Cancer Prevention: The American Cancer Society Guidelines on Diet and Exercise

How can you reduce your risk of cancer through your lifestyle? These guidelines from the American Cancer Society summarize the current scientific knowledge. The article explains why a healthy body weight is so important, what role exercise plays and what specific dietary recommendations there are, such as limiting the consumption of red meat.

 

At a glance

 

This paper presents the updated American Cancer Society (ACS) guidelines for nutrition and physical activity for cancer prevention. These recommendations are based on the latest scientific findings and are intended to help you significantly reduce your risk of cancer. A significant proportion of cancer deaths in the United States are attributed to dietary habits, lack of physical activity, and overweight and obesity, highlighting the importance of these factors.

 

The guidelines advise you to maintain a healthy weight, maintain an active lifestyle and follow a plant-based diet, while consuming processed and red meats and alcohol in moderation. It is emphasized that individual decisions must be made in a supportive social and physical environment and recommendations for collective action are also provided. These comprehensive recommendations are consistent with those for preventing cardiovascular disease and diabetes and promote overall health.

 

The ACS 4+1 Formula: An Evidence-Based Guide to Cancer Prevention

 

The American Cancer Society (ACS) publishes its Nutrition and Physical Activity Guidelines to provide a foundation for the organization's communications, policy, and community strategies, ultimately influencing diet and physical activity patterns in the United States. These guidelines, which are updated approximately every five years, are based on a synthesis of current scientific evidence. It is developed by a national panel of experts from the fields of cancer research, prevention, epidemiology, public health and politics.

 

It is estimated that over 500,000 cancer deaths occur annually in the United States. After quitting tobacco, weight control, diet and physical activity are among the most important modifiable factors influencing cancer risk. Available evidence suggests that about a third of these cancer deaths are due to diet and exercise habits, including overweight and obesity.

 

The ACS guidelines include four key recommendations for individual decisions aimed at reducing the risk of cancer and one key recommendation for collective action (see Table 1 of the original document):

 

Recommendations for individuals:

 

Maintain a healthy weight for life. 2. Maintain a physically active lifestyle. 3. Eat a healthy diet with an emphasis on plant sources. 4. Consume alcoholic beverages only to a limited extent, if at all.

 

Recommendation for the community:

 

Public, private and community organizations should work to create social and physical environments that promote and maintain healthy eating and physical activity habits. This includes improving access to healthy foods in schools, workplaces and communities, as well as providing safe, pleasant and accessible environments for physical activity in schools, transport and recreation.

 

These recommendations are based on the totality of available evidence, including both observational human studies and laboratory experiments. The evidence from prospective cohort studies was given greater weight than that from case-control studies, particularly when results from multiple cohorts were available. Research in the area of ​​nutrition and chronic diseases is methodologically complex. For example, randomized controlled trials (RCTs), often considered the gold standard, may fail to demonstrate effects if interventions begin too late in life, are too small in scale, or follow-up is too short.

 

Many important questions about diet, physical activity and obesity in relation to cancer cannot currently be examined by RCTs, for example due to ethical or practical limitations of long-term weight loss interventions.

 

The guidelines are also consistent with those of the American Heart Association and the American Diabetes Association for the prevention of cardiovascular disease and diabetes, as well as the U.S. Department of Health and Human Services' 2005 Dietary Guidelines for Americans. Importantly, these guidelines show a reduced likelihood of disease occurrence, but do not guarantee complete protection.

 

Weight control as a cornerstone: The connection between BMI and cancer risk

 

The ACS's first recommendation for you is to maintain a healthy body weight throughout your life, which can make a significant contribution to cancer prevention. To achieve this, it is crucial to balance calorie intake with physical activity and avoid excessive weight gain. If you are already overweight or obese, it is recommended that you achieve and maintain a healthy weight.

