Animal life first originated in the sea, where there was an abundance of omega-3 fatty acids – the same fatty acids that now form the essential components of our eyes' photo receptors and our brain's cell membranes.

As time went on, flowering seed plants appeared and with them a brand new fatty acid family was introduced. The seed oils of these plants contained what we call omega-6 fatty acids. For the first time, the omega-3 and omega-6 fatty acid families existed on earth together and apparently this opened the door for an entire new set of species to arrive that would develop bigger brains.

How did the new species develop bigger brains?

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Unlike the fish, amphibians and reptiles of the time, the new species, called mammals did not lay eggs. Mammals, kept their offspring inside of their bodies, surrounded by a sac called a placenta.

The placenta is a powerhouse of nutrients and energy and 70% of the calories are devoted to brain growth. No wonder they grew bigger brains.

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Human beings are thought to have lived on earth for millions of years, however the big brain change happened only in the last 200,000 years or so.

What could have caused the change in human brains? And why did some human brains change and others stay the same? Could it have been what they ate?

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The puzzle of the big brain change involved scientists putting together pieces that at first look had no relation. The first piece of the puzzle involved discovering early human populations that demonstrated greater intelligence. They found evidence in the East African Rift Valley and on the southern Cape of South Africa. The second piece of the puzzle was the discovery that docosahexaenoic acid, (DHA), was a large contributor to brain growth. The third piece was the discovery that DHA was found in seafood. When scientists put all the pieces together they found that the early humans who lived near water sources and ate seafood experienced the big brain change!

Stone age women collecting shellfish could have easily provided themselves with a plentiful source of brain-specific nutrition, and their children would have naturally participated in exploitation of this extremely rich resource. There must have been enough omega-3 and omega-6 fatty acids available in their diet to provide many generations with fuel for fetal/infant development as well as childhood and adult needs for the cardiovascular system and the brain.

In contrast, the inland Australopithecines did not have access to omega 3 EFAs and got stuck at a brain capacity that was not much bigger than a chimpanzee for three million years.

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Erik Trinkaus and his colleagues at Washington University in St. Louis analyzed the bones of Neanderthals who lived 28,000 to 130,000 years ago in Europe. The results suggest that Neanderthals ate mostly red meat from the larger animals that roamed Europe at that time.

In contrast, the bones of early modern humans found in Britain, Russia, and the Czech Republic (dated 20,000 to 28,000 years ago), showed that fish and seafood accounted for 10 - 50% of their dietary protein.

"The apparently broader dietary spectrum of the early human economy may have rendered humans more resilient to natural pressures and the increasingly packed social environments of Late Pleistocene Europe," the researchers said.

Stephen Cunnane, a professor of nutrition at the University of Toronto called the study "an important finding" that supports a theory that DHA from seafood boosted the brain power of early humans. "You don't need a big brain to collect mussels and clams, but living on them gives you the excess energy and nutrients that can be directed toward brain growth," he said.¹

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The membranes of neurons – the specialized brain cells that communicate with each other – are composed of a thin double-layer of fatty acid molecules. Fatty acids are what dietary fats are composed of. When you digest the fat in your food, it is broken down into fatty acid molecules of various lengths. Your brain then uses these for raw materials to assemble the special types of fat it incorporates into its cell membranes.

Passing through a cell's membrane into its cell's interior are oxygen, glucose (blood sugar), and the micronutrients the cell needs to function. Metabolic waste products must exit, so the cell won't be impaired by its own pollution.

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Myelin, the protective sheath that covers communicating neurons, is composed of 30% protein and 70% fat. One of the most common fatty acids in myelin is oleic acid, which is also the most abundant fatty acid in human milk and in our diet.

Monosaturated oleic acid is the main component of olive oil as well as the oils from almonds, pecans, macadamias, peanuts, and avocados.

