What is the Nutritional Impact of Cigarette Smoking?

These three nutrients work as antioxidants to help reduce the health risks from smoking.  Not only do they have their own effects on the free radicals from smoking, they also impact each other.

Beta-carotene is converted to vitamin A within the body.  However, smoking lowers the amount of this nutrient in the body by affecting its metabolism – it oxidises the anti-oxidant!  Smokers are advised to AVOID vitamin A (beta-carotene) supplements as it is thought to increase the risk of pneumonia and lung cancer in smokers.  Consuming beta-carotene and vitamin A rich foods is not thought to have these harmful effects.

Vitamin E is a fat-soluble antioxidant, meaning that we need to consume healthy fats to help us absorb it.  Vitamin E is believed to help protect lung tissue, but smokers may have a sub-optimal level in their tissues.  This is because the body focuses on maintaining plasma levels (the amount in the liquid part of blood) of the nutrient instead of tissue levels – the vitamin in the tissues may be drawn out into the plasma.  However, vitamin C can help to reduce the depletion as it helps to recycle vitamin E.  Unfortunately, vitamin C may also be depleted by smoking.

It is thought that smokers require 35mg more vitamin C than non-smokers  The standard recommended intake is 40mg, so smokers require nearly double this recommendation.  Vitamin C has many functions in the body including collagen production as well as helping the fight against free radicals.  Smokers have significantly higher levels of free radicals than non-smokers due to the toxins present in the cigarettes and their smoke.  There have been studies that show even children exposed to second-hand smoke have depleted levels of vitamin C.

I will be doing a short Friday Five series looking at antioxidant nutrients soon – keep an eye out!

Although smoking does not directly deplete our calcium levels, it does reduce our ability to absorb this mineral.  It is thought this happens as a result of disruption of blood circulation within the gut.

Calcium has several roles in the body but is probably best-known for its association with bone health, which is also affected directly by smoking.  Smoking reduces the blood supply to our bones and the nicotine slows down the production of bone-producing cells.  Our – both men and women’s – bones are also affected by oestrogen, which is again affected by smoking.  All of these elements combined, smoking is not helpful to our bone health!

Selenium is a mineral that is important for thyroid health and the immune system.  It is also an antioxidant.  Selenium levels have been found to be lower in smokers than non-smokers; probably due the cadmium they may inhale.  It is thought that cadmium combines with selenium to form a compound, therefore reducing the bioavailability of the selenium.  The inflammatory effects of cadmium may also contribute to selenium depletion.  See the article by Wang et al in the Further Reading box (below) for more information about the health effects of cadmium.

There are several different B vitamins that we need daily for good health.  While the studies I looked at when preparing this article tended to be quite small, there were findings that suggested that these vitamins can be depleted by smoking.  These studies and findings may be used as the basis for future large-scale studies.

In the studies reviewed, the evidence regarding vitamin B12 has shown significant depletion in smokers (one study (Singh) states a 27.9% difference in B12 levels).  This appears to be because of the increased level of cyanide that smokers are exposed to.  We metabolise cyanide and B12 in a similar way.   Therefore it is possible that when our bodies are working to get rid of the toxic substance, the B12 is excreted as well.  As a result more B12 is excreted by smokers than non-smokers.

Vitamin B6 levels have also been found to be lower in smokers.  This means smokers get reduced benefits from this nutrient specifically (such as the production of red blood cells and neurotransmitters), but also this may contribute to the lower folate levels that smokers have.  Vitamin B6 helps us to use folate.  Folate levels could also be reduced by interference with absorption or other utilisation of the nutrient.  The depleted folate levels, may contribute to the DNA-related issues caused by smoking.

Furthermore, there have been studies where findings suggest that nicotine reduces our absorption of thiamine (vitamin B1).  Thiamine helps use to convert food to useful energy, and supports our nervous system.

As with beta-carotene, links have been found between high-dose B6 and B12 supplementation and an increased risk of lung cancer in men who smoke.  It is therefore recommended that smokers AVOID these supplements.

Zinc is a mineral with several roles in the body, including immunity, our sense of smell and DNA repair.  It is thought to reduce the risk of obstructive lung disease.  Unfortunately for smokers, the cadmium in tobacco displaces zinc resulting in smokers having lower levels to support their health.  It is likely that cadmium competes with zinc in terms of wanting to bind to a type of protein called metallothionein.  Cadmium competes with iron in this way too.

Interestingly, while cadmium can contribute to lung disease, it accumulates in the kidneys at significantly higher levels than it does in the lungs.  There is evidence suggesting that this is a risk factor for kidney disease.

• “Cadmium and Cadmium/Zinc Rations and Tobacco-Related Morbidities” – Richter, Faroon and Pappas.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5664655/
• “Effects of Cadmium Exposure on the Immune System and Immunoregulation” – Wang, et al. https://www.frontiersin.org/articles/10.3389/fimmu.2021.695484/full
• “Effect of Cigarette Smoking on Serum Homocysteine and Vitamin B12 Level in Male Population of Udaipur” – Singh.  https://www.longdom.org/open-access/effect-of-cigarette-smoking-on-serum-homocysteine-and-vitamin-b12level-in-male-population-of-udaipur-2161-1009-1000282.pdf
• “Study with Smokers Shows Vitamins Combine for Benefits” – Science Daily.  https://www.sciencedaily.com/releases/2006/02/060224104219.htm#:~:text=The%20new%20study%20is%20one,its%20levels%20in%20the%20blood.