 

A measure of a healthy weight is the body mass index (BMI), which is calculated from your body weight in kilograms divided by the square of your height in meters (kg/m²). Although the exact limits for a healthy weight are to some extent arbitrary, experts define a BMI between 18.5 and 25.0 as healthy, a BMI of 25.0 to 29.9 as overweight, and a BMI of 30.0 or higher as obese (see Table 2 of the original document for a detailed breakdown by height and weight).

 

In the United States, overweight and obesity—obesity, a state of being severely overweight with a BMI of 30 or higher—are estimated to contribute to 14% to 20% of all cancer-related deaths. Scientific evidence shows a clear connection between overweight and obesity and an increased risk of various types of cancer. These include breast cancer in postmenopausal women, colon cancer, uterine cancer (endometrial cancer), adenocarcinoma of the esophagus and kidney cancer.

 

In addition, there is strong evidence that being overweight also increases the risk of pancreatic, gallbladder, thyroid, ovarian and cervical cancers, as well as multiple myeloma, Hodgkin's lymphoma and aggressive prostate cancer.

 

The underlying mechanisms by which obesity affects cancer risk are diverse and include effects on fat and sugar metabolism, immune function, and levels of various hormones such as insulin and estradiol. Factors that regulate cell proliferation and growth, such as insulin-like growth factor 1 (IGF-1), also play a role. Proteins such as sex hormone-binding globulin, which makes hormones more or less available in the tissue, are also affected. In particular, obesity may increase the risk of esophageal adenocarcinoma by increasing the risk of gastroesophageal reflux disease and Barrett's esophagus.

 

Recent studies suggest that intentional weight loss may reduce the risk of breast cancer and improve insulin sensitivity and biochemical measures of hormone metabolism. Although knowledge about the connection between weight loss and cancer risk is still incomplete, if you are overweight or obese, you should be supported in your weight loss efforts.

 

For weight control, it is advisable to reduce calorie intake by reducing portion sizes (see Table 3 of the original document for standard portion sizes) and limiting consumption of high-calorie foods and beverages that provide few nutrients. Reducing 50 to 100 calories per day can prevent gradual weight gain in most adults, while a goal of at least 500 calories per day is common for weight loss programs. To maintain weight loss, 60 to 90 minutes of moderate to vigorous physical activity per day can be helpful.

 

It is important to note that the health of children and adolescents is critically linked to the establishment of healthy behaviors in childhood, as obesity in childhood often persists into adulthood.

 

Exercise and plant-based nutrition: concrete guidelines for everyday life

 

Beyond just weight control, physical activity is another fundamental pillar of cancer prevention that the American Cancer Society (ACS) sheds light on for you. The ACS's second recommendation encourages you to adopt a physically active lifestyle, and the third encourages you to maintain a healthy diet with an emphasis on plant-based foods. These two aspects are closely linked as they synergistically contribute to maintaining a healthy weight and therefore influence the risk of cancer.

 

For adults, the ACS recommends engaging in 30 minutes or more of moderate to vigorous physical activity beyond usual daily activities at least five days per week. A higher goal of 45 to 60 minutes of targeted physical activity is even more desirable. Children and adolescents should engage in at least 60 minutes of moderate to vigorous physical activity each day, at least five days per week.

 

The physical activities you do can be divided into two categories: “usual” and “targeted” activities. Common activities are part of your daily life, such as going to work, climbing stairs or doing household chores. They are often of low intensity and short duration. Targeted activities, on the other hand, are consciously integrated into leisure time, such as cycling, running or sports. These can take place in the garden, at work, with friends or family.

 

Moderate activities require effort comparable to a brisk walk, while vigorous activities engage large muscle groups and noticeably increase heart rate and breathing (see Table 4 of the original document for detailed examples).

 

Scientific studies show that physical activity can reduce the risk of several types of cancer, including breast, colon, prostate and uterine cancer (endometrial cancer). Even if the evidence for many other types of cancer is still limited, there are some connections. The positive effects of activity arise in many ways: it not only supports a healthy body weight by balancing calorie intake with energy consumption, but also directly and indirectly influences the progression of cancer risk. These include regulating sex hormones, insulin, prostaglandins and strengthening the immune system.