Myelin fiber

©1998 Dr. Norberto Cysne Coimbra M.Sc., Ph.D., Laboratory of Neuroanatomy and
Neuropsychobiology, Faculty of Medicine of Ribeirão Preto of the University of são Paulo; Neuroscience Art Galleries

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Human and animal studies show that nutrition has a big influence on myelination, especially for nursing infants. French researchers found that dietary trans fatty acids did indeed find their way into the myelin of brain cells, where they changed the electrical conductivity of the cells. Furthermore, when the (rats') diets were already deficient in omega-3 ALA (alpha-linolenic acid), then the incorporation of trans fats was apparently doubled.²

In a Canadian study of human breast milk, trans fatty acids (TFAs) averaged 7.2% of the total fatty acids. Partially hydrogenated vegetable oils were determined to be the major source of these unnatural fats. Also, levels of LA (linoleic) and ALA were inversely related to the total TFAs, indicating that the elevation of TFAs in Canadian human milk is at the expense of essential omega-3 and omega-6 fatty acids.³

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DHA (docosahexaenoic acid) and AA (arachidonic acid) are both crucial to the optimal development of the brain and eyes. During pregnancy the mother supplies the developing fetus with these fatty acids, and she continues to provide this important brain food to her infant through breast milk.

Specific deficits of essential fatty acids in fetal umbilical cords at birth correlate to low birth weight, small head circumference, and low placental size.⁵ This is significant, because birth weight and head size are associated with growth factors that influence later development of the central nervous system and cognitive ability.⁶

When the formula of 10-month old infants was supplemented with DHA and AA, it was found that "an infant's three-step problem solving ability is significantly improved" – and persisted beyond the period of supplementation.⁴

The importance of DHA and AA in infant nutrition has been demonstrated many times, and both substances are routinely added to infant formula throughout Europe and Asia.

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From ALA and LA, your brain can make (docosahexaenoic acid) DHA and (arachidonic acid) AA the longer chained fatty acids that are incorporated in its cell membranes. These more complex fatty acids are also available, preformed, directly from food.

This is important, because the brain's ability to assemble these fatty acids can be compromised by stress, infections, alcohol, excess sugar, and vitamin or mineral deficiencies – factors common today.

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DHA (docosahexaenoic acid) is the most abundant fat in the brain. Loss in DHA concentrations in brain cell membranes correlates to a decline in structural and functional integrity of this tissue.

Also, the oxidative damage that comes with age causes a decline in membrane DHA concentrations, and with it, cognitive impairment.

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Scientists at the National Institutes of Health associated the increase in depression in North America during the last century with the decline in consumption of DHA (docosahexaenoic acid) during the same period. Although many stresses of modern life contribute to the prevalence of depression, Joseph R. Hibbeln, M.D., and Norman Salem, Jr., Ph.D., concluded in 1995 that the "relative deficiencies in essential fatty acids may also intensify vulnerability to depression."

They also pointed to lower rates of major depression in societies that consume large amounts of fish, a key dietary source of DHA. North American and European populations showed cumulative rates of depression 10 times greater than a Taiwanese population that consumed a lot of fish. The Japanese, whose diet is rich in fish, have a significantly lower prevalence of depression compared to North America and Europe.

Belgium researchers at Antwerp's University Hospital found that seriously depressed patients had lower omega-3 fatty acid levels than mildly depressed patients.⁷

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Type 2 diabetes used to be called "adult-onset" diabetes, because it mostly occurred in people A Dutch study of cognitive function in males, aged 69-89, suggests that a high intake of omega-6 fatty acids (found in red meat) is "positively associated with cognitive impairment and high fish consumption inversely associated with cognitive impairment."⁸

Scientists at the USDA's Laboratory of Neuroscience and at the Jean Mayer Human Nutrition Research Center on Aging at Tufts University reported that neurodegenerative disorders such as Parkinson's and Alzheimer's appear to exhibit membrane loss of fatty acids. "Thus it may be that an optimal diet with a balance of omega-6 and omega-3 fatty acids may help to delay their onset or reduce the insult to brain functions which these diseases elicit."⁹

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DHA (docosahexaenoic acid) was the subject of an April 1997 conference on nutrition and the brain. Leading experts discussed the link between low levels of DHA and certain neurological conditions. At the conference, "Keeping Your Brain in Shape: New Insights Into DHA," researchers also noted studies showing a link between deficient DHA levels and hostility and aggression.

