A new study suggests that eating more acid-producing foods may increase the risk of depression and anxiety, especially in women.
Here are the key facts:
- Women with high dietary acid load had 21% higher odds of severe depression compared to those with low acid load.
- People with high dietary acid load had 13% higher odds of severe anxiety than those with low acid load.
- High acid foods include processed meats, cheese, eggs and grains. Low acid foods include fruits, vegetables, fish and nuts.
Source: BMC Psychiatry 2023 Sep 18
What is Dietary Acid Load?
When we eat foods, they can have either an acidic or alkaline effect on our body after being metabolized.
Some foods create acid while others create alkali (base).
Dietary acid load refers to how acid-forming or alkaline-forming a food or diet is.
It is determined by calculating the potential renal acid load (PRAL) or net endogenous acid production (NEAP) of the diet.
Foods that increase acid load are generally high in protein, phosphorus, chloride and sulfur, like meats, grains, dairy and processed foods.
Foods that decrease acid load are fruits and vegetables which are high in magnesium, potassium and bicarbonate.
Measuring Dietary Acid Load
Researchers use different scores to estimate the dietary acid load of a person’s diet:
- Potential Renal Acid Load (PRAL) – calculates acid load based on intakes of protein, phosphorus, potassium, magnesium and calcium. Positive PRAL = more acidic. Negative PRAL = more alkaline.
- Dietary Acid Load (DAL) – calculates PRAL and also accounts for body size.
Higher PRAL and DAL scores indicate a more acidic diet, while lower (more negative) scores indicate a more alkaline diet.
Acid-Base Balance & General Health
Our normal blood pH is slightly alkaline, between 7.35-7.45.
The body has multiple systems that tightly regulate acid-base balance.
When acid intake is higher than alkaline intake, the body uses its buffers like bone mineral content, protein stores and respiration to neutralize the extra acid and maintain optimal pH.
Over time, a persistently high acid load can make it difficult for the body to maintain this delicate balance leading to mild metabolic acidosis.
This has been linked to increased risk of chronic diseases like osteoporosis, kidney stones, hypertension and cardiovascular disease.
Acid-Base Balance & Depression
Emerging research now suggests that acid-base balance may also impact mental health.
Studies have linked increased acid load to higher risks of depression, anxiety and psychological distress, while plant-based alkaline diets appear protective.
Potential mechanisms include:
- Inflammation – High acid diets increase inflammatory markers while alkaline diets reduce inflammation. Chronic inflammation is closely tied to mental health disorders.
- Oxidative stress – Acidosis creates an oxidative environment in the body. Oxidative stress damages neurons in brain regions linked to mood regulation.
- Neurotransmitters – Acid-base balance affects production of mood-influencing neurotransmitters like serotonin, dopamine and GABA.
- Hormones – Acidosis impacts stress hormones like cortisol. Elevated cortisol is strongly associated with depression and anxiety.
- Nerve signaling – Acid-sensing ion channels involved in nerve signaling are sensitive to pH changes and linked to depressive behaviors.
- Gut microbiota – An acidic environment alters gut bacteria linked to production of mood-regulating metabolites.
- Nutrient deficiency – Acidosis increases loss of nutrients like magnesium, zinc and B vitamins needed for mental health.
Key Findings on Dietary Acid Load & Depression/Anxiety
This recent study aimed to evaluate the relationship between dietary acid load and severity of depression and anxiety in over 6500 Iranian adults aged 35-65 years.
Researchers calculated participant’s dietary acid load using PRAL and DAL scores based on 3-day food records.
Depression and anxiety severity were assessed using validated questionnaires.
Findings from the research:
- Women with the highest dietary acid load had 21% higher odds of more severe depression compared to women with the lowest acid load.
- The association remained significant even after adjusting for BMI, fiber intake, physical activity and other factors.
- There was no significant association between dietary acid load and depression severity in men.
- For anxiety, people with the highest dietary acid load had 13% greater odds of more severe anxiety than those with the lowest acid load.
- This relationship was significant for the whole study population.
Again, there was no significant link between dietary acid load and anxiety severity when men and women were analyzed separately.
Participants with higher dietary acid loads consumed more grains, meats, protein and phosphorus.
Those with lower acid loads ate more fruits, vegetables, fiber and potassium.
Overall, the findings suggest that higher dietary acid load is associated with worse mental health, especially depression in women and anxiety in the overall population.
How to Reduce Dietary Acid Load
Here are some tips to reduce dietary acid load for better health:
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Eat more fruits and vegetables
Fruits and veggies are rich in minerals like magnesium and potassium that help neutralize acids. Shoot for at least 4-5 servings per day. Great choices are citrus fruits, leafy greens, cucumbers, celery and berries.
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Choose plant proteins
Swap animal proteins like beef and processed meats for plant proteins like beans, lentils, nuts and seeds. They generate less acid.
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Replace refined grains with whole grains
Choose whole grains like barley, quinoa, oats and brown rice instead of simple carbs like white rice and flour products.
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Limit cheese and processed foods
Cheese, processed snacks, fast food and ready-to-eat convenience foods are all highly acidic.
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Drink alkaline water
Skip the sodas and energy drinks which are highly acidic. Hydrate with alkaline water instead. You can use pH drops to make regular water alkaline.
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Don’t overload protein
Moderate your protein portions and aim for 0.8-1g per kg body weight based on activity levels. Excess protein increases acid production.
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Use more herbs and spices
Season your food with fresh herbs, garlic, onions, turmeric and ginger instead of salt. They enhance flavor while reducing acidity.
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Exercise regularly
Being active helps your body efficiently process acids and maintain acid-base balance. Aim for 30-60 mins daily.
What can we learn from this study re: dietary acid & depression/anxiety?
Emerging evidence suggests that dietary acid load may impact risk of depression and anxiety.
Eating more fruits, vegetables, plant proteins and whole grains while limiting processed foods and animal proteins can help reduce dietary acid load for optimal mental wellbeing.
More research is still needed to confirm the acid-base balance theory of mood disorders.
In the meantime, striving for an overall balanced diet based on whole foods seems to be sound advice for both physical and mental health.
References
- Study: Dietary acid load, depression, and anxiety
- Authors: Hossein Bahari et al. (2023)
