Dr. Vliet’s Health Tip: Low Energy, Fatigue, and Brain Fog? It Isn’t Just Your Thyroid!

Don’t listen to the social media influencers that seem to be blaming everything on the thyroid or cortisol levels. They tell you a story about their symptoms that you completely relate to, sounds just like what you are experiencing. You cannot diagnose from symptoms alone – too many conditions overlap – and you certainly can’t diagnose yourself from videos on YouTube or social media posts!

Today’s health tip focuses on another common and frequently overlooked cause of fatigue, low energy, slowed thinking and “brain fog” –or as one patient said “I feel like my get-up-and-go has gotten up and GONE!”  Yes, it’s quite true that hypothyroidism can cause all those symptoms and more—forgetfulness, constipation, weight gain, dry skin, and cold intolerance.  Yes, it is true that we need to fully assess thyroid function, including thyroid antibodies—which I have done on ALL my patients since I started my private medical practice in 1985.

But these symptoms are not unique to the thyroid, as I have said in most of my books, programs and articles. Vitamin B deficiencies—especially vitamin B12 and folate (B9)—can produce the identical pattern of low stamina, reduced exercise tolerance, poor concentration, memory problems, low mood, mental slowing, loss of energy and motivation to “get up and go.”

A normal thyroid test does not rule out B-vitamin deficiency, just as a low B12 level does not rule out thyroid disease!

The key question is often not “Is this thyroid or B vitamins?” but “Could one—or both—be contributing causes? Are there other metabolic or endocrine causes also contributing to my loss of energy and brain fog?”  A thorough workup for multi-determined symptoms like fatigue and brain fog also needs to include all the tests I have listed in the Treatment Guides on our website, and my books (available through the Truth for Health store at www.Shoptruthforhealth.com (all profits go to support the Foundation.)

Vitamin B12 and folate are necessary for healthy red-blood-cell production, oxygen delivery, DNA synthesis, and normal neurologic function. When deficiency leads to anemia, people may experience weakness, shortness of breath, palpitations, headaches, and profound fatigue. B12 deficiency can also affect the nervous system directly, causing tingling or numbness, impaired balance, memory difficulty, depressed mood, or cognitive slowing—even before anemia appears on a routine blood count. If you have the MTHFR gene, and are not taking methylated B vitamins, you are not likely absorbing enough of the B vitamins even if you take supplements. Simple blood tests can be checked to see if you have one of these MTHFR mutations that affect vitamin and mineral absorption, and I do this for my patients routinely.

Make sure your physicians or other health professional doing lab tests for you does NOT stop with just thyroid tests when you have the symptoms I described above. This is particularly important for adults over 60, people using metformin or long-term acid-suppressing medications, those following vegan or highly restrictive diets, and people with gastrointestinal disease, bariatric surgery, or autoimmune conditions.   A full-spectrum, methylated B-complex can help restore nutritional adequacy and improve symptoms when a true deficiency or gap in your intake exists, but it is not a substitute for an accurate diagnosis. Testing helps identify the specific deficiency, guides the appropriate dose and form of treatment, and prevents a potentially important problem—particularly B12-related nerve injury—from being overlooked or masked by indiscriminate supplementation without knowing what your root causes are.

“Diagnostics” are a critical step in the evaluation of anything that isn’t working as it should –whether it’s your car, your computer, your kitchen appliances OR your body!  That’s such a common-sense starting point. Yet sadly, my medical profession today seems to be also bypassing that basic step and making “diagnoses” based on symptoms and writing a prescription for a pill—often an antidepressant to “improve energy.” All too often, however, the culprit isn’t “depression” causing low energy – it is more likely a result of nutritional and vitamin deficits, metabolic disruption, and/or endocrine (hormone) imbalance.  To sort out these questions and decide the right treatment approaches, it is critical to get the right blood tests at the beginning, along with physical checks and imaging studies to augment the diagnosis.
For today’s Health Tip, I just wanted to focus on one of the most overlooked blood test panels that has a major impact on our energy level, mood, metabolism and clarity of thinking – our “mental sharpness.”  I am not going to talk about today ALL the blood tests I think are important in a comprehensive evaluation for a new patient (check my more extensive list in my COVID Vaccine Injury Treatment Guide on our website). I want to focus today on the B vitamins because they are so often overlooked.

