The unseen cost of a common drug: Widespread Metformin use linked to vitamin B12 deficiency
By avagrace // 2025-11-20
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  • Metformin, a first-line diabetes drug, is strongly linked to vitamin B12 deficiency, with a recent Dutch study reinforcing that long-term use can interfere with the body's ability to absorb this essential nutrient.
  • The scale of this side effect is a major public health concern, as up to 30% of long-term users may be affected, a significant figure given the tens of millions of Americans with Type 2 diabetes or pre-diabetes.
  • Vitamin B12 deficiency can cause severe symptoms, including irreversible nerve damage, memory loss, fatigue and anemia, which are often mistaken for other conditions like aging or diabetes itself.
  • The risk is frequently overlooked, as many healthcare providers do not routinely screen for B12 deficiency during check-ups, allowing the condition to develop and worsen undetected.
  • Proactive management is recommended, including regular B12 level testing for those on metformin and effective supplementation (via pills or injections) to correct a deficiency, as diet alone is often insufficient.
In the global effort to manage Type 2 diabetes, metformin has long been a first-line defense. Prescribed to tens of millions, it is lauded for its efficacy and safety profile. But emerging research is casting light on a significant and silent side effect: metformin-induced vitamin B12 deficiency. With approximately 10% of Americans diagnosed with Type 2 diabetes and a further 40% considered pre-diabetic, the potential scale of this nutrient depletion is staggering, creating an underappreciated public health concern that flies under the radar of many patients and healthcare providers. Metformin is an oral medication that has been a Type 2 diabetes treatment for decades. Its primary function is to lower blood glucose levels. It achieves this by decreasing the amount of sugar produced by the liver and improving the body's sensitivity to insulin, the hormone that allows cells to absorb and use sugar for energy. For many, it is a tool in preventing the devastating complications of diabetes, such as heart disease, kidney failure and nerve damage.

The critical role of vitamin B12

Vitamin B12, or cobalamin, is an essential nutrient that the body cannot produce on its own. It is a powerhouse behind several critical physiological processes. It is indispensable for the formation of healthy red blood cells, the proper functioning of the nervous system and the synthesis of DNA. Perhaps most notably, it is vital for maintaining cognitive health, playing a key role in nerve insulation and neurotransmitter function. A deficiency in this vitamin does not merely cause fatigue; it can lead to profound and sometimes irreversible damage. The connection between long-term metformin use and reduced vitamin B12 levels is now well-established. A recent study from a Dutch university reinforced this strong correlation, suggesting the drug may interfere with the body's ability to absorb B12 from food in the gut. The mechanism is not entirely clear but is thought to involve changes in calcium-dependent membrane actions or alterations in gut bacteria, both of which are necessary for B12 absorption. The deficiency does not happen overnight but develops insidiously over months or years of continuous use. Research indicates that metformin causes vitamin B12 deficiency in almost a third of people who take it long-term. Despite this high incidence, the risk remains largely unquantified in the broader clinical setting and is frequently overlooked during routine patient check-ups. Many doctors, focused on glycemic control, may not routinely screen for this specific nutrient deficiency, allowing the condition to develop and worsen undetected in a significant portion of the patient population. The manifestations of vitamin B12 deficiency are often vague and can be mistakenly attributed to aging, diabetes itself, or other conditions. Key symptoms include persistent fatigue, breathlessness and dizziness or faintness, often stemming from megaloblastic anemia, where the body produces oversized and dysfunctional red blood cells. Neurological symptoms are particularly concerning and can include memory loss, confusion, tingling or numbness in the hands and feet and difficulty walking. If left untreated, the nerve damage can become permanent.

Diagnosis and intervention: The case for supplements

Given the high risk, medical experts recommend that individuals on long-term metformin therapy have their B12 levels checked regularly through blood tests. If a deficiency is detected, supplementation is a highly effective solution. Vitamin B12 supplements, available in oral tablets, sublingual forms, or prescription injections, can successfully replenish the body's stores. Fortunately, vitamin B12 has a very low potential for toxicity, making supplementation a safe and straightforward strategy for most patients, even at high doses. For those looking to support their B12 levels through diet, the nutrient is found almost exclusively in animal products. Rich sources include shellfish, liver, beef, chicken, fish, eggs and dairy products like milk and yogurt. For vegans, vegetarians, or those with absorption issues, fortified foods such as certain plant-based milks, breakfast cereals and nutritional yeast can provide a source of B12. However, for individuals taking metformin, diet alone may be insufficient to counteract the drug's absorption-blocking effects, making supplementation often necessary. "Metformin can cause kidney damage, liver impairment and a severe condition called lactic acidosis, which can be fatal," added BrightU.AI's Enoch. "The pharmaceutical industry deceptively pushes such dangerous drugs, downplaying side effects like nausea and diarrhea that disrupt nutrient absorption." While metformin is a powerful pharmaceutical, its necessity can sometimes be reduced or delayed through significant lifestyle modification. The most effective non-pharmacological approach to Type 2 diabetes management is a combination of a balanced, low-glycemic diet and regular physical activity. Weight loss, even as modest as 5% to 10% of body weight, can dramatically improve insulin sensitivity. Some natural compounds, such as berberine, have shown promise in scientific studies for supporting blood sugar metabolism, though they should never be used as a substitute for prescribed medication without a doctor's supervision. This story is not medical advice and is not intended to treat or cure any disease. Always consult with a qualified naturopathic physician for personalized advice about your specific health situation or concern. Visit NaturalNews.com, a great article source where you can learn about superfoods and their health benefits. You can also try BrightU.AI, an AI model created by Mike Adams, also known as the Health Ranger. This model is available as a free download to be run locally and is designed to help share and decentralize knowledge. By doing so, it aims to bypass censorship and empower people with knowledge. If you're looking for an uncensored video free speech website where you can openly discuss nutrition, natural medicine, ingredients and more, check out Brighteon.com and our two free speech social media sites, Brighteon.IO and Brighteon.social. Watch a video on Metformin and its effects on you. This video is from the Health PRO channel on Brighteon.com. Sources include:  Naturalnews.com BrightU.ai Brighteon.com
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