How Dietary Intervention Lifts Depression

How Dietary Intervention Lifts Depression by Dr. Joseph Mercola for Mercola

Foods have an immense impact on your body and your brain, and eating whole foods as described in my nutrition plan is a good way to simultaneously support your mental and physical health. Avoiding sugar and artificial sweeteners is in my view, based on the evidence, a crucial aspect of preventing and/or treating depression.

Both contribute to chronic inflammation and can wreak havoc with your brain function. Recent research also shows how swapping processed junk food for a healthier diet can significantly improve depression symptoms, which really shouldn’t come as a great surprise.

The Sugar Trap

Research^1,2 published in 2014 linked sweetened beverages — both sugar- and artificially-sweetened beverages — with an increased risk of depression. Those who drank more than four cans or glasses of soda had a 30% higher risk of depression compared to those who did not consume sweetened beverages of any kind.dep

Interestingly, fruit juices were even more hazardous. The same amount of sweetened fruit drinks (four glasses) was associated with a 38% higher risk of depression.

Overall, artificially sweetened so-called “diet” drinks were associated with the highest risks of depression, compared to beverages sweetened with sugar or high-fructose corn syrup. More specifically, compared to those who did not drink sweetened beverages:

• Those who drank primarily diet soda were 31% more likely to suffer with depression, whereas regular soda was associated with a 22% increased risk
• Those who drank primarily diet fruit drinks had a 51% higher risk for depression, while consuming regular fruit drinks was associated with a more modest 8% increased risk
• Drinking primarily diet iced tea was associated with a 25% increased risk for depression, whereas those who drank regular sweetened iced tea actually had a 6% reduced risk

Similarly, recent research³ detailed in “The Link Between Fast Food and Teenage Depression” found adolescents who had elevated levels of sodium and low levels of potassium in their urine — two factors indicative of a diet high in junk food and processed food — had more frequent symptoms of depression.

According to the authors,⁴ “Given the substantial brain development that occurs during adolescence, individuals in this developmental period may be particularly vulnerable to the effects of diet on the neural mechanisms underlying emotion regulation and depression.”

Why Sugar Takes a Toll on Mental Health

There are at least four potential mechanisms through which refined sugar intake could exert a toxic effect on mental health:

1. Sugar (particularly fructose) and grains contribute to insulin and leptin resistance and impaired signaling, which play a significant role in your mental health
2. Sugar suppresses activity of a key growth hormone called brain derived neurotrophic factor (BDNF), which promotes healthy brain neurons. BDNF levels are critically low in both depression and schizophrenia, which animal models suggest might actually be causative
3. Sugar consumption also triggers a cascade of chemical reactions in your body that promote chronic inflammation. In the long term, inflammation disrupts the normal functioning of your immune system, which is linked to a greater risk of depression⁵
4. Sugar impairs the microbiome and its influence on the modulation of stress response, immune function, neurotransmission and neurogenesis

In 2004, British psychiatric researcher Malcolm Peet published a provocative cross-cultural analysis⁶ of the relationship between diet and mental illness. His primary finding was a strong link between high sugar consumption and the risk of both depression and schizophrenia. According to Peet:

“A higher national dietary intake of refined sugar and dairy products predicted a worse 2-year outcome of schizophrenia. A high national prevalence of depression was predicted by a low dietary intake of fish and seafood.

The dietary predictors of … prevalence of depression are similar to those that predict illnesses such as coronary heart disease and diabetes, which are more common in people with mental health problems and in which nutritional approaches are widely recommended.”

One of the key predictors of heart disease and diabetes is in fact chronic inflammation which, as Peet mentions, is also associated with poor mental health. Sugar is a primary driver of chronic inflammation in your body, so consuming excessive amounts of sugar can truly set off an avalanche of negative health events — both mental and physical.

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