 

The positive effects of an active lifestyle go far beyond cancer prevention and also reduce the risk of other chronic diseases such as cardiovascular disease, diabetes and osteoporosis.

 

Although the optimal intensity, duration and frequency of activity for cancer risk reduction is not yet fully known, the data collected suggests that as little as 30 minutes on most days is beneficial, and 45 to 60 minutes may be optimal for reducing colorectal and breast cancer risks. For people who are still inactive or just starting a program, gradually increasing to 30 minutes of moderate activity most days provides significant cardiovascular benefits. If you're already active for 30 minutes, you should aim for 60 minutes most days.

 

Men over 40 and women over 50, as well as those with chronic medical conditions, should consult a doctor before beginning an intensive activity program.

 

In the area of ​​nutrition, the third recommendation focuses on consuming a healthy diet rich in plant sources. It is recommended to choose foods and drinks in quantities that will help you achieve and maintain a healthy weight. Familiarize yourself with standard serving sizes (as shown in Table 3 of the original document) and read food labels to become aware of the actual amounts consumed. Reduce portion sizes of high-calorie foods. It's important to understand that "low fat" or "fat free" is not the same as "low calorie."

 

Replace high-calorie foods and drinks such as French fries, cheeseburgers, pizza, ice cream, donuts, other sweets and sodas with vegetables, fruits, whole grains, beans and lower calorie drinks.

 

You should eat five or more servings of a variety of vegetables and fruits every day, incorporating them into every meal and as a snack. Avoid fried vegetable products such as French fries and chips, and when drinking juices, choose 100% fruit or vegetable juices. Choose whole grains over processed (refined) grain products. This means you should choose whole-grain rice, whole-grain bread, whole-grain pastas and cereals, and limit your consumption of refined carbohydrates, such as pastries, sweetened cereals and other foods high in sugar.

 

Additionally, you should limit your consumption of processed and red meat. Instead, choose fish, poultry or beans as an alternative to beef, pork and lamb. If you eat meat, choose lean cuts and smaller portions. Prepare meat by baking, roasting, or poaching rather than frying or grilling it.

 

Plant foods such as vegetables and fruits are complex and contain numerous potentially beneficial vitamins, minerals, fiber, carotenoids and other bioactive substances called phytochemicals. These compounds, such as flavonoids, terpenes, sterols and indoles, may contribute to cancer prevention. Increased consumption of vegetables and fruits is associated with a reduced risk of lung, esophageal, stomach and colon cancer. The totality of evidence strongly supports risk reduction through plant-based foods.

 

However, studies of dietary supplements that isolate individual nutrients in high doses have often been unsuccessful or even harmful because the complex interactions of the substances cannot be replicated in whole foods. It's important to encourage consumption of low-calorie, whole vegetables and fruits, especially when they replace higher-calorie foods.

 

Whole grains such as wheat, rice, oats and barley are also an important part of a healthy diet. They are relatively low in calories and can help maintain energy balance. In addition, they are richer in fiber, certain vitamins and minerals than processed grain products. Foods rich in fiber are associated with a lower risk of chronic diseases such as diabetes, cardiovascular disease and diverticulitis.

 

For red and processed meats (such as beef, pork, lamb, sausages, bacon), many epidemiological studies support an association with an increased risk of colon cancer and possibly also prostate cancer. This is attributed to various mechanisms: mutagens and carcinogens can be formed at high cooking temperatures, heme iron can form free radicals, and nitrites/nitrates in processed meat can contribute to the formation of carcinogenic nitrosamines. The fat content in meat could also play a role by increasing the concentration of secondary bile acids. Nevertheless, meat products are important sources of protein and nutrients. Therefore, you should choose lean pieces in smaller portions and pay attention to gentle preparation methods.

 

Research on nutrition and cancer is complex because individual nutrients or foods do not work in isolation. Many nutritional factors and lifestyle practices correlate with each other; for example, people who consume a lot of fruits and vegetables often eat less meat and are more physically active. Therefore, the totality of dietary and lifestyle patterns is crucial.