Since COVID hit and the COVID shots rolled out, I have been seeing far more vitamin deficiencies in my patients because these are blood tests that I regularly do on my new patients and for follow up appointments. I think the uptick in vitamin deficits are related to the COVID shot causing spike-protein-induced and toxic lipid-nanoparticle-induced inflammatory damage to the GI tract and blood vessels, which in turn impairs nutrient absorption and delivery to tissues.  As a result of the marked increase in number and type of vitamin deficits I see in my patients, I have expanded my recommendations on vitamin supplementation.

For many years I have routinely checked B12, folate, and B6 vitamin levels since these play a major role in the common symptoms of fatigue, PMS, depression, memory loss that often lead to doctors overprescribing anti-depressants. True deficiencies of other B vitamins have not been as common in the United States since many foods are fortified with these vitamins. But with the COVID rollout and increases damage we are seeing from the COVID injections, I am seeing more deficiencies of all the B vitamins in my patients.  So I have expanded the B vitamin panel and now check those levels in all my new patients and those established patients who have gotten COVID shots and boosters. Even minor deficits can manifest in vague symptoms and affect quality of life.

There is another major point most doctors and social media influencers don’t know to tell you.  Lab reference ranges are just that: a RANGE.  It doesn’t tell you what is optimal for you! “Normal” for one person may be too low for someone else.  Each of us is different, and have different metabolic needs.  There are also optimal ranges based on clinical studies and this is often not discussed with patients, who are often just told “Your results are in the normal range, you are find.”  For example, I recently ordered a complete vitamin B panel on an active mid-fifties woman who described a decline in exercise performance and lack of “get up and go” she used to have. Her estradiol, testosterone and thyroid labs were all in the optimal range on her Rx.  But labs came back with a vitamin B1 (thiamine) deficiency, despite a healthy balanced diet and lifestyle.  Thiamine deficits play a huge role in central nervous system function and our cellular energy production.

I recommended she start our methylated TruB Complex Full Spectrum with an added thiamine supplement, in addition to her B12 she was already taking (due to her mostly vegetarian diet). Within a few weeks she reported significant improvements, including “increased motivation to exercise and more enjoyment from her activities!”  Based on diet alone, we did not expect to see such a significant thiamine deficiency. It was only the blood test that made it possible to identify.  I suspect it was one of the many adverse effects (including elevated D-Dimer) from her earlier COVID injections.

I also know the power of vitamin Bs from my own experience (and perhaps this has made me even more aware to do comprehensive checks for all my patients). Last summer, as I wrote in an earlier health tip, a rattlesnake killed my last three egg-laying chickens, and I lost my fresh eggs, which had become my main daily source of B vitamins.  My chickens had been fine two hours earlier when I let them out to roam, and I came back find all three were lying on the ground dead!  No signs of injury, and they had plenty of water, food and shade. The only clues we had as to what happened was the rapid death of all three, markedly abnormal dark purplish skin discoloration (a sign of snake venom poisoning), and I knew rattlesnakes, common in the AZ desert, eat chicken eggs and go after chickens as prey.

When I began raising chickens in 2022, I had so many fresh eggs I would normally eat 4 or even 5 fresh eggs a day over my three meals, since eggs are one of the healthiest and nutrition dense foods available – and a rich source of quality protein, healthy fat, choline, omega-3 fatty acids, lutein and B vitamins—all major supporters of energy and brain health. The B vitamins are also essential support for energy metabolism, nerve health and red blood cell formation. Just a note to reassure our readers: even eating all those eggs every day, my cholesterol never went up, I have a very healthy lipid profile (cholesterol 140-150), and I taking no medication except my thyroid and estradiol (which naturally lowers total cholesterol, lowers LDL and increases HDL). It is another false “narrative” that “eggs increase cholesterol,” and we shouldn’t eat them. That lie that caused people to avoid a healthy source of critical nutrients, AND served Big Pharma profit agenda of pushing people to take statins to “lower cholesterol.”

