According to the World Health Organization, depression is now the leading cause of ill health and disability worldwide,^1,2 affecting an estimated 322 million people globally, including more than 16 million Americans, 6 million of which are seniors.³ Statistics also reveal we're not being particularly effective when it comes to prevention and treatment. Worldwide, rates of depression increased by 18 percent between 2005 and 2015.⁴

If you or someone you love is struggling with depression or some other mental health problem, remember that your diet is a foundational aspect that must not be overlooked. As noted in a 2015 study⁵ published in the medical journal Lancet:

"Although the determinants of mental health are complex, the emerging and compelling evidence for nutrition as a crucial factor in the high prevalence and incidence of mental disorders, suggests that diet is as important to psychiatry as it is to cardiology, endocrinology and gastroenterology."

The Compelling Link Between Food and Mood

Recent research^6,7,8 looking at the effects of the antihypertensive DASH diet on mental health concluded this kind of dietary pattern, which is low in sugar and high in fresh fruits and vegetables, can help reduce the risk of depression in seniors. Overall, people who followed the DASH diet were 11 percent less likely to develop depression over the following six years, whereas those following a standard Western diet, high in red meat and low in fruits and vegetables, had the highest rates of depression.

It's worth noting that while many conventional experts recommend the DASH diet, it is not necessarily ideal for optimal health, as it also promotes whole grains and low-fat foods, including low-fat dairy. Healthy fats, including saturated animal and plant fats and animal-based omega-3, are quite crucial for optimal brain health. I believe the reason the DASH diet produces many beneficial results is because it is low in sugar and high in unprocessed foods — not because it's low in fat.

Other studies have shown that unprocessed foods, especially fermented foods, help optimize your gut microbiome, thereby supporting optimal mental health,^9,10 whereas sugar, wheat (gluten) and processed foods have been linked to a greater risk for depression, anxiety and even suicide. The primary information highway between your gut and your brain is your vagus nerve, which connects the two organs.¹¹

Your gut also communicates to your brain via the endocrine system in the stress pathway (the hypothalamus, pituitary and adrenal axis), and by producing mood-boosting neurotransmitters like serotonin, dopamine and gamma-aminobutyric acid or GABA. These communication links help explain why your gut health has such a significant impact on your mental health.

The Strong Link Between Sugar and Depression

A number of food ingredients can cause or aggravate depression, but one of the most significant is sugar, particularly refined sugar and processed fructose.¹² For example, in one study, men consuming more than 67 grams of sugar per day were 23 percent more likely to develop anxiety or depression over the course of five years compared to those whose sugar consumption was less than 40 grams per day (which is still far higher than the 25 grams per day recommended for optimal health).¹³

This held true even after accounting for other contributing factors, such as socioeconomic status, exercise, alcohol use, smoking, other eating habits, body weight and general physical health. Lead author Anika Knüppel,¹⁴ a research student in the department of epidemiology and public health at University College London, commented on the findings, saying:¹⁵

"Sweet food has been found to induce positive feelings in the short-term. People experiencing low mood may eat sugary foods in the hope of alleviating negative feelings. Our study suggests a high intake of sugary foods is more likely to have the opposite effect on mental health in the long-term."

Research¹⁶ published in 2002, which correlated per capita consumption of sugar with prevalence of major depression in six countries, also found "a highly significant correlation between sugar consumption and the annual rate of depression." A Spanish study¹⁷ published in 2011 linked depression specifically to consumption of baked goods.

Those who ate the most baked goods had a 38 percent higher risk of depression than those who ate the least. This makes sense when you consider baked goods contain both processed grains and added sugars.