Researchers have long linked consumption of tree nuts, despite their significant fat content, to decreased risk of cardiovascular disease, obesity, diabetes, cancer and even Parkinson's disease. Now comes evidence that they also improve cognition in general and specific ways. Most have high concentrations of vitamin E, the B vitamins (including folate), antioxidants, minerals such as magnesium, as well as omega-3 fats, all of which support myriad functions of the nervous system.
Crack open some walnuts and improve your ability to think critically. Researchers find that eating a high concentration of walnuts (half a cup a day) boosts inferential verbal reasoning, especially the ability to distinguish true from false. An array of compounds in walnuts, including vitamin E, folate, melatonin and varied antioxidative polyphenols, protect the central nervous system and speed synaptic transmission. The significant supply of alpha-linolenic acid is essential for stability of neuronal membranes, through which all neuronal actions transpire.
Although not strictly tree nuts -- they are the seed of a fruit related to plums -- almonds may help save your memory. Mice rendered temporarily amnesiac were more apt to remember their way around a maze 24 hours later if they first consumed an almond paste.
The evidence suggests that almonds slow the decline in cognitive abilities linked to Alzheimer's disease. Investigators attribute the memory effects to the presence of the essential amino acid phenylalanine and L-carnitine, believed to boost neurotransmitters essential to memory.
A hefty handful of Brazil nuts can spare the obese the vascular damage associated with adiposity. An excess of fat tissue stimulates low-grade inflammation and oxidative stress, both of which can lead to cardiovascular disease.
With high levels of unsaturated fatty acids and bioactive substances that combat inflammation -- selenium, phenolic compounds, folate and magnesium among them -- Brazil nuts improved microcirculation, lowered cholesterol levels and normalized blood lipid profiles without causing weight gain in 17 obese female adolescents.
For the world's 20 million diabetics, almonds may improve blood- sugar control while decreasing the risk of cardiovascular disease. In a randomized controlled study, a team of Chinese and American researchers found that four weeks of an almond-augmented diet improved blood lipid levels, abolished a postprandial rise in glucose levels and reduced body fat in 20 patients with Type 2 diabetes.
The magnesium, fiber, monounsaturated fat and polyphenols in the nuts all contribute to the improvements in glycemic control.
Pecans may slow the rate of age-related motor degeneration. University of Massachusetts scientists fed two versions of a nut- rich diet to rats specifically bred to develop motor-neuron decline. All pecan-fed animals outperformed control animals on subsequent tests of activity, and those fed the highest percentage of nuts outran them all. The researchers believe the high concentration of antioxidant vitamin E shields neurons from degenerative conditions such as amyotrophic lateral sclerosis or Lou Gehrig's disease.