When my egg-laying chickens were killed, I simply did without eating eggs every day since I didn’t like the taste of store-bought eggs. My own eggs from my chickens tasted MUCH better! My chickens didn’t have any antibiotics or growth hormones, and I fed my chickens with organic feed, dried mealworms, vegetables, organic greens, watermelon and berries.  I also didn’t feel like eating much meat in the extremely hot summer months, which is another good source of all the B vitamins.  Gradually over the summer and early fall, I began feeling more tired, not as “sharp” in focus, and felt like my mojo was dragging, and I had more nerve tingling in my hands.  I just thought it was the extreme and prolonged heat wave we had in southern AZ last summer.  Although I was still taking our Multivitamin with B vitamins and iron, I didn’t really think about the major loss of choline, omega-3 fatty acids, lutein and all the B vitamins because I no longer had my eggs every day, and wasn’t eating much meat either.

Finally I had an AHA! Moment.  When it dawned on me I wasn’t eating my own chicken eggs every day, I decided to add our TruB Full Spectrum, Complete Methylated B Complex in addition to the low dose of B vitamins in my multivitamin.  After about two weeks, I was surprised to see that I could really tell a difference in how I felt. I wasn’t as “draggy” tired, back closer to my usual energy, and had more “get up and go” ( I call it “mojo”).  I felt my mental acuity was sharper, back to normal in focus and concentration.  I have to admit I was surprised to find that the simple addition of the Methylated B Complex made such a difference so quickly when I thought I had a pretty healthy regimen already.  My daily intake of my great healthy chicken eggs had obviously been more of a loss than I realized.

I have generally recommended a B complex to my patients, usually as part of a quality multivitamin every day. In patients with the MTHFR mutations, which I also check, I may also prescribe injectable weekly B12 shots if levels are low, since MTHFR mutations cause impaired oral absorption of B12 and a few other nutrients. But, I am now seeing that the B vitamins in multivitamins are not always enough.   Most doctors today do not check vitamin blood tests, but you can order these tests yourself on line from many laboratories including Quest Diagnostics and Lab Corp who offer the services for patients to directly order for themselves many common blood tests.  I have always said that you should never diagnose from symptoms alone and doctors should never discount a patient’s concerns because of how they look. It is just too simple and easy to get the tests done and know for sure exactly what you are dealing with. Look at all the different functions in your body that the various B vitamins are involved in. It’s pretty amazing and explains why B vitamins are SO important!  This is WHY I test all of the B vitamins.

B VITAMINS WORK BEST in COMBINATION, SYNERGISTICALLY
I don’t generally recommend taking large doses of single B vitamins without taking the foundation of a balanced B complex, preferably a methylated form if using oral supplements.  Taking a single B vitamin supplementation can mask other deficiencies. I find that many people have multiple subclinical deficits that benefit from comprehensive support.

That is why I test first, then supplement with a multivitamin with a B complex or a separate methylated Full Spectrum B Complex and then add single vitamin B supplementation as indicated by the objective lab tests.

Early Indicators for B Vitamin Deficiencies

B vitamin deficits, even just suboptimal levels, can have a wide range of clinical presentations, from subtle early signs to severe neurological, psychological, metabolic, and hematologic (blood) manifestations.

