As the days get shorter and the calendar fills with end-of-year commitments, it can be easy to explain away feeling run-down. Low energy gets attributed to a busy schedule, and changes in sleep, meals, or exercise become things we’ll address after the holidays. Yet fall can be a useful time to pause and take stock of your health before those demands build.
Part of that check-in involves noticing how you feel and what has changed. Another sometimes more motivating action may involve taking the plunge to get some blood work done. Blood tests can add information about nutrient status, blood sugar regulation, and inflammation, which helps you identify areas that deserve attention, allowing you to make more informed decisions about your health.
There are obviously many biomarkers that can offer insight into your health. Here, we’ll focus on five worth checking in on as the seasons change, cold and flu season approaches, and the holidays return. Identifying nutrient gaps or other areas that need attention now gives you an opportunity to address them, support your energy, and head into the coming months more resilient and prepared for the fourth quarter!
You might not be surprised that vitamin D deserves attention as we head into the cooler months. Our skin produces vitamin D in response to UVB exposure, and that production varies with the season, latitude, and time spent outdoors. While you may have gotten a boost from summer sunshine, that does not necessarily mean your levels will remain adequate throughout winter.
Vitamin D supports calcium absorption, bone health, muscle function, and immune regulation. Its connection to respiratory health is particularly relevant this time of year: a prospective observational study following 198 healthy adults during fall and winter found that vitamin D levels of at least 38 ng/mL were associated with approximately half the risk of developing an acute respiratory tract infection compared with lower levels. Participants with those higher levels also experienced fewer days of illness.1 These findings highlight the relevance of vitamin D status as we enter the colder months. The blood test used to assess your status is 25-hydroxyvitamin D, which reflects contributions from sunlight, food, and supplements.
If you have a history of low vitamin D or a condition that affects its absorption, fall can be a useful time to discuss testing with your clinician. Reviewing a result alongside your current intake can help determine whether your plan needs adjusting. The goal is to address inadequate status and support normal function as the seasons change. For a closer look at sunlight, food sources, and supplementation, see our recent article, Don’t Wait Until Winter to Think About Vitamin D.
If you’re heading into fall already feeling depleted, it may be worth checking your iron status. Ferritin is a protein that stores iron, making it a useful indicator of your body’s iron reserves. Iron is needed to produce hemoglobin, the protein in red blood cells that carries oxygen throughout the body. Low iron stores can cause, contribute to, or worsen fatigue, even before anemia develops.
A randomized controlled trial published in CMAJ studied 198 menstruating women with unexplained fatigue, normal hemoglobin, and ferritin below 50 ng/mL. After 12 weeks, fatigue scores decreased by approximately 48% in the iron-treatment group, compared with 29% in the placebo group.2 These findings highlight that low iron stores significantly impact energy levels making ferritin a useful marker to assess when someone feels persistently tired.
This is especially relevant for women with heavy menstrual periods, low dietary iron intake, or difficulty absorbing nutrients. Identifying depleted stores now provides an opportunity to investigate the cause and address it before the busiest months of the year.
It is important to be aware that ferritin can rise with inflammation, so a higher result does not always mean iron stores are sufficient or excessive. Your clinician can consider it alongside your complete blood count and, when needed, additional iron studies to determine whether dietary changes, supplementation, or further evaluation would be appropriate.
Vitamin B12 is essential for healthy red blood cell formation, DNA production, and nervous system function. When levels are inadequate, symptoms can include fatigue, weakness, difficulty concentrating, or tingling in the hands and feet. As the year gets busier, persistent changes in energy or concentration deserve attention rather than being dismissed as another consequence of a full calendar.
One reason B12 is worth checking is that eating enough does not always mean absorbing enough. It occurs naturally in animal foods, making vegetarians and vegans more vulnerable to inadequate intake without fortified foods or supplements.3 However, older adults, people with certain digestive conditions, those taking metformin, or long-term acid-suppressing medications can also be at risk. The NIH Office of Dietary Supplements notes that B12 deficiency can cause neurological symptoms even without anemia, making early identification important.
