Multiple studies are now confirming that increasing consumption of fruits and vegetables can significantly boost our thinking skills, help prevent memory loss and help stave off depression. Some of these studies are quite large, and the findings are clear.
Let’s take a look at the evidence. This will reveal just how much fruits and vegetables we have to eat to make a difference, and even some of the more effective foods.
Better eating Europeans have better cognitive health
A 2019 cognitive health study from Germany’s Charite’ University1 tested 22,635 adults from 11 countries around Europe. The study began in 2011 and all participants were tested for their diets. They were also tested for short- and long-term memory, depression, quality of life, mobility and other criteria indicating their general physical and mental well-being.
The researchers found that those who ate more fruits and vegetables had significantly better cognitive and mental health.
The scientists concluded:
“Frequent consumption of fruits and vegetables is associated with improved health outcomes, including cognitive and mental health.”
Fruits and vegetables boost thinking and memory
In a 2019 diet study from Harvard University,2 researchers analyzed 20 years of diet data on 28,000 male health professionals. The men had completed diet questionnaires every four years regarding what they were eating. The study began when the men were 51 years old on average. Within the last four years of the end of the study, they were tested on their thinking and memory skills.
Those who ate the most fruits and vegetables in the years before the thinking questions had the best thinking and memory skills.
The researchers also found that those who ate six or more servings a day of vegetables had a 34 percent less likelihood of developing poor thinking and memory during the 20 years compared to those who ate two servings of veggies.
Orange juice was a surprise winner in this study. The researchers found those who drank more orange juice had a 47 percent less chance of developing poor thinking and memory compared to those who drank less than one serving of orange juice per month. This is consistent with other research finding that citrus boosts cognition.
Large study connects depression to diet
Researchers from the University of Leeds in the U.K. and the U.K.’s University of York3 analyzed and followed about 50,000 people in the United Kingdom over a period of 8 years (from 2009 to 2017).
The researchers questioned each person about the amount of fruits and vegetables they ate a day. They also conducted annual visits along with either a survey or home interview to determine the mental well-being and extent of any psychiatric disorders among the volunteers.
The researchers amassed weekly vegetable and fruit consumption reporting and compared this with moods and psychiatric profiles of the subjects. They scaled a mental well-being rating for each along with a life satisfaction rating for each subject.
The data concluded that well-being and life satisfaction levels were dramatically higher among those who ate more fruits and vegetables. Those who ate fruits every day had more than three times the life satisfaction levels than those who ate fruits from one to three days each week. Those who ate vegetables every day had over 70 percent higher levels of life satisfaction compared to those who ate veggies one to three days a week.
As for mental well-being, those who ate fruit every day had over double the levels of mental well-being scores compared to eating fruits for between one and three days. And eating vegetables daily resulted in about triple the scores of mental well-being compared to those who ate vegetables for between one and three days.
The researchers also found that increasing fruit and vegetable consumption significantly boosted moods and life satisfaction levels among those studied. For example, increasing vegetable consumption from never to four to six times a week boosted moods and life satisfaction to levels seen in getting married.
They also found that increasing the frequency of fruit and vegetable consumption significantly had a life satisfaction equivalent of an unemployed person finding a job.
Raw fruits and vegetables boost mental well-being
In a 2018 mental health study from New Zealand’s University of Otago4, researchers tested 422 adults between 18 and 25 years old. The study tested their mental health symptoms, which included depressive symptoms, anxiety, negative or positive moods, and life satisfaction.
After the researchers controlled for other possible causes, the researchers found that those who consumed more raw fruits and vegetables had reduced symptoms of depression. They also had better moods, and less anxiety and greater life satisfaction.
The researchers did not see the same association with processed fruits and vegetables.
Here are the top ten raw foods associated with reduced depression and better mental health in this study:
• Dark leafy greens
• Citrus fruits
• Fresh berries
The researchers concluded:
“Raw fruits and vegetable intake, but not processed fruit and vegetable intake, significantly predicted higher mental health outcomes when controlling for the covariates. Applications include recommending the consumption of raw fruits and vegetables to maximize mental health benefits.”