• Neurological Indicators: Peripheral neuropathy symptoms are classic presentations of deficits in for B vitamins.  Presence of numbness, tingling, reduced sensation, “pins and needles in feet, hands, face or tinnitus should be indications for comprehensive lab testing of all the B vitamin levels.  All of these symptoms indicate possible nerve damage due to inadequate levels of one or more B vitamins.  Other symptoms and signs include balance difficulties, loss of fine motor coordination, and gait abnormalities (ataxia). On physicial exam, doctors may find decreased or absent deep tendon reflexes, muscle weakness, and muscle wasting in the extremities.  All of these are neurological “red flags.”  If your doctor dismisses the need for blood tests of your vitamin levels, you should order those tests yourself or consult another physician.
• Cognitive, Mood and Psychological Indicators: Memory problems, confusion, difficulty concentrating, or cognitive decline justify testing for B12, folate, thiamine (B1), B2 and B6 deficits. Mood and behavioral changes include depression, irritability, anxiety, restless legs during sleep, nightmares, insomnia. In severe cases, people may have delirium, dementia, hallucinations, or altered mental status. In people who drink alcohol heavily, Wernicke’s encephalopathy triad of confusion, ataxia, and ocular abnormalities occurs from severe alcohol-induced thiamine deficiency.  It requires urgent evaluation with lab tests, physical and neurological exam, and even brain imaging studies.
• Hematologic Indicators: Macrocytic anemia or megaloblastic changes on complete blood count suggest B12 or folate deficiency. Symptoms of anemia including unexplainable fatigue, weakness, pallor, shortness of breath, and palpitations. Elevated mean corpuscular volume (MCV >100 fL) is a supportive finding, though not highly sensitive for functional deficiency.
• Dermatologic and Oral Manifestations: Glossitis (inflamed, smooth, shiny, or sore tongue) is a characteristic finding in B12, B2, and B3 deficiencies. Mouth ulcers or angular cheilitis (cracks at the corners of the mouth) suggest B vitamin deficiency, particularly B2, B6, or B12. For biotin deficiency, look for a scaly red rash around the eyes, nose, mouth, and genital area, along with hair loss (alopecia) or brittle nails and hair.
• Cardiovascular Symptoms: Heart palpitations, arrhythmias, tachycardia, or signs of congestive heart failure (particularly shortness of breath when upright, or lying flat, and peripheral edema – swelling in the limbs) suggest wet beriberi from thiamine deficiency.
• Constitutional and Gastrointestinal Symptoms: Persistent unexplained fatigue or weakness, especially when combined with other symptoms, is a common presentation. Unintentional weight loss and decreased appetite are early indicators, particularly for thiamine and B12 deficiency. Nausea, vomiting, diarrhea, abdominal discomfort, or digestive disturbances can accompany deficiency states.
• Vision Changes: Deficits in B vitamins can cause blurred vision, difficulty with night vision, or loss of visual acuity even when glasses prescriptions are properly corrected.  B vitamin testing, particularly B12 and thiamine, should be part of a thorough eye exam when these problems occur.
• High-Risk Populations: High-risk patient groups for B vitamin deficits include chronic alcohol use, malabsorption disorders, strict vegetarian/vegan diets (B12), advanced age, prolonged total parenteral nutrition without supplementation, bariatric surgery, chronic kidney or liver disease, pregnancy, and certain medications (discussed below).  Blood testing for vitamin levels should definitely be done for these groups, even without overt symptoms, since the deficits can cause subtle problems and early treatment helps prevent permanent damage.

Medications that Interfere with B Vitamin Absorption

A variety of medications interfere with B vitamin absorption via multiple mechanisms: reducing stomach acid production, disrupting gut microbiota, increasing urinary excretion, and altering metabolic pathways. The effects are often dose- and duration-dependent, and can lead to deficits that you don’t realize are happening, yet may be quietly robbing you of energy, vitality and mental acuity.