A serum B12 test is a useful starting point. If a result is borderline or symptoms suggest deficiency, your clinician may order an additional testing to help clarify whether B12 availability is inadequate. Reviewing your result alongside your diet, medications, and digestive history helps determine the appropriate next step. Addressing a deficiency can support the blood and nerve functions that contribute to everyday well-being.
Fall often brings changes in how we eat and move, from fewer evening walks to more celebrations centered around food. Checking in on blood sugar regulation can help you establish a starting point and identify habits worth prioritizing through the coming months.
Hemoglobin A1c, or HbA1c, reflects your average blood sugar over approximately three months. It measures the percentage of hemoglobin with glucose attached, offering a longer-term view than a single fasting glucose measurement.
In a study published in the New England Journal of Medicine, researchers followed more than 11,000 adults without a history of diabetes or cardiovascular disease. Higher A1c levels were associated with a greater risk of developing diabetes and cardiovascular disease, even after accounting for fasting glucose.4 This makes A1c useful for understanding long-term risk as well as assessing current blood sugar regulation.
Comparing your result with previous measurements adds another layer of helpful information. A sustained upward trend can prompt a closer look at eating patterns, activity, sleep, and other factors affecting metabolic health, even if your A1c falls within a ‘normal’ range.
Inflammation is part of how the body responds to infection and repairs injured tissue. When that response persists, however, it can contribute to damage over time. High-sensitivity C-reactive protein, or hs-CRP, measures small amounts of a protein produced by the liver in response to inflammation. This makes it useful for detecting low-grade inflammatory activity that may otherwise go unnoticed.
One of its strongest applications is understanding long-term cardiovascular risk. A study published in the New England Journal of Medicine followed nearly 28,000 initially healthy women for 30 years. Women in the highest hs-CRP group had approximately 70% greater relative risk of a major cardiovascular event than those in the lowest group, after adjustment for other risk factors.5 Assessing inflammation alongside cholesterol-related markers provided a more complete picture of risk, illustrating why preventive care often benefits from looking beyond the standard cholesterol panel.
For a fall health check-in, the aim is to understand your baseline and identify persistent patterns worth addressing. Timing is especially relevant as respiratory illnesses become more common: a cold or another acute infection can temporarily raise CRP. Testing when you feel well, and repeating an unexpectedly elevated result when appropriate, helps distinguish a temporary immune response from ongoing inflammation.
If hs-CRP remains elevated, your clinician can consider possible contributors alongside your symptoms, medical history, and other lab findings. The result can guide further evaluation and a discussion of practical steps, including regular physical activity, dietary habits, and treatment of underlying conditions. These approaches can help reduce inflammation while supporting broader health goals.
Heading into the holidays, this gives you an opportunity to choose a few priorities you can sustain through a busy season, with follow-up to assess how your health responds.
These five biomarkers offer useful starting points, but their greatest value comes from understanding how they fit together. Your symptoms, medical history, medications, and previous results all help determine what a finding means and whether it deserves further attention.
We’ve already seen how these connections matter: iron status can influence the interpretation of A1c, and inflammation can affect ferritin. Looking across several markers helps clarify patterns that might be missed when each result is considered separately. It also helps distinguish a finding that needs follow-up from one that may reflect a temporary change.
That broader perspective is built into the VitOS Blueprint, a comprehensive baseline assessment combining more than 50 biomarkers with a detailed review of your health history, symptoms, lifestyle, and goals. It includes all five markers discussed here, alongside additional measures of cardiovascular and metabolic health, thyroid function, nutrient status, liver and kidney health, and a complete blood count.
Your findings are brought together in a personalized VitOS Roadmap, including a system-by-system breakdown, a practitioner video walkthrough, and recommendations to help you prioritize your next steps. You can put those recommendations into practice independently or choose a VitOS membership for ongoing support.
Fall is a practical time to begin that process. Understanding where you are now can help you address concerns, establish supportive routines, and enter the coming months with a clearer plan for your health.
Explore the VitOS Blueprint to learn more about the assessment and your personalized roadmap.
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