During an interview this week on the Frankie Boyer show about depression, she asked me what were, in my opinion the top 3 causes of depression-my response diet, stress and physical inactivity. Diet plays a significant role in our brain function. Dietary factors should always be addressed when managing depression, as evidence demonstrates that various aspects of diet can affect the disorder.
We know that countries which have the highest fish consumption experience much lower rates of depression. Japan is the prime example.
Did you know that not only nutritional deficiencies, but certain foods contribute to the development of depression? One study found that fast foods play a role, while another determined soft drink consumption does the same.
A 2012 study shows how eating fast food is linked to a greater risk of suffering from depression. It was headed by scientists from the University of Las Palmas de Gran Canaria and the University of Granada (in Spain), eating commercial baked goods (fairy cakes, croissants, doughnuts, etc.) and fast food (hamburgers, hotdogs and pizza) is linked to depression.
Published in the Public Health Nutrition journal, the results reveal that consumers of fast food, compared to those who eat little or none, are 51% more likely to develop depression.
Furthermore, a dose-response relationship was observed. In other words this means that “the more fast food you consume, the greater the risk of depression,” explains Almudena Sánchez-Villegas, lead author of the study.
Most fast food meals are accompanied by a soda drink, which is another risk factor for depression.The study involved 263,925 people between the ages of 50 and 71 at enrollment. From 1995 to 1996, consumption of drinks such as soda, tea, fruit punch and coffee was evaluated. About 10 years later, researchers asked the participants whether they had been diagnosed with depression since the year 2000. A total of 11,311 depression diagnoses were made.
The American Diet- Modern Nutritional Disaster?
Japanese have the lowest rates of depression in the developed world. Compared to the US, we have rates approximately 30 times higher!
According to Dr. Joseph R. Hibbeln, senior clinical investigator at the National Institute of Alcohol Abuse & Alcoholism, who believes that the imbalance between omega 3 and omega 6 fatty acids in the American diet is “a modern nutritional disaster”!
He states this imbalance not only contributes to depression, but also dyslexia, hyperactivity (ADD, ADHD), and violent behavior.
Omega 3 fatty acids are prevalent in fish, and to a lesser degree in plants nuts, seeds, etc., are consumed in low amounts in the standard American diet. While omega 6 fatty acids that are more prevalent in vegetable oils, especially soy bean. Between 1909 and 1999, the production of soybean oil for food consumption has risen 1000 times, and is part of almost every fried or processed food Americans eat.
According to Dr. Hilbein, “This now means that, on average 20 percent of all calories in the U.S. diet come from one food source: soybean oil. That means that about 10 percent of all calories in the U.S.diet come from one molecular species: linoleic acid.
“Cell membranes ‘stuffed’ with omega 6 fatty acids are associated with inflammation and almost every negative physical and mental health outcome one can name: heart disease, diabetes, mental disorders of all kinds.”
Conversely, cell membranes abundant with omega 3 fatty acids are associated with better health, lowered rates of depression, diabetes and heart disease, prison violence, even murder.
Individuals with depression may consume too many inflammatory omega-6 fatty acids and saturated fats, so increasing consumption of omega-3’s and decreasing consumption of trans-fats, saturated fat, and excess omega-6 fatty acids is recommended.
Omega-3 fatty acids and folate (a B vitamin) both appear to be very important in mood management. Although the role of these nutrients in the diet is important, one should augment the diet with supplements as described below for maximum benefit in addressing symptoms of depression or in trying to prevent a recurrence. As described later in this protocol, omega-3 fatty acids have been shown to decrease susceptibility to depression and may help as an adjuvant therapy. Foods high in omega-3’s include deep-water fish such as salmon, mackerel, sardines, and tuna, as well as flax seeds, and some nuts (e.g., walnuts).
Sugar & Insulin
Evidence suggests that limiting sugar intake to control blood sugar levels is another important approach to depression. This would include addressing hyperglycemia (high blood sugar), hypoglycemia (low blood sugar), or reactive hypoglycemia (low blood sugar that occurs within 4 hours of eating). Reactive hypoglycemia may be more common in people who are not overweight. To address high or low blood sugar, it is important to limit or avoid sugar and refined carbohydrates, eat small meals 4–6 times per day, eat a balance of healthy proteins, fats, and complex carbohydrates, and decrease caffeine. The nutrients magnesium and chromium and practicing relaxation techniques also help manage hypoglycemia.
