Four myths on nutrition that you might have believed

1. “Sugar is toxic”

Let us start by defining “sugar” as sucrose, a natural carbohydrate. Its molecular unit is a disaccharide consisting of a molecule of glucose and one of fructose linked together. For thousands of years, sucrose has been part of the human diet and obtained mainly by extraction from sugar cane and sugar beets. The purification process can go as far as obtaining perfectly refined, white sugar; brown sugar, in contrast, is less pure and contains molasses, including some minerals that are absent in white sugar. Despite what we are sometimes told, brown sugar doesn’t only come from sugar cane, but it can as well be produced from beets.

Now, back to the main topic: is sugar toxic? A preliminary answer is: it depends. As for most things, toxicity depends on the quantity and not the quality of the substance.

When we ingest sucrose, it goes down to the gut where it meets the enzyme invertase, which splits the bond between the glucose and fructose units. In this way, glucose becomes available as an energy source for our body. This is especially important for some organs, such as the brain, which are unable to use anything else than glucose to draw energy. So, it appears like sugar could be essential to our survival. However, sucrose is not the only source of glucose for us: indeed, there are many foods from which we can obtain glucose, mainly those consisting of complex carbohydrates, such as bread, rice, potatoes, corn, peas, fruit, and honey. By reading this list, you must have thought that there are more than enough sources of glucose in the typical nutritional regime of the average person living in a developed country.

The average person living in a developed country is, also, more and more frequently affected by metabolic diseases, such as diabetes and obesity, along with all their unpleasant consequences. We eat too much, and we don’t always eat healthy food; that much is clear. Diabetes is a disease characterized by hyperglycemia, that is, an excess of glucose in the blood due to an insufficient production of the hormone insulin and/or the resistance of organs and tissues to the action of insulin. One can become affected by Type 2 diabetes owing to their genetic makeup and exposure to environmental factors, which are mainly obesity and a prolonged excess of sugary foods in their diet. The disease is chronic and can result in several negative outcomes, including eye, kidney, nervous, and cardiovascular damage.

Therefore, as we stated previously, the toxicity of sugar depends on its quantity. If ingested in limited amounts within a balanced nutritional regime, it is completely harmless. However, when consumed excessively for many years, it can be the cause of metabolic issues. Finally, white sugar is not worse than the brown one: the only reason to prefer the latter is your personal taste.

2. “Eating eggs will increase your blood cholesterol”

Cholesterol is an organic compound belonging to the family of lipids, and it plays a fundamental role in our metabolism: it is a constituent of cell membranes and a precursor to several hormones, including the sexual hormones. However, hypercholesterolemia (an excess of cholesterol in the blood) can increase the risk of contracting a cardiovascular disease. So, should we avoid foods containing cholesterol in order to keep its blood levels under check? And what about eggs?

As usual, it depends. First of all, it’s worth remembering that 80% of our bodily cholesterol is endogenous in origin, that is, it is produced internally by our liver. Our body is capable of regulating the balance between endogenous and exogenous cholesterol, the latter being introduced through nourishment: the more we eat, the less we produce. However, people suffering from hypercholesterolemia might be affected by an imbalance in exactly this mechanism, and this is where diet becomes important. In these cases, foods rich in saturated fats should be avoided, such as red and cured meats; when possible, the fat parts of foods should be removed, such as in ham and chicken legs.

Eggs contain cholesterol in the yolk, which stores nutrients and particularly fats, while the egg white consists mainly of proteins. However, this cholesterol is largely unavailable from a nutritional point of view, especially when the yolk is well cooked, due to the action of lecithin. Therefore, eggs are less “dangerous” than other fat foods for people suffering from hypercholesterolemia, and they are not at all so for anyone with normal blood values. Eggs can be eaten even everyday, as long as they are well cooked, and blood tests keep coming back ok!

3. “Red wine is healthy”

Wine is an alcoholic beverage obtained from the fermentation of grapes. It may contain 70–90% water, 9–16% ethyl alcohol (or ethanol), and other components in small quantities. Wine, particularly the red kind, also contains resveratrol, a molecule synthesized by plants as an antifungal which also exhibits antioxidant properties in humans, providing antitumoral activity and protection to the cardiovascular system. Unfortunately, resveratrol is also poorly soluble, leading to low bioavailability. Some studies have shown that, in order to reach a resveratrol dosage with significant biological effects, we should drink 4 liters of red wine per day.

