Nutrition for infants

Pronova Biocare

In nutritional terms, the expression "essential" refers to a large number of substances, which are crucial to good health, but not produced by the body. Such essential substances must be supplied through the diet.

These substances are even more important during pregnancy as all foetal nutrition comes from the mother. The fact is that newborns are not able to produce many of the nutrients that adults can produce from other essential substances. Consequently, "essential" substances are even more crucial for babies than for adults.

The classic examples used to demonstrate the importance and, indeed, the essential nature of nutritional elements, are vitamins. As early as in the 17th century, it was discovered that sailors could avoid scurvy if they supplemented their normal diet with cress, sauerkraut and orange extracts, all good sources of ascorbic acid, also known as vitamin C.

Vitamins, minerals, essential amino acids and essential fatty acids are all essential substances that must be consumed regularly to maintain good health.

About fatty acids
Fatty acids are classified as either saturated or unsaturated. Saturated fatty acids have all the hydrogen they can hold on their chemical chains, with single bonds linking all their carbon atoms. Unsaturated fatty acids are missing one or more hydrogen pairs. In monounsaturated fatty acids, the "missing" hydrogen pair is compensated by a double bond between two carbon atoms. If there are double bonds between more than two carbon atoms, the fatty acid is referred to as polyunsaturated.

Essential fatty acids
Various plants produce polyunsaturated fatty acids. Because they are vital for normal life functions, they are known as essential fatty acids. Polyunsaturated fatty acids reach human beings through the food chain, either directly through fruit and vegetables or indirectly through the flesh or eggs of animals, birds or fish that have eaten plants containing polyunsaturated fatty acids.

Essential polyunsaturated fatty acids belong to one of two "families", the Omega-6 family or the Omega-3 family, depending on the position of the double bonds in the fatty acids. The two families differ not only in their chemistry, but also in their natural occurrence and biological function.

Omega-6 fatty acids are typically produced by terrestrial plants so they will be present in that part of the food chain. For example, Omega-6 oils are found in cooking oils such as corn oil and soybean oil. Omega-3 fatty acids, on the other hand, originate mainly from marine plankton and are heavily represented in the marine food chain. Man's most important source is high-fat fish.

It is important to realise that polyunsaturated fatty acids need to be present in the diet in certain relative quantities. Ideally, the dietary ratio of Omega-6 to Omega-3 should be about 4/1. However, typical modern Western diets have an Omega-6 / Omega-3 ratio of between 10/1 and 20/1, which is not a healthy dietary situation.

Healthy adults can metabolise a-linolenic acid, the short-chained members of the Omega-3 family, into the long-chained fatty acids of the Omega-3 family. However, only about 5 per cent of the a-linolenic acid we ingest is metabolised into docosahexaenoic acid (DHA), which plays a special role in the brain, other neural tissues and the light sensitive cells in the retina of the eye.

Omega-3 during pregnancy
DHA is present in relatively large amounts in cerebral tissue. In fact, 15-20 per cent of the fatty substance in the cerebral cortex is comprised of DHA. In quantity, this adds up to more than 20 grams of DHA in an adult brain. Even more DHA rich is the retina, where DHA accounts for 30 to 60 per cent of the fat.

The brain of a newborn baby already contains large amounts of DHA. To ensure normal development of the brain and other neural tissue, a foetus requires large amounts of DHA.

A foetus obtains all its nutrients through the placenta, placing additional demands on the mother's nutrition in terms of energy as well as essential ingredients. In the event of a relative deficiency, the foetus will most often receive priority, meaning the mother's reserves will be depleted. A well-known example of this is anaemia during pregnancy.

A study conducted in the Netherlands demonstrated that women's DHA depots were depleted during pregnancy. With a diet relatively low in polyunsaturated fatty acids, it will take a long time to replace the lost DHA. Women who had had more than one pregnancy demonstrated a reduction in DHA, which was proportional to the number of pregnancies.

Several other studies have demonstrated that maternal brain volume is reduced during pregnancy. There is a theory that this may be caused by foetal demands for DHA. Brain volume normalises again within six months of delivery. Although it has not been proven that this DHA drain during pregnancy has any correlation with postpartum depression, it has been observed that DHA levels are often sub-normal in patients suffering from other types of depression, making this theory worthy of further research.

Serum concentrations of Omega-3 fatty acids increase during pregnancy, probably reflecting a biological adjustment to ensure that the foetus has access to sufficient Omega-3 fatty acids to develop normally. Expectant mothers suffering from preeclampsia tend to have low serum concentrations of Omega-3.

The clinical consequences of an insufficient intake of Omega-3 during pregnancy are not entirely clear, but it is thought that deficiencies increase the risk of premature birth. Due to advances in medical treatment, the survival rate for premature babies has improved immensely in recent years. In spite of this, premature babies still have a tendency to develop more slowly, both physically and intellectually, than full-term babies with normal birth weight. This is particularly true of the development of vision. Yet another long-term effect is that low birth weight babies have been shown to have a higher risk of developing cardiovascular disease as adults than those who were born with normal birth weight.

Omega-3 and newborns
Normal postnatal development calls for an adequate supply of essential Omega-3 fatty acids. Babies are not able to metabolise EPA and DHA from other essential fatty acids the way normal adults are to some extent able to do.

Mother's milk normally contains relatively large amounts of Omega-3 fatty acids, both EPA and DHA, together with other long-chained polyunsaturated fatty acids. This is nature's way of safeguarding a vital supply of the fatty acids so essential to infant development. However, most maternal milk substitutes do not contain Omega-3 fatty acids.

