It seems like everyone I see in my practice these days avoids fats. When recalling their daily diet to me, they proudly point out all the low fat and fat free foods they eat. This is all very well, but I tend to not be too impressed. The reason is that fat is essential for good health. I also find that many children I see in my practice are on a low fat diet by default – their parents are eating everything low fat and thus the children end up eating lots of low fat foods (which are mostly high carb), which can be very risky. Indeed, the increasing incidence of obesity and diabetes in children and adults alike is linked to carbohydrate intake, not fat intake.
Babies and young children need to obtain around 50% of their diet from fats. Breast milk is 50% fat (mostly cholesterol and omega 3 fats) and this provides one of the most important building blocks for normal brain development. Sixty percent of the brain is composed of fat and thus fats are essential for healthy brain function. Supplemental omega 3 fats (found in fish oils) have been shown in studies to increase IQ in babies and prevent behavioural problems. Mothers taking fish oils are also less likely to develop postnatal depression, as omega 3 fats play a role in normal mood. Pregnant women and breastfeeding mothers are at risk of omega 3 fat deficiency as the baby depletes her reserves. It follows that if the mother is deficient then her baby is also at risk of deficiency of this crucial nutrient.
Fats are needed for hormone production, for absorption of certain nutrients and for healthy cell function. Fat in a meal also slows down the absorption of other foods such as sugars and increases satiety – a fact often overlooked. Most fat free products contain additional sugars and flavours to make up for this. This in turn adds calories to the product and can potentially lead to weight gain despite its fat-free label. Many people report being hungry again soon after eating fat free products which may cause them to eat more.
Vitamins A, D, E and K can only be absorbed in the presence of fat, hence they are known as fat soluble vitamins. They are also found in the fatty part of the foods they are contained in. So when we eat low fat versions of certain foods, such as dairy, these essential vitamins are lost. It is also important to note that vitamin D which is found in good quantities in full fat dairy products helps to assimilate calcium. Vitamin D is so important that many low fat milks have synthetic vitamin D added back in to compensate for this loss and make the calcium more available. The synthetic version of vitamin D, however, is not quite as good as the real thing.
Vitamin A is a crucial vitamin that I often see deficiencies in – especially when people are on a low fat diet. Vitamin A is very important for babies and children. It is involved with brain function, immunity, eye development and function and healthy skin and mucous membranes.
While beta-carotene in plant foods may be able to be converted to active vitamin A, there is evidence that children and those with poor gut function or fat deficient diets are poor converters. It is far more reliable for children to get the active form of vitamin A in their diet as they are going through major growth and development.
Interestingly, the highest amounts of these essential vitamins are found in animal fats (largely saturated fat) which everyone has been warned off eating in recent years. Animal fats have been in the human diet for thousands of years and have proven safe and also nourishing. We need to be sensible when altering our diet and be aware of what we are missing when we change things too much.
So hopefully we have established that fats are essential in the diet but all fats are not equal when it comes to health. Lets look at different fats and see which ones are good for us and which ones are not so good. Fats are categorised according to their level of saturation of double bonds in their basic chemical structure. In reality, all fats are made up of different amounts of saturated, monounsaturated and polyunsaturated fatty acids. The dominant one is the one they are grouped under.
Saturated Fats – saturated fats are found mostly in animal foods (eg. meats & butter), but also in coconut and palm oils. While these fats have been demonised in recent years, saturated fats make up 50% of every cell membrane in the body and are required for a host of body functions including healthy immunity. Saturated fats are also very stable for cooking and were what previous generations relied on.
Sources: fatty portion of meats, chicken, eggs, butter, cream, full-fat cheese & milk.
Monounsaturated Fats – the most common monounsaturated fat is olive oil, but many people are surprised to learn that lard (pig fat) is also a monounsaturated fat. Most people are aware that monounsaturates are healthy fats that are stable to heat as they only have one double bond available for oxidation.
Sources: olive oil, nuts & seeds, avocado, lard.
Polyunsaturated Fats – this large group of fats contains lots of double bonds making it more vulnerable to oxidation and damage. The polyunsaturates include the wonderful omega 3 fats linked to healthy hearts, brains and happy moods. While many of these oils have health benefits, they should never be heated in cooking as they can create cancer causing free radicals.
Sources: cold pressed vegetable, nut & seed oils, fish oils, flaxseeds, walnuts.
Trans Fats – these are not generally found in nature and are formed when polyunsaturated fats are hydrogenated. The process of hydrogenation is used when food manufacturers turn liquid vegetable oils into margarines or other solid fats and in the process changes its shape making it a very unstable free radical. These unstable and dangerous trans fats can damage healthy cells in the body and have been linked to cardiovascular disease and cancer. Avoid margarines and all commercial foods containing margarines or hydrogenated fats such as biscuits and pastries (check labels).
Healthy foods should be the basis of the diet for toddlers and young children and must also contain healthy fats to ensure optimal development.