 

Alcohol as a risk factor: Clear limits and special warnings

 

The American Cancer Society's fourth recommendation addresses the consumption of alcoholic beverages and sets clear limits. You should limit alcohol consumption to a maximum of one drink per day for women and two drinks per day for men. A “drink” is specifically defined as 12 ounces (approximately 355 ml) of beer, 5 ounces (approximately 148 ml) of wine or 1.5 ounces (approximately 44 ml) of 80 proof spirits.

 

The paper notes that alcohol consumption is an established cause of several types of cancer, including mouth, pharynx, larynx, esophagus and liver cancer. For each of these cancers, the risk increases significantly if more than two drinks are consumed per day. A particularly strong risk-increasing effect occurs when alcohol is consumed in combination with tobacco, which increases the likelihood of mouth, throat and esophageal cancer significantly beyond the individual effects.

 

In addition, there is extensive evidence that alcohol consumption is also a cause of breast cancer and probably also influences colon and rectal cancer. In women, regular consumption of more than one drink per day is associated with an increased risk of breast cancer. The exact mechanism for this is not yet fully understood, but could be due to an increase in circulating estrogens or other hormones, a reduction in folic acid levels, or direct effects of alcohol or its metabolites on breast tissue. Women with low folic acid intake may be particularly vulnerable to the link between alcohol and breast cancer. Therefore, women at high risk of breast cancer should consider abstinence from alcohol.

 

For adults who do not currently consume alcohol, there is no compelling reason to start drinking to reduce the risk of heart disease. Cardiovascular risks can be reduced more effectively through other measures such as quitting smoking, eating a low-fat diet, maintaining a healthy weight, and regular physical activity.

 

Certain groups of people should avoid alcohol altogether, including children and adolescents; People of all ages who cannot limit their consumption to moderate amounts or who have a family history of alcoholism; pregnant women or women who may become pregnant; People who want to drive or operate machines or take part in other activities that require attention, dexterity or coordination; and people taking prescription or over-the-counter medications that may interact with alcohol.

 

Risk profiles for specific cancer types: What the data says for breast, colon and prostate cancer

 

Now that you know the general healthy lifestyle recommendations for cancer prevention, let's dive deeper into the specific risk profiles for individual cancer types, as certain behaviors can have different effects. The evidence-based connections between lifestyle factors and the risk of common types of cancer are examined in detail.

 

Breast cancer in postmenopausal women

 

For breast cancer in postmenopausal women, data from the American Cancer Society Guidelines show consistent evidence: increased body weight and weight gain in adulthood are clearly associated with an increased risk. This connection is likely explained by higher levels of estrogen produced in excess fat tissue after menopause. Interestingly, this adverse effect of weight gain may be masked when women receive hormone replacement therapy. Alcohol consumption is also a known risk factor, with the risk being particularly high when folic acid intake is low.

 

Conversely, moderate to intense physical activity has been shown to reduce the risk of breast cancer in postmenopausal women. However, studies that examined very low fat intake showed only a very small effect on risk, such as the Women's Health Initiative Randomized Controlled Dietary Modification Trial. Therefore, the best nutritional recommendation to reduce breast cancer risk is to engage in 45 to 60 minutes of moderate to vigorous physical activity five or more days per week, minimize lifetime weight gain, and avoid or limit alcohol consumption.

 

Colon cancer (colorectal cancer)

 

Colorectal cancer is the second leading cause of cancer-related death among American men and women. The risk of this type of cancer increases with family history, long-term tobacco use, possibly excessive alcohol consumption and obesity, although the association appears to be stronger in men. Low physical activity also increases the risk, whereas moderate regular activity reduces the risk; There is even evidence that more intense activity can provide even greater benefits. A diet high in processed and/or red meat is also linked to an increased risk of colon cancer. In contrast, higher intake of fruits and vegetables is associated with reduced risk.