Recent research from New Zealand shows that children who have been breastfed experience better intellectual development than children who have received mother's milk substitutes. The observed variations may be related to factors other than differences in nutrition, for example, that breastfed babies get more stimulation than bottle-fed babies who receive mother's milk substitutes. There is, however, no reason to believe this. Two separate studies done on people born in 1915-20 and in the 1930s, respectively, indicate that the observed differences are mainly related to the nutrition. Before 1940, mother's milk substitutes were mainly used by the upper socio-economic classes. Both studies found that those who had received mother's milk were better off intellectually as adults, despite coming from a lower socio-economic background. The difference observed in New Zealand is probably related to the presence of essential fatty acids in mother's milk.

More recent research from Scotland demonstrated that supplementation with arachidonic acid and DHA improved infants' problem-solving abilities.

Research published in 1967 indicated that children whose mothers had bile duct problems experienced slower intellectual development than children whose mothers had no such problems. The explanation is probably related to abnormal and significantly reduced nutrient absorption, particularly of long-chained polyunsaturated fatty acids, in people with bile duct problems.

Adding marine Omega-3 to mother's milk substitutes might well add to their value.

DHA and mothers
Depletion of maternal DHA reserves during pregnancy and lactation has, as mentioned, been suggested as one possible cause of postpartum depression.

It has been shown that patients suffering from severe mental depression have low levels of Omega-3 fatty acids. The hypothetical relationship between mental health and fish consumption was suspected already in the 17th century.

As early as in 1621, the English author Robert Burton recommended that people suffering from depression should eat foods that we now know are rich in DHA. In his book Anatomy of Melancholy, he wrote that people suffering from depression ought to eat borage oil, a substance extracted from borage plants (used around the Mediterranean as a soothing treatment) and have a diet rich in fish. In special cases, a 14-day diet of ox brain was recommended. Such a dietary adjustment would result in a major increase in the intake of polyunsaturated fatty acids, particularly long-chained arachidonic acid and the Omega-3 fatty acid DHA.

Modern research from Rotterdam seems to verify this hypothesis.

Positive effects of DHA supplementation have also been reported in children suffering from Attention Deficit/Hyperactivity Disorder (AD/HD).

The nutritional gap
International nutrition organisations suggest that about 0.3 per cent of people's daily energy intake should be comprised of polyunsaturated fatty acids in the form of EPA and DHA. At least 0.1 per cent should be DHA, preferably in a ratio of Omega-6/Omega-3 of about 4/1.

While the recommended daily intake of marine Omega-3 fatty acids should be in the range of 0.6 to 1 gram, a "normal" diet in the Western world only covers about 10 to 15 per cent of this requirement. The remaining requirement, that is, the "nutritional gap," can be covered either by increasing the consumption of high-fat fish or by using suitable dietary supplements.

Why is DHA so important?
Generally speaking, polyunsaturated fatty acids are important components in cell membranes, the "walls" surrounding all living cells. The composition and structure of cell membranes are very important for maintaining normal cell functions. DHA is particularly important in brain tissue, as well as in other neural tissue and in the retina. DHA helps ensure the smooth transmission of electric impulses.

A normal adult brain contains more than 20 g of pure DHA, and the presence of DHA in the retina makes this essential Omega-3 fatty acid crucial for normal vision. Thus an adequate supply of DHA is of the utmost importance for the normal development of the brain, neural and retinal tissue in foetuses and newborns.

Marine oils - a high level of research activity
Research undertaken in the early 1970s clearly showed the biological importance of marine Omega-3 fatty acids. Such early observations created quite a sensation, resulting in a large number of biological and clinical experiments involving marine Omega-3 fatty acids.

As of year-end 1998, more then 6000 scientific articles and reports had been published on the various effects of Omega-3, and research efforts are becoming ever more comprehensive. Much of today's research revolves around the value of marine Omega-3 fatty acids in relation to the physical, mental and intellectual development of premature babies and infants.

There is growing acceptance the world over of the idea that marine Omega-3 fatty acids are beneficial to people's health. There is also increasing acceptance of Omega-3 fatty acids as a supplementary treatment for patients suffering from certain diseases. Accordingly, products containing Omega-3 fatty acids are registered as pharmaceuticals or natural medicine products in a large number of countries.

Marine Omega-3 fatty acids are now available in most countries as dietary supplements, registered natural medicine products or additives to vitamin and/or mineral supplements. Naturally, the relevant regulations vary from country to country owing to differences in legislation and traditions.

Generally, a daily intake of 1 to 1.5 grams of Omega-3 fatty acids is recommended. This recommendation leaves a good margin of safety since intakes of up to 10 grams per day have been reported to have no harmful effects. Daily doses of more than 3 grams daily are used when Omega-3 fatty acids are used as a supplementary treatment for specific diseases.

Why is dietary supplementation with marine Omega-3 essential?
Foetuses deplete maternal DHA reserves. If expectant mothers fail to take a suitable Omega-3 fatty acid supplement, they may experience a relative deficit of the substance. It has been suggested that depletion of cerebral DHA may be a factor in the development of postpartum depression.

Foetuses and newborns need a large amount of marine Omega-3 in general and DHA in particular. DHA deficiencies have been found to delay intellectual development and the development of visual acuity.

Which marine Omega-3 product to choose?
DHA is essential to the optimal development of foetuses and newborns. Although mothers can transform EPA to DHA, DHA is easily absorbed from the intestine in the form of EPA. Accordingly, it is best to use a DHA-rich product for dietary supplementation of marine Omega-3. This choice takes into account any uncertainty regarding the mother's ability to transform EPA to DHA.

Any marine Omega-3 products added to mother's milk substitutes should be DHA rich since babies do not have the requisite capacity to transform EPA to DHA.