Soda Pop Consumption
People who drank more than four cans or cups per day of soda were 30 percent more likely to develop depression than those who drank no soda. Those who drank four cans of fruit punch per day were about 38 percent more likely to develop depression than those who did not drink sweetened drinks. People who drank four cups of coffee per day were about 10 percent less likely to develop depression than those who drank no coffee. The risk appeared to be greater for people who drank diet than regular soda, diet than regular fruit punches and for diet than regular iced tea.
“Our research suggests that cutting out or down on sweetened diet drinks or replacing them with unsweetened coffee may naturally help lower your depression risk,” said Chen. “More research is needed to confirm these findings, and people with depression should continue to take depression medications prescribed by their doctors.”
Healthy Diets that Prevent Depression
Evidence also suggests that an anti-inflammatory Mediterranean Diet may help prevent or manage depression. A Mediterranean diet, which is rich in omega-3 fatty acids and polyphenolic antioxidants, could serve as a foundation to which targeted dietary supplements are added for maximum response. The diet generally includes good quantities of fish, vegetables, unrefined grains, beans or legumes, fruit, and olive oil. It includes moderate amounts of dairy (mostly cheese and yogurt) and red wine, and limits meats to small portions. Also, a 2012 British study found eating 7 or 8 servings of fresh fruits and vegetables daily improved mood functioning.
As noted in part 1 of this series folate (also known as vitamin B9) and B12 deficiencies are linked to depression, other mood disorders, and physical diseases.
In particular strict vegetarians and vegans have been found to have low levels of B12, due to avoidance of meat and dairy products, which contain the highest amounts of vitamin B 12. Some researchers are now recommending considering folate and B12 supplementation as a part of the treatment regimen for depression. A recent study also suggests that high vitamin B12 status may be associated with better treatment outcome. Folate and vitamin B12 are major determinants of one-carbon metabolism, in which S-adenosylmethionine (SAM-e) is formed. SAM-e donates methyl groups that are crucial for neurological function. Increased plasma homocysteine is a functional marker of both folate and vitamin B12 deficiency.
Increased homocysteine levels are found in depressive patients, as well as those with heart disease, and Alzheimer’s. In a large population study from Norway increased plasma homocysteine was associated with increased risk of depression but not anxiety.
There is now substantial evidence of a common decrease in serum/red blood cell folate, serum vitamin B12 and an increase in plasma homocysteine in depression.
Vitamin D also plays a major role in brain functioning. Lower levels are known to occur during winter months, and play a role in the development of Seasonal Affective Disorder (winter depression). There are a number of good research studies from the last few years that look specifically at vitamin D and depression.
In a review of research about vitamin D and depression in 2013, researchers looked for and analyzed all of the published research about depression and vitamin D up until February 2011. They looked at good quality research studies that explored whether:
• a lack of vitamin D in your blood is linked with being depressed
• a lack of vitamin D in your blood makes it more likely you will develop depression
• taking a vitamin D supplement can improve or prevents depression
The researchers found more than 5000 research articles, however just 13 explored this area effectively. More than 31000 people participated in these 13 studies. The results revealed a relationship between low levels of vitamin D in the blood and depression.
However, the research didn’t show whether vitamin D was the cause or effect of depression.
A 2008 research study from Norway found that people with a low level of vitamin D in their blood had more symptoms of depression. This research also found that taking vitamin D, particularly in large amounts, improved the symptoms of depression. The biggest effect occurred in those with the most severe symptoms.
However, this research only looked at people that were overweight, so it’s not possible to say whether the results would be similar for everyone. All of the participants also took a calcium supplement, and the researchers suggest that this could have affected the results, for example it could be vitamin D and calcium working together, rather than vitamin D on its own, that effects depression.
A second research study from Norway looked at whether the symptoms of depression were related to vitamin D blood levels. The study also looked at whether taking a vitamin D supplement affected the symptoms of depression in people that had low vitamin D levels. The results showed that:
• low levels of vitamin D in the body are linked to the symptoms of depression
• when people with low vitamin D levels took a supplement, it improved their vitamin D levels, but had no effect on their symptoms of depression
• low vitamin D levels could be the result, rather than the cause of depression
Although this study used a good amount of vitamin D supplement, it lasted for only six months. The researchers suggest that because depression is a condition that tends to develop slowly and last a long time, a longer study might have shown different results. Those who took part also had either no symptoms of depression or very mild symptoms, and this may have influenced the results.
Vitamin D and depression in women
A study published in 2012 from researchers in the United States showed that there was no difference in depression symptoms between those women who took vitamin D and those women who took placebos.