Short diet change can reduce depression
A change in the diet doesn’t necessarily require eating more fruits and vegetables for many years. Diet changes can also affect young people in a short period of time.
A 2019 diet-depression study from Australia’s Macquarie University5 tested 101 adults between 17 and 35 years old who had symptoms of depression. Using the Australian Guide to Healthy Eating, the researchers had half of the subjects eat a diet consisting of more fruits and vegetables, and other components of the Mediterranean Diet.
After only three weeks, the researchers followed up with the subjects. They found that those who increased their fruit and vegetable consumption had significantly fewer symptoms of depression compared to the control group, maintained their habitual diet.
Previous studies confirm these findings
In a 2014 review of research, scientists from the UK’s University of Reading6 reviewed the findings of previous research on fruits and veggies and cognition. The researchers found that 17 of 19 large population studies found that a steady diet with more fruits, vegetables and juices resulted in better cognitive health among healthy adults.
The research also found three intervention (changing the diet) studies found that fruits and vegetables boost mental well-being. They also found that drinking 100% fruit juices resulted in better cognition.
Mental well-being connected to diet nutrients
In a 2019 study from the University of Manchester,7 led by Dr. Joseph Firth, led a study that analyzed 16 studies that totaled 45,826 volunteers. The researchers found that improving one’s diet and the nutritional quality of the diet with respect to more fruits and vegetables significantly decreased symptoms of depression. Diets with more nutrition also boosted mental well-being – established also in the University of Leeds study above.
The research also established that a general boost in dietary quality – rather than special diets – can benefit the person in terms of moods and depression, according to Dr. Firth:
“The similar effects from any type of dietary improvement suggests that highly-specific or specialized diets are unnecessary for the average individual.”
Study co-author Dr Brendon Stubbs, who also teaches at the King’s College London, concluded the results by stating:
“Our data add to the growing evidence to support lifestyle interventions as an important approach to tackle low mood and depression.”
The study also found that benefits of diet improvement affected women in a more broad way compared to men. This is consistent with other research finding that a woman’s body tends to be more sensitive to nutrients and supplements, and drug side-effects are often greater in women.
Astaxanthan also boosts cognition according to other research.
1. Gehlich KH, Beller J, Lange-Asschenfeldt B, Köcher W, Meinke MC, Lademann J. Consumption of fruits and vegetables: improved physical health, mental health, physical functioning and cognitive health in older adults from 11 European countries. Aging Ment Health. 2019 Feb 7:1-8. doi: 10.1080/13607863.2019.1571011.
2. Yuan C, Fondell E, Bhushan A, Ascherio A, Okereke OI, Grodstein F, Willett WC. Long-term intake of vegetables and fruits and subjective cognitive function in US men. Neurology. 2019 Jan 1;92(1):e63-e75. doi: 10.1212/WNL.0000000000006684.
3. Ocean N, Howley P, Ensor J. Lettuce be happy: A longitudinal UK study on the relationship between fruit and vegetable consumption and well-being. Soc Sci Med. 2018 Dec 31. pii: S0277-9536(18)30690-7. doi: 10.1016/j.socscimed.2018.12.017.
4. Brookie KL, Best GI, Conner TS. Intake of Raw Fruits and Vegetables Is Associated With Better Mental Health Than Intake of Processed Fruits and Vegetables. Front Psychol. 2018 Apr 10;9:487. doi: 10.3389/fpsyg.2018.00487.
5. Francis HM, Stevenson RJ, Chambers JR, Gupta D, Newey B, Lim CK. A brief diet intervention can reduce symptoms of depression in young adults – A randomised controlled trial. PLoS One. 2019 Oct 9;14(10):e0222768. doi: 10.1371/journal.pone.0222768.
6. Lamport DJ, Saunders C, Butler LT, Spencer JP. Fruits, vegetables, 100% juices, and cognitive function. Nutr Rev. 2014 Dec;72(12):774-89. doi: 10.1111/nure.12149.