Written on 04 March 2019.

Nutritionally poor diets increase your cancer risk

- but specific nutrients protect you

People, who eat nutrient-depleted diets, have an increased risk of contracting cancer, according to a French study that is published in PLoS Medicine. The scientists therefore recommend labeling food to help consumers make healthier choices. In the Nordic countries, we already have the “Keyhole label” on certain healthy food items, but even if you follow the official dietary guidelines, it may be difficult to get enough vitamin D and selenium, both of which are nutrients with several anti-cancer mechanisms.

One in three Danes gets cancer, and the curve has not been broken, on the contrary. Because diet plays such a great role, the British health authorities have introduced a special diet index (FSAm-NPS) that ranks food by its lack of nutrients. The higher the score, the lower their nutritional value. Mélenie Deschasaux and her team of researchers from the French Institute of Health and Medical Research in collaboration with WHO have used this system in their new study, and they see it as a potential tool for helping people make the right food choices, thereby lowering their cancer risk.

Nutritionally poor food increases the risk of most cancers

Mélanie Deschasaux and her colleagues analyzed data concerning food intake and cancer occurrence among 471,495 adults during the period 1992-2014. The data was gathered from a large European population study (EPIC). According to the study, 49,794 cases of cancer (primarily breast, prostate and colon cancer) were detected during that period. The scientists rated the diets of the participants using the special FSAm-NPS dietary index to see what types of food gave the highest risk of cancer.
They found a statistically significant relation between a high score (indicating that the food lacked nutrients) and an increased risk of breast cancer in menopausal women. Also, these foods increased the risk of cancer in the liver, colon, rectum, stomach, and lungs.
However, the study was limited by the fact that people’s food intake was self-reported and therefore not very accurate. Still, Mélanie Deschasaux believes that the study is sufficiently reliable to advocate for a better health policy, one where food items are labeled to show their content (or lack of) of nutrients.

Keyhole-labeling is useful – but not for cancer prevention

Denmark, Norway, and Sweden have introduced the so-called Keyhole label to help guide consumers to healthier food choices. The Keyhole concept, which food manufacturers can sign up for voluntarily, requires that foods meet certain requirements in terms of ingredient health. Only food that contributes to a healthy and balanced diet is eligible for this labeling system. In other words, candy, soft drinks, chips, and similar unhealthy foods are not included.
Unfortunately, cancer also affects those people, who follow the official dietary guidelines and stick with Keyhole-labeled foods. Apparently, it is difficult to get sufficient amounts of vitamin D and selenium from the diet, and these two nutrients have anti-cancer mechanisms.

Lack of vitamin D increases the risk of cancer and early death by 30-40 percent

The summer sun is our primary source of vitamin D, yet vitamin D deficiency has become an increasingly common problem over the past decades due to people spending too much time indoors, overusing sun factor cream, and taking cholesterol-lowering drugs (that block the body’s vitamin D synthesis). Moreover, older people, diabetics, and dark-skinned individuals do not synthesize vitamin D as effectively as others do.
Low blood levels of vitamin D increase the risk of several cancer forms and premature death by up to 30-40 percent, according to a large Danish study that is published in the British Medical Journal.

Blood levels of vitamin D are determining for prevention

On the other hand, having high levels of vitamin D in the blood can lower the risk of several cancer forms, which was shown in a large study of Japanese adults. Over the past decades, numerous studies have revealed that vitamin D plays a role in the prevention of breast cancer, colon cancer, and several other cancer forms. It appears that we need a higher intake of the nutrient than officially recommended in order to obtain a preventative effect on cancer.

Did you know that women who spend a lot of time in the sun and synthesize more vitamin D are only half as likely to develop breast cancer as those who get less sun?

We need more vitamin D than officially recommended

The official recommendation for daily intake of vitamin D is too low, according to many experts who claim that the recommendations should lie in the range of 30-100 micrograms daily. It is easy to synthesize this amount of vitamin D by exposing your skin to direct sunlight on a bright summer day. The amount of vitamin D that we get from our diets is very limited, so it is a good idea to take a supplement during the winter period or in situations where one is unable to get enough of the nutrient from sun exposure. Vitamin D is lipid-soluble, and the best way to take it is in an oil-based formula in capsules.