The study looked at a very large group of women and was the first study of this kind to do so. The researchers suggest that the amount of vitamin D that the women took may have been too small to have an effect on the symptoms of depression. The participants taking vitamin D also took a calcium supplement, and the researchers suggest that this could have affected the results.
For example it could be vitamin D and calcium together, rather than vitamin D on its own, that effects depression.
Another study from 2012 showed that taking vitamin D supplements had no effect on depression in older women. The women in the study took either a vitamin D supplement, or hormone therapy, or both together. Researchers also took blood samples to see whether there was a link between the symptoms of depression and vitamin D receptors on the cells of the body. No link was found.
This was a large, good quality research study which ran for a long time (three years). However, the researchers suggest that there may not have been enough women with depression who also had very low levels of vitamin D taking part, and this may have affected the results.
The most recent 2014 meta-analysis found: Vitamin D supplementation may be effective for reducing depressive symptoms in patients with clinically significant depression; however, further high-quality research is needed.
Key Vitamin D Research Findings
• Research does seem to show a link between low levels of vitamin D in the blood and symptoms of depression.
• Research hasn’t yet shown clearly whether low vitamin D levels cause depression, or whether low vitamin D levels develop because someone is depressed.
• Lack of vitamin D may be one of many factors that contribute to a depressed mood. There may be many other things that cause depression, which means it’s difficult to say for certain that when depression improves it is vitamin D that is causing the improvement.
• The effects of vitamin D on depression may take a long time to work, years for example. This means that research carried out over short periods of time may not show any impact of vitamin D on depression.
• People who have depression go outdoors less, so they are less likely to have good amounts of vitamin D in their blood.
• Some researchers have suggested that giving vitamin D supplements may work for depression when someone has very low levels of vitamin D to begin with. Taking a vitamin D supplement may work less well for people who already have good vitamin D levels.
• Taking vitamin D may only have a role to play if you’re already depressed.5
Intestinal Tract & Depression
The digestive tract and the brain are crucially linked, according to mounting evidence showing that diet and gut bacteria are able to influence our behavior, thoughts and mood. Now researchers have found evidence of “leaky gut,” among people with depression.
Normally the digestive system is surrounded by an impermeable wall of cells. Certain behaviors and medical conditions can compromise this wall, allowing toxic substances and bacteria to enter the bloodstream. In a study published in the May 2013 issue of Acta Psychiatrica Scandinavica, approximately 35 percent of depressed participants showed signs of leaky gut, based on blood tests.
The researchers don’t know precisely how leaky gut relates to depression, but preceding work offers some clues. Displaced bacteria can activate autoimmune responses and inflammation, which are known to be associated with the onset of depression, lower mood and fatigue. “Leaky gut may maintain increased inflammation in depressed patients,” which could exacerbate the symptoms of depression if not treated, says Michael Maes, a research psychiatrist with affiliations in Australia and Thailand and an author of the paper.
We also know that the intestinal tract has an impact on our mental state, as a result of the strains of predominant bacteria it contains
The consumption of fermented foods may be particularly relevant to the emerging research linking traditional dietary practices and positive mental health. The extent to which traditional dietary items may mitigate inflammation and oxidative stress may be controlled, at least to some degree, by bacteria in the intestinal tract. Some researchers now believe that properly controlled fermentation may often amplify the specific nutrient and phytochemical content of foods, the ultimate value of which may associated with mental health; furthermore, we also argue that the microbes (for example, Lactobacillus and Bifidobacteria species) associated with fermented foods may also influence brain health via direct and indirect pathways.
Next week: Evidence based complementary therapies for depression
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Bertone-Johnson E R, Powers S I, Spangler L et al. Vitamin D Supplementation and Depression in the Women’s Health Initiative Calcium and Vitamin D Trial. Am J Epidemiol 2012; 176(1):1-13
Jorde, M. Sneve, Y. Figenschau, J et al. Effects of vitamin D supplementation on symptoms of depression in overweight and obese subjects: randomized double blind trial. J Intern Med. 2008;264(6):599-609
Dean A J, Bellgrove M A, Hall T et al. Effects of vitamin D supplementation on cognitive and emotional functioning in young adults–a randomised controlled trial. PLoS One. 2011;6(11):e25966
Anglin R, Samaan Z, Walter S et al. Vitamin D deficiency and depression in adults: systematic review and meta analysis. British Journal of Psychiatry, 2013.
Yalamanchili V, Gallagher C. Treatment with hormone therapy and calcitrol did not affect depression in older post menopausal women: no interaction with estrogan and vitamin D receptor genotype polymorphisms. Menopause, 2012.