Peanut butter is a very caloric, yet very healthy food. In general, raw peanut butter (as in less refined) is better than refined, because it retains many of the beneficial nutrients found in the skin; in addition, processed peanut butter might contain added trans-fatty acids (which have been shown to increase the risk of cardiocirculatory diseases). A further risk is that when badly preserved, it can host the mold Aspergillus flavus, that produces aflatoxin (a very toxic and carcinogenic substance), so your best bet is to always go with natural peanut butter.
The calorie breakdown for peanut butter is:
This means that the vast majority of calories come from fats, which is why it is generally advised that obese people avoid eating too large an amount of peanut butter.
The total calorie content in 100 grams of peanut butter is 589Cal, placing it among the most caloric foods in the typical U.S kitchen. A more detailed breakdown can be found in our peanut butter nutritional data page.
Most of the fats contained are however monounsaturated, and have been shown to improve the cholesterol profile by lowering "bad" LDL cholesterol.
This effect is compounded by peanut butter containing polyunsaturated fats, which in turn help raising the "good" HDL cholesterol; the synergistic effect makes this spread a very good cholesterol regulator.
In a randomized, cross-over, double-blind study involving 22 subjects, a high monounsaturated diet that emphasized peanuts and peanut butter decreased the risk of cardiovascular diseases by 21% compared to the average American diet.
Peanut butter contains fairly high quantities of dietary fiber, amounting to about 8%, which again helps in regulating both blood cholesterol and blood sugar levels.
Dietary fiber has also been shown to significantly reduce the risk of colo-rectal cancer (which is among the most common causes of death by cancer in civilized countries) and atherosclerosis (another common disease in the U.S. and Europe).
Proteins are present in high amounts (about 24% in weight), together with very important micro-nutrients such as Vitamin E, Vitamin B3 and large amounts of beneficial minerals such as iron, magnesium, potassium, copper and calcium.
Vitamin E is one of the most powerful liposoluble antioxidants, shown to significantly reduce the risk of cancer and cardiovascular diseases; Vitamin B3 (also known as Niacin) is a water-soluble vitamin that aids in the recovery of cell DNA damage (thus protecting from cancer) and in improving sexual bodily functions by assuring the proper secretion of sexual hormones.
The minerals peanut butter contains are in variable amount (raw peanut butter with crushed skin contains much higher amounts than refined "nut-only" butter): iron is essential for the correct functioning of your red blood cells, while calcium promotes healthy bones and shields against muscle spasms.
Although not among the richest foods in potassium, peanut butter still contains fairly good amounts of it, and research has indicated that diets rich in potassium reduce the risk of hypertension (bananas are, however, a better source of potassium, try making a banana and peanut butter sandwich!).
One of the most interesting and peculiar nutrients found in peanuts is Resveratrol: this is a natural antimicrobial agent, produced by the peanut plant (and in even larger quantities by red grapes) to ward off potential pathogens (bacteria, virii and fungi).
Resveratrol is actually believed to be the cause of the "French paradox" (French people having a lower risk of cardiovascular disease despite their diet rich in fats). Although harmless to humans, resveratrol is still active when ingested, and it provides the same anti-microbial and anti-fungal properties to the person consuming it. Academic research has shown a plethora of beneficial effects of resveratrol in mice, ranging from anti-cancer, antiviral, anti-aging, neuroprotective and anti-inflammatory to life-prolonging (most of these tests have not been carried out on humans yet, but the premises are there).
Another peculiar substance contained in peanut butter is p-coumaric acid, a polyphenol that helps combat oxidative stress (a syndrome believed to cause some neurodegenerative and cardiovascular diseases). Scientific sources such as the Food Chemistry concluded that roasting peanuts leads to a higher content in p-coumaric acid by as much as 22%.
In a test conducted during 20 years, on 80,000 female subjects by the Nurses' Health Study, it was observed that women who eat least 1 ounce of nuts, peanuts or peanut butter each week have a 25% lower risk of developing gallstones. This quantity can easily be reached by eating one peanut butter sandwich per week!
According to the Journal of Neurology, Neurosurgery and Psychiatry, the niacin contained in peanuts, when eaten regularly, provides protection against Alzheimer's disease.
The study was carried on 3000 elder men (65 or older) from Chicago, who were interviewed about their diet and subsequently tested for cognitive skills: those getting 22mg of niacin/day were 70% less likely to have developed Alzheimer's disease than those consuming 13 mg/day.
In addition to this, peanut butter contains much higher quantities of antioxidants than apples or carrots.
All things considered, peanut butter deserves a place in a healthy diet for the vast range of important nutrients it contains.
Because of its high fat and caloric content, however, some doctors argue that obese people should consume only little amounts of it: there is a lot of controversy about this, and there are many studies claiming that eating nuts more than twice a week actually reduces the risk of weight gain.
One of these studies was published on the journal Obesity, it involved 8865 adult men and women in Spain and was carried out during a 28-month period: the subjects who ate nuts at least twice a week were 31% less likely to gain weight (> 5kg) than the others.
Please keep in mind this is not medical advice, you should consult your doctor before adding peanut butter to your diet (especially in light of some people being highly allergic to peanuts).