risk of neural tube defects, serious birth defects affecting the brain and spinal cord.

Think about that for a moment. A vitamin measured in micrograms can influence one of the earliest and most important structural events in human development.

It’s one of the clearest examples we have of how meeting a nutritional requirement at the right time can meaningfully change a health outcome.

Iodine offers another fascinating example. The thyroid gland uses iodine to produce thyroid hormones, which regulate metabolism and play essential roles in fetal brain development. During early pregnancy, the developing baby depends heavily on the mother’s thyroid hormones. Severe iodine deficiency during this period can cause profound neurological impairment, making adequate iodine intake an important part of preconception and pregnancy nutrition.

Then there’s iron, a nutrient that’s especially interesting because its role extends well beyond preventing anemia. Iron is necessary for oxygen transport, but it’s also involved in mitochondrial energy production, neurotransmitter metabolism, and myelination, the process of developing the protective coating around nerve fibers. Significant iron deficiency during infancy and early childhood has been associated with differences in cognitive, motor, and behavioral development, particularly when it occurs during periods of rapid brain growth.

These examples are powerful because they show that nutritional adequacy isn’t simply about avoiding fatigue or maintaining good laboratory values. Certain nutrients participate in developmental processes that happen during specific windows of time. Meeting those needs can support healthy development, while significant deficiencies may have consequences that extend beyond the period when the deficiency occurred.

This doesn’t mean every nutrient needs to be at the upper end of a laboratory range, or that taking extra nutrients will produce an even healthier baby. The goal is adequacy, not excess. But it helps explain why identifying meaningful deficiencies before or during important developmental periods can be so valuable.

Why nutrient status matters before conception

Most people don’t start thinking seriously about nutrition until pregnancy begins, but reproductive development is already underway long before the positive pregnancy test.

Sperm take approximately two to three months to develop and mature, while eggs undergo important stages of follicular development and maturation in the months leading up to ovulation. During these processes, reproductive cells depend on normal DNA synthesis, energy production, and other cellular functions that require an adequate supply of essential nutrients.

Folate, vitamin B12, zinc, iron, and other nutrients participate in biological pathways relevant to reproductive health. Nutritional deficiencies can interfere with normal physiology, although it’s important to distinguish these established biological roles from claims that supplementation will necessarily improve egg quality, sperm quality, or pregnancy rates.

Preconception is also an opportunity to identify nutritional concerns before pregnancy increases the body’s demands. Someone who begins pregnancy with depleted iron stores, for example, may have a harder time meeting the substantial increase in iron requirements that occurs during the second and third trimesters. Someone following a vegan diet may need particular attention to vitamin B12, iodine, iron, and other nutrients. And people with certain digestive disorders may have difficulty absorbing nutrients even when dietary intake appears adequate.

What I love about the preconception window is that it gives us time to understand these factors before the demands of pregnancy begin. Rather than automatically recommending the same supplement regimen to everyone, we can consider dietary patterns, medical history, and targeted laboratory testing to identify where additional support may actually be useful.

Pregnancy: when your body’s nutritional priorities change

Pregnancy is an extraordinary example of how nutrient requirements can shift in response to physiology. Over approximately nine months, the body expands its circulation, develops the placenta, supports fetal growth, and prepares for childbirth and lactation. Each of these processes places demands on the body’s available nutritional resources.

Iron is one of my favorite examples because the changes are so dramatic. By late pregnancy, maternal blood volume has typically increased by approximately 40–50%, requiring substantial additional red blood cell production. At the same time, iron is transferred across the placenta to support the baby’s growth and help establish their iron stores for the first months after birth.

What’s particularly interesting is that the body’s need for absorbed iron increases severalfold between early and late pregnancy. This helps explain why someone can begin pregnancy with adequate iron stores but experience significant depletion by the third trimester.

This is one reason we favor monitoring ferritin throughout pregnancy, alongside the complete blood count and other testing when appropriate. While ferritin testing every trimester isn’t a universal prenatal guideline recommendation, following iron stores can provide additional context for individualized care.

