Butter is made by churning milk. In this process the milk fat is agitated and this causes a change in the physical composition of the milk. Milk is an emulsion whereby the fat molecules are suspended in the watery medium of the milk and this is possible because the fat is surrounded by lipoproteins. Churning the butter causes the lipoproteins to be disrupted and the fat then starts to coalesce. As this process continues the milk fat particles continue to form together and eventually the product becomes butter. This is then cut into blocks, wrapped, and sold. Salt is sometimes added for flavour, depending on the tastes of the consumer. Butter is therefore totally natural and compositionally similar to cream. The fatty acids in butter tend to be short chain fatty acids and are readily oxidised in cells and are therefore a good source of energy. The cholesterol and saturated fat content of butter is relatively high, and this has been politicised by food manufacturers to encourage consumption of vegetable spread alternatives to butter.
The use of vegetable oils to make spreads is largely because they are cheaper than butter and so greater profits for food manufacturers. Vegetable oils are found in spreads alone, such as the case with margarine, or in combination with butter. The main problem with vegetables oils as spreads is two fold. Firstly, they are high in omega-6 fatty acids and the typical Western diet already contains too many omega-6 fatty acids. This leads to an imbalance in the omega-3 to omega-6 fatty acid ratio and this then causes inflammation. The second problem with the vegetables oils in spreads is that they are chemically altered during extraction from the plant material, and this results in oxidised, rancid oils that contain trans fats and free radical inducing chemicals. Vegetables oils are mostly liquid at room temperature, but when incorporated into spread they become solid. While the solidifying of milk to form butter is a physical process, the solidifying of vegetable oils is chemical, and this creates fatty acid products that are damaging to the health.
Certain vegetable spreads also claim to be able to lower plasma cholesterol, because of the phytochemicals they produce. However, no long term studies have been done on what amounts to a pharmacological effect from consuming a product that does not exist in nature. It is the sterols and stanols in vegetable spreads that are responsible largely for the lowering of cholesterol levels. While vegetable spreads are effective at lowering cholesterol levels in humans, it is unclear as to the benefit of this process, largely because the mechanisms of action, the metabolic changes that occur and the long term implications have not been extensively studied. The fact that vegetable spreads may contain oxidised and altered fatty acids may negate any benefits from any cholesterol lowering effects, for example. As sterols and stanols are supplied by a diet rich in plants, but without the oxidised and altered fats, there is no health benefit, and likely health problems, associated with consuming such vegetable spreads.
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