Ernst Schaefer, M.D., of the Human Nutrition Research Center on Aging at Tufts University, has found that a low level of DHA is a significant risk factor for dementia, including Alzheimer's disease. He has discovered that the body may experience a decreased ability to make DHA as it ages. "The data I have seen suggest that DHA may be an important therapeutic modality in some age-related conditions, including Alzheimer's and heart disease," Schaefer commented.

Adam Drewnowski, Ph.D., director of the Program in Human Nutrition at the University of Michigan, added that cognitive deficits and dementia in the elderly may be associated with inadequate diets. "Current studies on nutrition in the elderly suggest that many conditions associated with aging, such as loss of appetite and forgetfulness, may be avoided if optimal nutrition is maintained through a diet including nutrients like DHA."

Research indicates that "DHA may be a critical component of the diet of people of all ages," said Barbara Levine, R.D., Ph.D., director of the Nutrition Information Center at the New York Hospital-Cornell Medical Center.

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Some researchers believe an imbalance of omega-3 and omega-6 fatty acids may lead to a variety of mental disorders, including hyperactivity, depression, brain allergies, and schizophrenia. A balanced ratio of the two fatty acid families (omega-3 and omega-6) is necessary for a healthy brain, which is structurally composed of a 1:1 ratio of omega-6 to omega-3. Western diets, however, tend to have at least twenty times more omega-6 fats (from meat and dairy) than omega-3 fats–an unhealthy ratio of 20:1.

This imbalance can be corrected by eating more omega-3-rich fish and flax seed oil, by eating less sugar, and by completely avoiding trans fatty acids found in partially-hydrogenated oils, margarine, and shortening. In fact, to err on the side of safety, avoid "supermarket" oils and salad dressings unless they are clearly labeled "cold-pressed" – or in the case of olive oil, "extra virgin."

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Adding DHA (docosahexaenoic acid) and AA (arachidonic acid) to infant formula significantly boosted the average intelligence scores in a group of children, according to a 2000 study funded by the U.S. National Institute of Child Health and Human Development.

The study tested the intelligence scores of 56 infants, 18 months old. One group received formula containing only DHA, while another received one containing DHA and AA. The control group's commercial formula did not contain either substance. All three groups of infants were enrolled in the study within five days of their birth, and for 17 weeks received one of the three formulas.

When the children's overall intelligence was tested, they differed significantly on the Mental Development Index (MDI) that measures young children's memory, their ability to solve simple problems, and their language capabilities.

The children in the control group received an average MDI score of 98 – slightly below the national average of 100 for U.S. children. The DHA group received an average score of 102.4, and the DHA plus AA group received an average score of 105.¹⁰

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In an analysis of 20 published reports, researchers at the University of Kentucky Chandler Medical Center found that the IQs of breast-fed babies are higher than that of formula-fed babies.

The nutritional benefits of breast-feeding are associated with at least a 3.2 IQ point difference in cognitive development – after adjustment for key factors, such as the mother's age and intelligence, birth order, race, birth weight, gestational age, and socioeconomic status. This is in addition to a 2.1 point increase associated with maternal bonding.

The enhanced cognitive development was seen as early as six months and was sustained through 15 years of age. And, the longer a baby was breast-fed, the greater the increase in cognitive developmental benefit.

