Common Nutrient Deficiencies After Bariatric Surgery
Common Nutrient Deficiencies After Bariatric Surgery
By Nicole Freebairn, Registered Nutritionist
One of the most important aspects of your long-term success after bariatric surgery is keeping your nutrition and blood levels in check. While surgery is a powerful tool for weight loss and improving health, it also significantly changes the way your body absorbs nutrients. This means that even if you're eating well, deficiencies can still develop over time — sometimes without any obvious symptoms at all.
Understanding the most common nutrient deficiencies and how to prevent or manage them is key to feeling your best, protecting long-term health, and avoiding potentially serious complications.
Why Do Nutrient Deficiencies Happen After Surgery?
After surgery, your body doesn’t absorb nutrients from food the same way it used to. These changes can affect:
Stomach acid levels (which help break down food and release nutrients)
Absorption surface area in the stomach (and small intestine for bypass patients)
Appetite and food intake, which are reduced significantly, especially in the first year
These factors make it harder to get adequate vitamins and minerals through food alone — even with a healthy diet.
Five Common Nutrient Deficiencies
1. Iron
Iron is essential for energy, red blood cell production, and oxygen transport throughout the body. It’s one of the most common deficiencies after surgery, especially in menstruating women. That being said, it’s always important to test before supplementing iron as symptoms of deficiency and toxicity can be similar.
Symptoms to watch for:
Fatigue
Pale skin
Shortness of breath
Dizziness or brain fog
2. Vitamin B12
B12 is vital for nerve health, energy, and brain function. B12 deficiency can present very similarly to iron deficiency, as it can also cause a type of anaemia, however if left untreated, the impact of B12 deficiency can be more severe.
Symptoms to watch for:
Tingling or numbness in hands/feet
Mood changes or low mood
Fatigue
Poor memory or focus
3. Calcium and vitamin D
These two work together to maintain strong bones, muscles, and teeth. Without regular supplements, your body may pull calcium from your bones, increasing the risk for osteoporosis.
Symptoms to watch for (often silent early on):
Muscle weakness
Bone pain
Increased fracture risk
Fatigue
4. Thiamine (Vitamin B1)
Particularly common in the first 6 months post op, thiamine deficiency can develop quickly and lead to serious neurological problems — especially if vomiting or poor food intake has been an issue post-op.
Symptoms to watch for:
Nausea
Fatigue
Brain fog
Weakness and coordination problems
5. Vitamin A
Vitamin A plays a role in immune function, skin and eye health, and cell repair. Deficiency is more common after a One-Anastomosis Gastric Bypass (also known as Mini or Loop bypass) as this more significantly impacts the absorption of fat-soluble vitamins such as vitamin A.
Symptoms to watch for:
Dry eyes or night blindness
Poor wound healing
Dry or flaky skin
Increased susceptibility to illness
Why Some Deficiencies Go Unnoticed
Not all nutrient deficiencies show clear signs early on — some may take months or even years to develop noticeable symptoms. That’s why regular blood testing and daily bariatric-specific supplements are essential components of your post-op care.
How to Stay On Top of It
✅ Take your quality supplements daily
Your bariatric supplements are formulated to meet your specific needs — regular over-the-counter multivitamins unfortunately aren’t adequate in many key nutrients, and often contain too much vitamin B6 (which can lead to toxicity). Speak with your team if you’re unsure which products are right for you.
✅ Get regular blood tests
We recommend testing every 6–12 months (more frequently in some cases) to catch changes before they cause problems.
✅ Be honest about how you’re feeling
Unexplained fatigue, mood changes, or new symptoms? Don’t dismiss them — they could be a sign of a nutrient deficiency.
✅ Eat as well as you can, consistently
Focus on eating a variety of nutrient-dense foods, mix up your choices of fruits and vegetables, and include a combination of animal and plant-based proteins where possible.
Final Note
Bariatric surgery is a life-changing tool, but to get the most from it, your body needs the right support. Staying consistent with your supplements is just as important as your food, movement, and mindset habits.
💬 If it’s been a while since your last check-in, now is the perfect time to book a blood review with our nutritionists and ensure your supplements are still appropriate for you. We extend this service to all bariatric patients, even if you had your surgery elsewhere. Reach out to our team via phone: 07 859 0185 or email: reception@tailorclinics.co.nz
🛒 Need to stock up? We carry a range of high-quality, bariatric-specific supplements designed to meet your post-op needs. Browse the collection here.
Disclaimer: this blog post is intended for educational purposes only and does not replace individual medical advice. For more support please always seek the guidance of your relevant health practitioners.