Updated 04 November 2014

Too much of a good thing

One of the most common mistakes many people make, is to reason as follows: “The experts say that food X is good for me. Therefore, I can eat as much of the food as I like."


One of the most common mistakes many people make, is to reason as follows: “The experts say that food X, or drink Y is good for me. Therefore, I can eat as much of food X, or drink as much of Y as I like, and I will come to no harm!” 

This kind of reasoning is basically flawed and can lead to all kinds of problems, including overconsumption, as well as underconsumption of a variety of nutrients resulting in deficiencies, nutrient excesses and an unbalanced diet.

Many people say that they eat mind-boggling quantities of certain foods and drink vast quantities of certain beverages, including water, ‘because it’s good for me.’

a) Fruit and vegetables
Eating only fruits and vegetables may is not a good idea.

Firstly, excessive intakes of beta-carotene from dark orange and dark green fruits and vegetables such as carrots, pumpkin, butternut, spinach, mangoes, etc., can lead to storage of this substance in the body. There have been reports that people who eat too much of these foods actually turn yellow! Luckily, this is a condition that is easily reversed by cutting down the intake of beta-carotene-rich fruits and vegetables to normal levels. The vitamin which beta-carotene is changed into by our bodies, namely vitamin A, is another matter entirely (see c) Fat-soluble Vitamins, below).

Secondly, while fruits and vegetables are bursting with protective vitamins, minerals, bioflavonoids and dietary fibre, they are not our best source of many other nutrients. So if you have decided to become a ‘Fruitarian’, then you may be exposing yourself to the risk of protein, iron, calcium, vitamin B12, omega-3 fatty acid, and many more deficiencies. The trick is to eat plenty of fruit and vegetables TOGETHER with other healthy food choices, such as low-fat milk and dairy products (for protein, calcium, and riboflavin), eggs (for protein and iron), lean meat (for protein, iron and B12), fish (for protein, iodine, and omega-3 fatty acids) and unprocessed grains and cereals (for minerals and other types of dietary fibre).

b) Protein foods
Many people who are trying to gain or lose weight, or build muscle, believe that they need to overload their bodies with protein. Some eat really amazing amounts of protein and then still take protein or amino acid supplements to achieve muscle growth or weight-gain or -loss. If you keep in mind that the Recommended Dietary Allowance (RDA) for protein in the USA and South Africa is about 60g a day, an amount that is easily supplied by a single standard portion of meat or fish, or one egg, or some cheese, then you will realise that eating three to four eggs plus 500g of steak twice a day, is totally excessive. Too much protein can put strain on the kidneys and cause conditions such as acidosis, ketosis, kidney stones, and gout.

Excessive protein intake often also goes hand in hand with excessive intakes of dietary fat, particularly saturated fat and cholesterol, which can have harmful effects on heart health and increases the risk of certain cancers.

If you are trying to gain muscle, or slim, and take protein and amino acids supplements or shakes, in addition to all this dietary protein, then you are really putting your health at risk.

The solution is to eat moderate portions of lean protein foods together with all the other foods that make up a balanced diet and to do exercises which will build muscle, or slim the body.

c) Fat-soluble vitamins
The fat-soluble vitamins, namely vitamins A, E, D and K, are stored in the body. Vitamins A, D and K, can cause problems if you overdose on them. So if you take vitamin supplements that contain these vitamins (cod liver oil, etc), and/or eat foods rich in such vitamins (liver, meat, fish) in excess, then you run the risk of developing conditions such as hypervitaminosis A or D. These conditions are characterised by symptoms such as bone pain and fragility, dry, cracked skin, brittle nails, hair-loss, anorexia, irritability, tiredness and abnormal liver functions in the case of vitamin A, and headache, nausea, calcification of soft tissues and deafness in the case of vitamin D. An excess of vitamin K, is relatively rare, but it can cause clotting problems in patients receiving anticlotting therapy with medications such as warfarin.

Once again, these kinds of excesses can be avoided by not overdosing on vitamin pills or supplements like cod liver oil, or eating any single type of food in excess. Moderation is the key and a varied, balanced diet.

d) Liquids
Another human tendency is to consume great volumes of supposedly ‘safe’ liquids (water, fruit juice, rooibos tea). While we need to drink plenty of fluids, excessive amounts of water can in the long run be harmful and lead to depletion of important minerals and trace elements. So it is important to take fluids on a daily basis, but not to drown yourself in liquid as this can also have negative effects.

Fruit juices are another good example of how important it is to regulate one’s intake. Many people believe that just because fruit juices are basically healthy, they can drink litres of fruit juice a day without causing any harm. What is of greater concern, is the erroneous idea many parents have that their infants and children can drink as much fruit juice as they like without any of the negative side-effects associated with drinking other popular beverages such as carbonated cold drinks.

Fruit juices are excellent products, but if you drink too much on a daily basis they will contribute to weight-gain and tooth decay. Keep in mind that on average fruit juices contain 200 kJ per 100ml, so if you or your child, drink 6 glasses of 300ml a day, you and your child will be ingesting an additional 3600kJ a day! Unchecked drinking of fruit juices, especially in baby bottles, without rinsing the mouth or brushing teeth, can lead to tooth decay because fruit juices contain a lot of fermentable sugars.

So by all means include fruit juices in your balanced diet, but don’t think you can drink unlimited quantities without this having any negative effects.

The bottom line
The bottom line in all these examples is that even highly beneficial foods and beverages when consumed in excess, can be harmful. Be sensible and eat or drink a wide variety of foods and beverages and don’t ever overdose on any one food or drink, no matter how intrinsically good such foods and drinks are when consumed in moderation!

- Dr I.V. van Heerden, registered dietician.


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