"This study confirms that nutrients in breast milk and maternal bonding have beneficial effects on IQ," said James W. Anderson, M.D., professor of medicine and clinical nutrition at UK College of Medicine. "Infants deprived of breast milk are likely to have lower IQ, lower educational achievement, and poorer social adjustment than breast-fed infants."¹¹

Norwegian researchers tested 345 children at the ages of 13 months and five years. The children who had been breast-fed for less than three months were more likely to score below average on mental skills at 13 months, compared to the children breast-fed for six months or longer. And at age five, this longer breast-fed group averaged eight points higher in IQ.¹²

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An 18-year study concluded that (docosahexaenoic acid) DHA was the likely breast milk nutrient that provided the improved academic outcome experienced by breast-fed children.¹³

Mother's milk is high in DHA, and children who receive adequate amounts of DHA were shown to have higher IQs, as well as better vision than children who didn't get enough DHA.¹⁴

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Any discussion of the brain must include the vast network of blood vessels that serve it. The 400 miles of capillaries in the human brain have a surface area of approximately 100 square feet. And, the health of these vessel walls is paramount to proper brain function.

The development of this intricate infrastructure of blood vessels was essential to the evolution of the human brain itself. Not only is the bloodstream a river of life constantly delivering oxygen, glucose, and nutrients to the brain – and removing toxins – it also cools the brain.

One of the bloodstream's important functions is to keep brain cells from overheating. Before the human brain could evolve greater mass and density, a "radiator" network of cranial veins had to evolve – otherwise the constant heat generated by brain activity would burn out its cells.

In other words, efficient blood flow throughout the brain was absolutely necessary to the development of higher intelligence – then and now. This underscores the essential connection between optimal brain function and a healthy and efficient cerebral vascular system.

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Studies show that the trans fatty acids we eat do get incorporated into brain cell membranes, including the myelin sheath that insulates neurons. They replace the natural DHA in the membrane, which affects the electrical activity of the neuron.

Trans fatty acid molecules disrupt communication, setting the stage for cellular degeneration and diminished mental performance.¹⁵

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Brain cells need a certain degree of flexibility to function properly. This is accomplished by a maintaining a balance of different types of fatty acids in the cell membrane.

The particular physical size and shape of individual fatty acid molecules is what gives the brain cell membrane its structural flexibility and fluid-like properties.

Cell soma of individual neuron

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Normal fatty acids have a natural curve to their molecular shape. When they fit together in vast numbers, enough space still remains so that the membrane has the proper structure it needs to function at its best.

However, if these same fat molecules are changed by manufactured food processes, or if they are heated for long periods – as in deep frying – they mutate into a form rarely found in nature. Now their molecules are straighter, narrower, and no longer have their original curved shape.

This means that these altered fats will pack more tightly together into the cell membrane, making it more saturated and rigid – less flexible and less able to function properly. These altered fats are called "trans fatty acids," and are finally being recognized for the damage they cause. For half a century, however, hardly any attention was paid to them.

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A trans fat diet was compared to a saturated fat diet – each with 9% of calories from fat. The trans fats came mostly from margarine made with partially hydrogenated soybean oil, while the saturated fat came from palm kernel oil margarine. Twenty-nine healthy men and women were randomly assigned one of the diets for a month, then they switched to the other diet for the next month.

Researchers found that trans fats are more detrimental to the ability of blood vessels to dilate, a marker for heart disease risk. Trans fats reduced this blood vessel function by a third – and lowered (good) HDL-cholesterol by a fifth – compared to saturated fats. Both increased (bad) LDL-cholesterol levels.

"This suggests that trans fatty acids increase the risk of heart disease more than the intake of saturated fats," concluded the scientists at Wageningen University in the Netherlands. It suggests that if French fries were cooked in saturated fat instead of in hydrogenated vegetable oils, they would probably be safer.¹⁶

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Italian senior citizens who consumed extra-virgin olive oil as their main dietary fat were less likely to experience age-related cognitive decline, compared with people who ate less monounsaturated fats. "It seems that in the aging process there is an increasing demand for unsaturated fatty acids," concluded Dr. Antonio Capurso at the University of Bari. About 15% of the seniors' daily calories were from olive oil.¹⁷

Healthy monounsaturated fats are found also in avocados, peanuts, walnuts, almonds, pecans, chicken, beef, turkey, eggs, mackerel, and herrings, as well as in sesame, palm, corn, sunflower, and soybean oils.

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