Pregnancy also illustrates why more supplementation isn’t automatically better. Nutrients such as vitamin A, iodine, selenium, and iron are essential, but excessive intake can be harmful. Someone with documented iron deficiency may benefit from therapeutic supplementation, while someone with adequate iron stores may not need additional high-dose iron beyond their routine prenatal intake.

The goal is to understand what the body needs at a particular stage, provide an appropriate amount, and avoid assuming that higher doses always produce better outcomes.

Childhood: building the body’s long-term reserves

After birth, nutritional needs continue to evolve as babies and children grow. The brain is developing neural connections, the immune system is maturing, and bones are accumulating the mineral density that will help support skeletal health later in life.

One of the most fascinating examples is bone development. We often associate osteoporosis with older adults, but the foundation for bone health is established much earlier. Much of our peak bone mass is accumulated during childhood and adolescence, and the amount we build contributes to the reserves we carry into adulthood.

Calcium, vitamin D, adequate protein, and regular weight-bearing movement all support this process. Greater peak bone mass is associated with a lower risk of osteoporosis and fragility fractures later in life, which means childhood nutrition and physical activity can have implications that extend decades beyond the growing years.

Iron is another nutrient that deserves special attention during infancy. Babies are born with iron stores accumulated during pregnancy, particularly during the third trimester. However, breast milk naturally contains relatively little iron, and those prenatal stores gradually decline as babies grow. By around six months, infants generally need additional iron from complementary foods or supplementation when medically indicated.

This is especially important because iron participates in neurological development during a period of rapid brain growth. Severe or prolonged deficiency can interfere with normal development, and identifying and correcting deficiency early is an important part of pediatric care.

What’s important to remember is that children don’t benefit from receiving more of every nutrient than they need. Excessive supplementation can create imbalances or even toxicity, and many healthy children can meet their nutritional requirements through an appropriate diet.

At Parenthood Wellness, our interest in nutritional assessment is rooted in understanding whether a child’s needs are being met, particularly when dietary restrictions, digestive concerns, growth patterns, or medical history suggest that a deficiency may be possible.

Why eating a healthy diet doesn’t always tell the whole story

Here’s where nutrition becomes especially interesting.

Imagine two people eating the exact same meal. They’re getting the same amount of iron, zinc, protein, and other nutrients on paper, but that doesn’t necessarily mean their bodies will absorb and use those nutrients in the same way.

Nutrient bioavailability refers to how much of a nutrient can be absorbed and made available for use within the body. It’s influenced by the form of the nutrient, the foods consumed alongside it, digestive function, existing nutrient stores, and sometimes medications or medical conditions.

Iron provides a great example. The heme iron found in animal foods is generally absorbed more efficiently than the nonheme iron found in plant foods. But even nonheme iron absorption can change substantially depending on what else is eaten during a meal. Vitamin C enhances absorption, while compounds in tea and coffee can reduce it.

Your body also adjusts the amount of iron it absorbs based partly on its existing stores. When iron reserves are low, regulatory mechanisms generally allow more iron to be absorbed. When stores are adequate, absorption is more tightly limited.

Vitamin B12 works differently. Absorbing B12 from food requires several coordinated digestive steps, including the release of B12 from food proteins in the stomach and its subsequent binding to intrinsic factor, a protein necessary for absorption in the small intestine. Conditions such as pernicious anemia, certain gastrointestinal disorders, and some medications can interfere with this process.

These are just a few examples of why nutritional status involves much more than calculating nutrient intake. The body needs to digest, absorb, transport, store, and utilize nutrients, and disruption at any of these stages may affect availability.

This is also why I love pairing thoughtful nutrition education with individualized assessment. We can focus on eating nutrient-dense foods while also considering whether something may be interfering with the body’s ability to use them.

Three ways to get more from the nutrients you eat

The good news is that supporting nutrient absorption doesn’t require complicated routines or an enormous supplement collection. Some of the most useful strategies involve understanding how foods interact, supporting normal digestion, and making sure your intake matches your individual needs.