• Gastic Acid Suppression: Proton pump inhibitors (PPIs) and H2 receptor antagonists (examples: omeprazole, lansoprazole, esomeprazole, ranitidine, cimetidine, and famotidine) reduce gastric acid production, which significantly reduces B vitamin absorption, especially in people with MTHFR mutations that impair oral absorption of crucial B vitamins to begin with. Stomach acid is essential for releasing B vitamins from protein-bound food sources through proper protein digestion. Losing these protein-bound food sources due to less stomach acid production is especially serious for B12 and folate from foods. These medications primarily affect protein-bound food sources of B vitamins, but don’t have that unwanted problem with B vitamins from supplements since vitamin supplements are not bound up in proteins.
• Disruption of Gut Microorganism Balance: Antibiotics have a huge impact to decrease all the B vitamins (B1, B2, B3, B6, B7, B12, and folate) because antibiotics destroy beneficial intestinal bacteria essential for B vitamin synthesis and absorption. Gut bacteria  naturally produce biotin (B7) and assists in absorbing other B vitamins. Borad-spectrum antibiotics, such as aminoglycosides, cephalosporins, fluoroquinolones, macrolides, penicillins, sulfonamides, and tetracyclines, all create B vitamin deficiencies through “friendly fire” damage to the beneficial bacteria. That’s why after a course of antibiotic treatment I recommend a two-week replenishment course of our high-potency, multi-species TruProBiotic Complex, then follow that with our TruProBiotic Daily.
• Increased Urinary Excretion: Both loop diuretics and thiazide diuretics enhance urine production to eliminate salt and water from the body, which means they also increase excretion of water-soluble B vitamins, particularly thiamine (B1) and B6. Anyone taking a diuretic for any length of time should have all the B vitamin levels tested and consider taking a full spectrum B complex supplement.
• Interference with Intestinal Absorption: Metformin is a common medicine for insulin resistance and diabetes that reduces B12 and folate absorption in the intestine through multiple mechanisms, including direct interference with intrinsic factor-B12 receptor complexes and calcium-dependent membrane processes. The effect is dose- and duration-dependent, with studies showing progressive B12 deficits over years of treatment.  I have a lot of patients taking metformin and I always check B vitamin levels and recommend full spectrum B complex supplements. Colchicine impairs B12 absorption by affecting the intrinsic factor-vitamin B12 receptor in the gut. Anti-convulsant medications (phenytoin, carbamazepine, barbiturates, valproic acid) reduce folate absorption from foods and increase biotin excretion, increasing risk of deficits that contribute to depression, low energy, memory loss and weight gain.
• Metabolic and Hormonal Disruption: Oral contraceptives and hormone replacement therapy reduce B2, B3, B6, B12, and folate through mechanisms that remain incompletely understood. That is why I routinely do blood tests of the B vitamins and recommend supplementation with a good quality multivitamin with optimal doses of the components of a balanced B vitamin formula for all my patients taking oral contraceptives or HRT.
• Anti-Inflammatory Drug Effects: Non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and naproxen hinder folate absorption, particularly at high doses used in arthritis pain control, rather than routine doses for intermittent pain and inflammation. Corticosteroids also reduce levels of multiple B vitamins.

Impact of Alcohol and Caffeine on B Vitamin Bioavailability

Both alcohol and caffeine significantly reduce B vitamin bioavailability through different mechanisms.  These effects occur even at moderate consumption levels. The impact is dose-dependent and can compound existing deficiencies in those already at-risk for deficiencies.

• Alcohol’s Impact on B Vitamin Status: Alcohol interferes with B vitamin bioavailability through multiple pathways affecting absorption, metabolism, and excretion. Even moderate alcohol consumption (1-2 drinks per day, or 5% of daily calories) significantly decreases B vitamin levels, with one study showing B12 levels dropping in volunteers consuming this small amount daily. The effects are markedly  worse with chronic heavy drinking.
• Caffeine’s Impact on B Vitamin Status: Caffeine acts as a diuretic to increase urination, which decreases blood concentrations of water soluble B vitamins and vitamin C through increased urinary excretion. The effect is dose-dependent. A study of healthy men and women found that coffee consumption was dose-dependently associated with reduced plasma B vitamin concentrations. Individuals drinking 4 or more cups of coffee per day had 11.7% lower folate, 14.1% lower pyridoxal phosphate (active B6), and 5.5% lower riboflavin (B2) concentrations compared to coffee abstainers. Homocysteine concentrations were 6.8% higher in heavy coffee drinkers, with the decrease in folate explaining approximately half of this homocysteine increase. Over time without adequate dietary sources or supplements, increased urination contributes to lower B vitamin levels.

