This time of year, when days are short, the Christmas festivities are over and it seems a long time to the summer holidays can cause many people to feel a bit low. As well as making efforts to do things we enjoy and can boost our mood, there are some nutrition and lifestyle factors that may help.
Blood sugar balance
The most important aspect of brain health, and particularly mood is our blood sugar balance: too high or too low blood sugar can affect brain function dramatically. The key to good blood sugar balance, is to prevent the spikes in blood sugar that happen after eating high carbohydrate or high sugar foods. These foods cause our blood sugars to rise dramatically and then, as the body tries to bring these high levels down, a corresponding trough of low blood sugar. Such changes have been shown to affect mood (1). The best way to avoid these problems is to avoid a high carbohydrate diet and always go for slow-release carbs, avoiding refined carbs and sugars. Aim to get your carbs from whole plant foods, including nuts and seeds, root vegetables and perhaps small amounts of higher carb foods such as well-cooked beans.
Some people find that a really low-carb approach is helpful. Certain conditions connected with mood problems have benefited from a very low carb (VLC) diet (2). Intermittent fasting has also shown promise in preserving brain health (3).
It’s important to get enough healthy fat. Low fat intake, particularly of monounsaturated fats (such as olive oil), has been shown to adversely affect mood (4). Some people may be concerned that eating a higher fat diet may affect their cholesterol levels. Cholesterol is a major component in the brain and nervous system. Myelin, which covers nerve axons to help conduct the electrical impulses that make movement, sensation, thinking, learning, and remembering possible, is over one fifth cholesterol by weight. Even though the brain only makes up 2% of the body’s weight, it contains 25% of its cholesterol. Cholesterol is such an important component of the brain that, if we don’t eat enough, the body makes its own. Eating foods high in cholesterol, therefore, are likely to be beneficial to brain health rather than detrimental.
Protein and (some) carbs
Serotonin, a brain hormone connected with mood, is produced from the amino acid tryptophan which is found in animal foods, such as poultry and meat, cheese and dairy, and many plant foods, such as avocados, bananas, walnuts, legumes, tomatoes, sunflower and pumpkin seeds. Having sufficient protein intake will ensure you’re getting enough tryptophan. Tryptophan needs to enter the brain and be converted into serotonin, and studies have found that carbohydrate can help this process. This does not mean you should adopt a high carb diet, but including some carbohydrates may help your brain serotonin levels.
A high nutrient diet
Nutrient-dense foods (i.e., those with lots of vitamins and minerals), like meat, fish, eggs, and vegetables are high in the micronutrients we need to keep our bodies and brains running. Several dietary factors have been found to be important for brain health.
The first of these is the essential omega-3 fatty acid called DHA (docosahexaenoic acid). It’s part of the very structure of our brains and is a critical for brain function. The main source of DHA in our diets is from oily fish and shellfish. Although there are other forms of omega-3 that can be obtained from plants (such as flaxseed), which can then be converted into DHA in the body, the amount that is actually converted into DHA is very low in most people (5).
Vitamin B12 is another vital micronutrient for the brain. Lack of vitamin B12 has been implicated in a variety of neurological and mental illnesses and decline in brain function in ageing (6,7). Good sources are meat and shellfish. Vitamin B12 deficiency is common among elderly people, in those with digestive problems, those who are taking certain medications and it can be especially difficult for vegans (and to some extent vegetarians) to obtain enough B12.
Vitamin B6 (8,9) and folate (9,10) are both important for good brain function and mood, being closely involved in the biochemistry of the brain. Folate is found in dark, leafy greens and in chicken liver primarily, and then in lentils. B6 is found in sunflower seeds, fish, chicken, turkey, beef, and avocados.
Choline (a member of the B vitamin group) has been shown to be important for mood, memory and brain function (11,12). Choline is found mainly in egg yolks and liver, with much, much smaller amounts in other foods.
Deficiency in B vitamins has been associated with raised levels of the amino acid, homocysteine, in the brain which, in turn, is thought to increase the risk of Alzheimer’s disease, low mood and other mental health disorders (13,14).
Vitamin D has been found to be important for mental health, especially as we age (15). Eating oily fish and, most importantly, getting enough sunshine are the best ways of keeping up vitamin D levels.
Lithium is a mineral most often found in drinking water but also in legumes, pistachio nuts and many other vegetables. The main source in our diets is drinking water, and the levels of lithium vary considerably from place to place. Some mineral waters can be very high in lithium. Lithium is well known to help with low moods.
Other important factors
Gut health: researchers are starting to discover a myriad of ways in which gut microbes influence the brain (16). Thus, it’s a good idea to look after your gut health. 90% of the serotonin in our bodies is made in the gut by bacteria in the Bifidobacterium group, which are often found in fermented foods such as yogurt (check the label for which bacteria are included).
Inflammation is well established as a contributory factor in many cases of depression (17,18). Foods that may reduce inflammation might, therefore, also help depression and this could be one of the ways in which omega-3 fats from oily fish work.
Getting outdoors and walking: studies show that physical activity outdoors can boost mental health (19). Serotonin, a neurotransmitter in the brain which strongly affects our mood, tends to decrease when light levels are low. Bright light such as is experienced from being outdoors has been shown to boost serotonin levels and is often used to treat seasonal affective disorder (SAD) (20).
Sleep and mood are closely linked. The sleep hormone, melatonin, is made from the mood neurotransmitter, serotonin, so if serotonin is low, so will be melatonin. Getting only 4.5 hours of sleep a night for just 1 week was enough to result in feeling stressed, angry, sad, and mentally exhausted (21). These changes were quickly reversed by a return to normal sleep. Difficulty sleeping can be the first sign of mental health problems and whether it is a cause or an effect, taking steps to ensure a good night’s sleep seems wise
Managing stress is vital: mindfulness-based stress reduction (MBSR) and meditation are very powerful in improving mental health (22).
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