01Learn which nutrients work better together

Some of the easiest ways to improve nutrient absorption involve simple changes to how we combine foods.

One of the best examples is pairing plant-based iron sources with vitamin C. Nonheme iron, found in foods such as lentils, beans, tofu, leafy greens, and seeds, is generally less efficiently absorbed than the heme iron found in meat and seafood. Vitamin C helps keep nonheme iron in a form that’s easier for the body to absorb.

This makes combinations like lentils with tomatoes, black beans with bell peppers, or an iron-rich meal with citrus fruit particularly useful. You don’t need to calculate exact amounts of vitamin C at every meal. Simply incorporating vitamin C-rich produce alongside plant sources of iron can be beneficial.

On the other hand, tea and coffee contain polyphenols that can inhibit nonheme iron absorption when consumed with meals. For someone with low iron stores, drinking these beverages between meals rather than alongside iron-rich foods may be a helpful adjustment.

Fat-soluble vitamins provide another great example. Vitamins A, D, E, and K depend on normal fat digestion for absorption, so consuming foods containing these nutrients with some dietary fat can help. Think about adding olive oil to a colorful salad, serving roasted vegetables with avocado, or enjoying vitamin A-rich vegetables as part of a meal containing healthy fats.

Food preparation can also influence mineral availability. Beans, lentils, whole grains, nuts, and seeds contain phytates, naturally occurring compounds that can reduce the absorption of minerals such as iron and zinc. Soaking, sprouting, fermenting, and cooking certain foods can help reduce phytate content, although these foods remain nutritious even without special preparation.

The goal isn’t to turn every meal into a chemistry experiment. It’s simply to understand that the foods we eat together can influence how nutrients are absorbed, and a few thoughtful combinations can help us get more nutritional value from the foods we already enjoy.

02Support the digestive system that absorbs your nutrients

Before nutrients can be used by the body, most must be broken down and absorbed through the digestive tract. This involves a coordinated process between stomach acid, digestive enzymes, bile, the intestinal lining, and specialized nutrient transporters.

Different nutrients rely on different parts of this system. Protein digestion begins in the stomach and continues in the small intestine. Dietary fats require bile and pancreatic enzymes for efficient digestion and absorption. Vitamin B12 depends on intrinsic factor and a functioning terminal ileum, while iron absorption occurs primarily in the upper small intestine.

This means that certain digestive conditions can have meaningful consequences for nutrient availability. Celiac disease, for example, can damage the lining of the small intestine and interfere with nutrient absorption, sometimes contributing to iron deficiency even when dietary iron intake appears adequate. Inflammatory bowel disease, pancreatic disorders, and certain gastrointestinal surgeries can also affect nutritional status.

Medications may play a role as well. Long-term use of acid-suppressing medications can interfere with the absorption of some nutrients in certain circumstances, while metformin use is associated with an increased risk of vitamin B12 deficiency.

For people experiencing persistent digestive symptoms, unexplained nutrient deficiencies, or repeated difficulty maintaining adequate nutrient levels, it’s worth investigating whether an underlying digestive or medical issue may be contributing.

For everyone else, supporting digestive health often begins with the fundamentals: eating a varied diet, consuming adequate fiber and fluids, moving regularly, and addressing persistent gastrointestinal symptoms rather than simply adding more supplements.

The gut microbiome also participates in nutrient metabolism, including the fermentation of certain fibers and production of metabolites that interact with intestinal tissues. However, the relationship between microbiome composition and human nutrient absorption is complex, and we don’t currently have evidence that achieving a particular microbiome test result will reliably improve vitamin or mineral status.

A healthy digestive system is an important foundation for nutritional adequacy, but not every digestive concern requires a specialized test or supplement protocol.

03Understand your individual needs instead of supplementing blindly

Perhaps the most important strategy is recognizing that nutrient requirements aren’t identical for everyone.

A woman preparing for pregnancy has different nutritional needs from a growing toddler. Someone who follows a vegan diet may need particular attention to vitamin B12. A person with heavy menstrual bleeding may be at greater risk for depleted iron stores, while someone with a history of gastrointestinal surgery may require specialized nutritional monitoring.