Long-term Health Risks of Vitamin B Deficiency

Long-term vitamin B deficiency poses serious and potentially irreversible health risks affecting multiple body systems.  Some complications become permanent if treatment is delayed. The severity of long-term consequences depends on which B vitamin is deficient, the degree of deficiency, and duration of deficiency before treatment is started.

Here are some examples of long-term health risks of vitamin B deficiency:

• Irreversible Neurological Damage: peripheral neuropathy (lasting numbness and tingling in hands and feet), degeneration of spinal cord, decreased coordination, vision problems. Extended B vitamin deficiency can cause erectile dysfunction, loss of bowel and urinary continence, paralysis, loss of taste and smell.  Severe deficiency can lead to deep depression, memory loss, paranoia, delusions, hallucinations, and loss of deep tendon reflexes.
• Cognitive Decline and Dementia: memory loss, word processing difficulties, confusion, difficulty in thinking, judgment, and reasoning.
• Cardiovascular Complications: elevated homocysteine levels, severe anemia that causes the heart to work harder and leading to abnormally fast heartbeat (tachycardia), angina and even heart failure in later stages of deficiency.
• Cancer Risk: Long-term B12 deficiency caused by pernicious anemia increases the risk of developing stomach or intestinal cancer. Folate deficiency has been shown to increase the risk of colon cancer and appears correlated with onset of other cancers.
• Pregnancy and Fetal Complications: Both B12 and folate deficiencies can cause infertility, making it difficult to become pregnant, although this is typically improved with appropriate supplementation. During pregnancy, inadequate B12 or folate significantly increases the risk of serious birth defects, including spina bifida (improper spinal development), anencephaly (absence of parts of the brain and skull), and encephalocele (brain tissue protruding through skull defects). Folate deficiency also increases risks of premature birth (before 37 weeks), low birth weight, placental abruption, and developmental delays in children.
• Severe Deficiency Diseases: Prolonged thiamine (B1) deficiency leads to beriberi disease, which presents in two forms: wet beriberi affecting the cardiovascular system with heart failure symptoms, and dry beriberi causing neurological damage and muscle weakness. Severe niacin (B3) deficiency causes pellagra, characterized by dermatitis, diarrhea, dementia, and potentially death if untreated. These classic deficiency diseases show the severity of long-term B vitamin depletion, though we rarely see these severe problems now in developed Western countries with better dietary variety.
• Hematologic Consequences: Chronic B12 or folate deficiency results in megaloblastic anemia with production of abnormally large, dysfunctional red blood cells that are less able to carry oxygen. Pernicious anemia (PA) from B12 deficiency occurs when the immune system attacks stomach cells, preventing intrinsic factor production necessary for B12 absorption. Untreated anemia long-term causes chronic fatigue, weakness, shortness of breath, and increased susceptibility to infections, and heart failure in late stages. PA can also increase risk of other autoimmune disorders, including Type 1 Diabetes,
• Other Long-Term Complications: Extended B vitamin deficiency can cause increased systemic inflammation and oxidative damage affecting the immune system. Elevated homocysteine from B vitamin deficiency can impact immune function and cause increased inflammatory responses.

Reversibility and Treatment Response

Early detection and treatment are critical, as many complications become irreversible with prolonged deficiency. If deficit is mild and caught early, patients may respond quickly to medication and dietary modifications. However, those with chronic low B12 levels due to MTHFR mutations, ongoing medications that impair absorption, or underlying health conditions causing deficiency may require lifelong supplementation. Getting the proper blood tests done to help you identify deficits early and then initiate appropriate treatment before permanent damage occurs is the key to preventing long-term complications!

Dr. Vliet’s Recommendations:

I always try out any new product before I recommend it to my patients or put it in my charitable foundation’s store. As I was digging into the best B Complex supplements to recommend out of thousands of products out there, I found the methylated B Complex, TruB™ Full Spectrum, that I added to our store a couple years ago. With my own experience and what I am seeing in my patients who have added our premium B complex, I am confident that most people will benefit from a full spectrum methylated B complex over basic B complex supplements or just supplementing single B vitamins in isolation.