What IBS, Vitamin D Deficiency & Diabetes Reveal About Brain Health
Many of us think of brain health as something we worry about later, when we start forgetting names or misplacing keys. But new research suggests that the earliest signs of Alzheimer’s and Parkinson’s may show up years before any memory lapses do—and in places you might not expect.
A new study published in Science Advances1 analyzed health data from over 20,000 people and found that certain common conditions—including gut issues, low vitamin D levels, and metabolic problems—were linked to a higher risk of developing neurodegenerative diseases up to 15 years before diagnosis.
It’s a striking reminder that brain health doesn’t exist in isolation; it’s deeply connected to how the rest of our body functions. And the good news? That means there’s a long window of opportunity to protect your brain before symptoms ever appear.
How early warning signs were uncovered
To uncover these patterns, researchers looked at 155 different health conditions across thousands of adults. They then tracked which of those individuals went on to develop Alzheimer’s or Parkinson’s disease. When they compared the data, distinct patterns began to emerge—revealing that the earliest clues to brain decline may appear far beyond the brain itself.
Gut issues may signal higher brain risk
People with functional intestinal disorders, things like irritable bowel syndrome (IBS), gastritis, and other chronic gut issues, had significantly higher odds of developing Alzheimer’s or Parkinson’s later on.
These associations appeared more than a decade before diagnosis, suggesting that the gut-brain connection may play a critical role in how these diseases develop over time.
Vitamin deficiencies raise red flags, too
The researchers also identified a link between vitamin deficiencies, especially vitamin D and B vitamins, and an increased risk of Parkinson’s disease. Both of these nutrients are vital for nerve health and protecting the brain from oxidative stress, which can contribute to neurodegeneration.
Metabolic health matters
Beyond gut and nutrient factors, the study found that metabolic and endocrine disorders, such as diabetes and pancreatic issues, were also associated with a greater likelihood of developing Alzheimer’s or Parkinson’s. These conditions can influence insulin signaling and inflammation, both of which affect how the brain ages.
While this research can’t prove that these conditions cause neurodegeneration, it does point to shared biological pathways: inflammation, oxidative stress, and impaired metabolic signaling—all of which can impact the brain long before cognitive symptoms arise.
Strengthening your body to protect your brain
The most empowering takeaway from this research is timing. If these warning signs appear 10 to 15 years before a diagnosis, that means we have a long head start to support the systems that influence brain health. Here’s where to start:
Take your gut health seriously
The gut-brain axis is a two-way communication highway. Chronic gut inflammation and imbalanced microbiota can influence brain function, so paying attention to persistent digestive issues is key. Focus on a fiber-rich diet, fermented foods like yogurt or kimchi, and limit ultra-processed foods that disrupt the microbiome.
Check your vitamin D & B levels
Both vitamin D and B vitamins (especially B12 and folate) support nerve function and protect against oxidative stress. Regular blood testing can catch deficiencies early, and supplementing can make a meaningful difference. Spending time outdoors and eating foods like salmon, eggs, and leafy greens can also help maintain optimal levels naturally.
Prioritize metabolic balance
Conditions like insulin resistance and diabetes can quietly affect brain health. Maintaining stable blood sugar through balanced meals, regular exercise, and sufficient sleep can help protect both metabolic and cognitive function over the long term.
Address inflammation early
Chronic, low-grade inflammation is a common thread connecting many of these conditions. Building daily anti-inflammatory habits—like strength training, managing stress, and eating omega-3-rich foods—can go a long way in keeping both your brain and body resilient.
The takeaway
It’s easy to think of neurodegenerative diseases as inevitable or solely genetic, but this study paints a far more hopeful picture. Many of the early risk factors, like gut health, vitamin status, and metabolic function, are modifiable.
Our bodies are constantly sending signals about what’s going on beneath the surface. Paying attention to them (and supporting whole-body health long before symptoms appear) might just be one of the most powerful ways to protect your brain for decades to come.