Even within the same stage of life, individual needs can vary based on genetics, medical history, medications, dietary patterns, and other factors.

This is where thoughtful laboratory testing can be particularly useful. When there is a meaningful reason to investigate nutritional status, testing can help identify deficiencies, evaluate the response to treatment, and guide appropriate supplementation.

But choosing the right tests matters. Ferritin is useful for evaluating iron stores, although inflammation can affect its interpretation. Vitamin B12 can be assessed through blood testing, sometimes alongside additional markers when results are unclear. Other nutrients are more difficult to evaluate accurately, and routine testing may not be necessary or clinically useful.

The goal isn’t to test every nutrient in the body. It’s to identify questions worth answering and use the most appropriate tools to answer them.

And when supplementation is needed, more isn’t always better. Certain nutrients compete for absorption, some have relatively narrow safety margins, and excessive doses can interfere with normal physiology. High-dose zinc, for example, can contribute to copper deficiency over time, while excessive iron intake can cause gastrointestinal side effects and may be harmful in certain circumstances.

Sometimes the most meaningful intervention is adding a specific nutrient. Other times, it’s adjusting the timing of a supplement, changing the formulation, treating an underlying medical condition, or recognizing that additional supplementation isn’t necessary.

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Individualized nutrition is about providing the right support for the right person, not giving everyone the longest possible supplement list.

What nutrient testing can tell us, and what it can’t

As much as we love laboratory testing, it’s important to understand that nutritional status is more complex than a collection of blood values.

Some nutrient measurements provide useful information about body stores or functional status, while others primarily reflect recent intake or are influenced by inflammation, hydration, and other physiological factors. Blood concentrations don’t always tell us exactly what’s happening inside every cell or tissue, and not every nutrient has a validated laboratory marker that can guide supplementation.

This means nutrient testing works best when combined with a thoughtful review of dietary intake, symptoms, growth or developmental history, medications, and relevant medical conditions.

It’s also worth remembering that the relationship between nutrients and health isn’t always linear. Moving from deficiency to adequacy can provide meaningful benefits, but increasing intake beyond what the body needs doesn’t necessarily produce additional improvements.

This distinction is particularly important during pregnancy and childhood, when both deficiency and excess can have consequences.

At Parenthood Wellness, we see nutritional testing as a tool for understanding the body’s story. It can help us identify areas that deserve attention, guide individualized recommendations, and evaluate whether those changes are having the intended effect.

But the goal is never to create a perfectly optimized laboratory report. It’s to use meaningful information to support real health.

The bigger picture

One of the things I find most exciting about nutrition is how something so small can influence processes that are so important.

A few hundred micrograms of folic acid before conception can reduce the risk of serious birth defects. Adequate iodine supports the thyroid hormones involved in fetal brain development. Iron helps deliver oxygen and supports neurological development during pregnancy and childhood. Calcium and vitamin D contribute to the bone mass that children will carry into adulthood.

These aren’t abstract benefits. They’re examples of how nutritional adequacy supports the actual biological processes through which our bodies grow, develop, and function.

And because our nutritional needs change throughout life, understanding where we stand can be incredibly valuable. Sometimes that means focusing on nutrient-dense foods. Sometimes it means improving absorption, identifying an underlying digestive issue, or using targeted supplementation to address a documented deficiency.

We can’t control every health outcome through nutrition, and taking more supplements won’t automatically produce better results. Genetics, environment, medical conditions, and countless other factors will always influence health.

But we do have opportunities to support the body’s nutritional needs during some of its most important developmental windows.

At Parenthood Wellness, that’s why we’re so passionate about nutrient testing and individualized nutrition. We want to understand what the body needs, make use of modern tools when they offer meaningful information, and help families build strong nutritional foundations from preconception through pregnancy and childhood.

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Because sometimes, changing the course of health begins with something as simple as identifying what’s missing, and making sure the body has what it needs to thrive.