Vitamin D inhibits cancer through the following mechanisms:

Controls a number of genetic activities
Blocks the formation of new blood vessels in tumors (angiogenesis)
Causes diseased cells to self-destruct (apoptosis)
Counteracts uncontrolled cell division and metastases
Contributes to a well-functioning immune defense and helps the body destroy cancer cells
Counteracts local inflammation, which occurs in many cancer forms

Even if you eat healthily, it is difficult to get enough selenium

Selenium supports around 30 different selenium-dependent proteins (selenoproteins) that are important for our energy turnover and also serve as antioxidants by protecting cells against oxidative stress and DNA damage.
Selenium is primarily found in fish, shellfish, organ meat, eggs, dairy products, and Brazil nuts. European crops, however, are generally low in selenium, as there are very limited quantities of the nutrient in the agricultural soil. Research has even demonstrated that it is impossible to get enough selenium by eating fish and shellfish five days per week.

Selenium yeast lower cancer mortality by 50 percent

In 1996, Professor Larry C. Clark, an American cancer researcher, published the result of his groundbreaking NPC study (National Prevention of Cancer), showing that supplementation with organic selenium yeast lowered the risk of several cancer forms. In the group of study participants that got selenium yeast, there were:

58 % fewer cases of colorectal cancer
63% fewer cases of prostate cancer
46% fewer cases of lung cancer
A 50% reduction of all-cause cancer mortality

Ever since the study was published (in the Journal of the American Medical Association), other studies have shown that lack of dietary selenium increases the risk of many different cancer forms, and supplementation with selenium yeast has a protective effect.

Selenium also lowers the risk of breast cancer

Large studies have revealed differences in blood levels of selenium in healthy women and breast cancer patients long before the diseases are diagnosed. This knowledge is highly relevant, as cancer often takes many years to develop.

Selenomethionine supplements do not work – and studies are misguiding

The researchers behind the so-called SELECT trial tested supplements of selenium and vitamin E but failed to find a protective effect on cancer. This was partly because they used selenomethionine, which, contrary to selenium yeast, has no documented anti-cancer properties. Moreover, the vitamin E that they used in the study was from a synthetic source. It is therefore misleading to use the SELECT trial as a scientific reference and as leverage for discouraging people from using selenium as part of their cancer prevention strategy. Instead, one should inform consumers that selenomethionine does not appear to have much of an effect and to recommend selenium yeast as a better alternative.

Selenium yeast protects against prostate cancer

A study conducted by scientists at the Technical University of Denmark shows that daily supplementation with 200 micrograms of selenium yeast lowers the risk of prostate cancer. That amount is far higher than the recommended intake level for selenium (55 micrograms in Denmark).

Selenium supplementation is necessary for cancer preveniton

An estimated 20 percent of the Danish population has a dietary selenium intake that is below the reference intake level (RI). However, according to research, even the RI level of 55 micrograms is not sufficient to saturate selenoprotein P, which is an important marker of selenium status in the human body. In order to saturate this selenoprotein properly, one would need to consume 100-125 micrograms of selenium every day, or twice as much as the current recommendations.
When buying selenium preparations, make sure to choose selenium yeast with a blend of different organic selenium species. This is how you get the same variety of selenium compounds as you get from eating a balanced diet with many different selenium sources.

Effective cancer prevention requires an adequate intake of selenium to saturate the different selenoproteins, which have the following functions:

They are powerful antioxidants that protect cells against free radicals
They repair DNA damage
They neutralize mercury and other environmental toxinx
They prevent the formation of new blood vessels in tumors (angiogenesis)
They cause diseased cells to self-destruct (apoptosis)
They contribute to a well-functioning immune system
They counteract inflammation

References

Mélanie Deschasaux et al. Nutritional quality of foods as represented by the FSAm-NPS nutrient profiling system underlying the Nutri-Score label and cancer risk in Europe: Results from the EPIC prospective cohort study. PLOS Medicine 2018

Sanjeev Budhathoki et al. Plasma 25-hydroxyvitamin D concentration and subsequent risk of total and site specific cancers in Japanese population: large case-cohort study within Japan Public Health Center-based Prospective Study cohort. BMJ, 2018

Science News. Higher Vitamin D levels may be linked to lower risk of cancer. ScienceDaily March 2018

Shoaib Afzal et al. Genetically low vitamin D concentration and increased mortality: Mendelian randomization analysis in three large cohorts. BMJ 2015

New Links between selenium and cancer prevention. HRB. December 2017

Clark LC et al: Effects of Selenium Supplementation for Cancer Prevention in Patients with Carcinoma of the Skin. JAMA: 1997.

Klein EA et al. Vitamin E and the risk of prostate cancer: The Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA 2011.

Schrauzer GN, et al. Selenium in the blood of Japanese and American women with and without breast cancer and fibrocystic disease. Jpn J Cancer res. 1985