Obviously, this isn’t feasible. A bottle of red wine contains a few milligrams of resveratrol, while it contains approximately ten grams of alcohol on average. The benefits deriving from the antioxidant substance would be immediately canceled by an extremely toxic quantity of ethanol.

How toxic is ethanol, by the way? What is a safe dosage we can consume with no unpleasant consequences?

Alcohol directly affects the neuroendocrine system through interaction with the opioid and serotonin receptors: this causes the known pleasurable feelings of sedation and euphoria. However, chronic consumption leads to addiction and irreversible neurological conditions. The toxic effect on the liver is also very well known and takes place already at low dosages. In addition, the IARC has found a causal connection between alcohol consumption and the development of some cancers, particularly those affecting the digestive trait: mouth, larynx, esophagus, stomach, pancreas, gut, and liver. So far, we know that the correlation is dose-dependent, and no “safe” quantity lowering the risk to zero has been determined.

In conclusion, the negative effects of drinking alcohol are definitely more numerous and serious than the positive ones. Alcohol is literally a drug and a toxic substance. The fact that it is still sold legally depends on its extremely large use rooted in tradition, which makes it socially impossible to outlaw alcoholic beverages at present. Finally, it’s worth noting that resveratrol is present in the skin of grapes and other fruit, such as raspberries: if you wish to take advantage of its beneficial properties, you’ll be much safer eating those fruits.

4. “Palm oil is dangerous”

Palm oil is extracted from the fruits of palm trees. This oil is characterized by the highest production volumes globally, and it is employed in plenty of commercial foods including, but not limited to, cakes and cookies. One reason behind its widespread use is its high stability against degradation owing to the elevated content of saturated fatty acids. Moreover, its production is particularly profitable because the cultivation of palm trees requires a relatively small ground surface compared to the amount of oil produced. As a consequence, palm oil is extremely cheap.

The saturated fatty acid content of palm oil is 45–55% (for a comparison, consider that this is approximately 15% in extra virgin olive oil). This immediately rings a bell: palm oil must be bad for our health! Evidently, saturated fats are not the healthiest, and we should limit their consumption. At the same time, they provide thermal stability to the oil, thereby limiting the risk of degradation during cooking. Indeed, vegetable oils with a high content of polyunsaturated fats (such as sunflower oil) should not be used for prolonged high-temperature cooking procedures, as they degrade and produce acrolein (toxic) and acrylamide (genotoxic and carcinogenic).

But… then, why have we pledged a war against palm oil? Why have so many food companies banned this oil from their products?

The answer is simple. The real reasons behind this so-called war have been, over time, misunderstood and distorted. The real problem with palm oil is its environmental impact: owing to the abovementioned reasons (efficiency and low cost), the extension of palm tree cultivations keeps increasing each year and represents one of the major causes for deforestation in the main producing countries, Indonesia e Malaysia. Unfortunately, the efficiency of palm oil production is such that we haven’t found a suitable replacement yet. Should we replace palm trees by, for example, rapeseed or soy, we would require even larger surfaces for their cultivation, thereby worsening the issue of deforestation.

To sum up, palm oil represents an environmental problem; however, from a nutritional point of view, it’s not so bad as it has been made to look. It’s worth considering that the foods it is usually employed in (snacks, industrial pies, creams…) are not exactly healthy per se, as they provide little nutritional value, while their calorie content is typically very high; therefore, whether they contain palm oil or not, those foods should be avoided, or their consumption limited.

MM

Disclaimer: the information contained is this article is not meant to replace medical advice. If you believe that you might be showing the symptoms of a disease, or if you require nutritional advice, please refer to your physician.


References

WHO Guideline: sugars intake for adults and children.

Hervik, Stein Egil Kolderup, Astrid Kolderup Hervik, and Miranda Thurston. “From science to sensational headline: a critical examination of the “sugar as toxic” narrative.” Food, Culture & Society (2021): 1-15.

Frémont, Lucie. “Biological effects of resveratrol.” Life sciences 66.8 (2000): 663-673.

LoConte, Noelle K., et al. “Alcohol and cancer: a statement of the American Society of Clinical Oncology.” Journal of Clinical Oncology 36.1 (2018): 83-93.

Che Man, Y. B., et al. “Composition and thermal profile of crude palm oil and its products.” Journal of the American oil chemists’ society 76.2 (1999): 237-242.

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