 

There is supporting evidence for calcium in a protective role against colon cancer or its precursors, adenomatous polyps. However, it is important to note that while aspirin or nonsteroidal anti-inflammatory drugs and postmenopausal hormone therapy may reduce the risk, they are not recommended for prevention due to potential side effects.

 

The best recommendation for reducing the risk of colorectal cancer includes increasing the intensity and duration of physical activity, limiting red and processed meat intake, consuming recommended amounts of calcium (although with the caveat that men should not consume more than 1,500 mg/day due to a possible risk of prostate cancer), consuming more fruits and vegetables, avoiding obesity, and limiting alcohol consumption. It is also crucial to follow the ACS recommendations for regular colon cancer screening.

 

Cancer of the lining of the uterus (endometrial carcinoma)

 

Endometrial cancer is the most common gynecologic cancer in the United States. The etiology of the tumor is complex, with epidemiological and clinical findings distinguishing two types: type I, which is hormonal and has a better prognosis, and type II, which is not hormonal and the causes of which are largely unknown. For type I, there is strong evidence that obesity increases the risk. In premenopausal women this is attributed to insulin resistance and increased ovarian androgens, while in postmenopausal women the increased conversion of androstenedione to estrone in adipose tissue plays a role. Physical activity, in turn, appears to reduce the risk of endometrial cancer.

 

In terms of diet, it is believed that high intake of vegetables and fiber may reduce the risk, while red meat, saturated and animal fats may increase the risk. Therefore, the best strategy to reduce risk is to maintain a healthy weight through a plant-based diet and regular physical activity.

 

Lung cancer

 

When it comes to lung cancer, the situation is clear: more than 85% of cases are due to tobacco smoking, and another 10% to 14% are due to exposure to radon. High intake of fruits and vegetables (five or more servings daily) is associated with a lower risk of lung cancer, particularly fruit consumption. However, there is an important warning: High-dose beta-carotene supplements have been shown to increase, rather than reduce, the risk of lung cancer in smokers in clinical studies. The most effective prevention is therefore to avoid tobacco consumption, avoid passive smoking and radon exposure, and eat at least five portions of fruit and vegetables every day.

 

Prostate cancer

 

Prostate cancer is the most common cancer in American men, but the role of dietary factors remains uncertain. Some studies suggest that a diet rich in certain vegetables (tomatoes, cruciferous vegetables, soy, beans, other legumes) or fish may reduce the risk. Specific antioxidant nutrients such as vitamin E, selenium, beta-carotene and lycopene are also discussed, although clinical studies are still ongoing. However, increased consumption of red meat or dairy products could be associated with an increased risk.

 

A particularly critical warning from the paper relates to calcium: high calcium intake, particularly through supplements, is associated with an increased risk of more aggressive prostate cancers. Therefore, men should limit their calcium intake to less than 1,500 mg per day until further studies are available. Obesity is inconsistently associated with the development of prostate cancer but is associated with a poorer prognosis after diagnosis and treatment. Vigorous physical activity may also provide some benefit.

 

The best recommendation for reducing prostate cancer risk includes eating at least five servings of a wide variety of fruits and vegetables daily, limiting your intake of red meat and dairy products, leading an active lifestyle, and maintaining a healthy weight.

 

Stomach cancer

 

Stomach cancer is the fourth most common cancer worldwide, but is comparatively rare in the United States. A high intake of fresh fruits and vegetables is associated with a reduced risk, while consumption of highly salted foods increases the risk. Chronic infection with the bacterium Helicobacter pylori is also a known risk factor. The increase in the incidence of gastric cancer in the area of ​​the stomach opening (cardia), close to the esophagus, is associated with abdominal obesity and associated reflux. The guidelines therefore recommend eating at least five portions of fruit and vegetables daily, reducing the consumption of salt-cured foods and maintaining a healthy weight.

 

Upper Aerodigestive Tract Cancers

 

Cancers of the upper digestive and respiratory tract, such as mouth, pharynx, larynx and esophagus, are significantly more common among men in the United States. Tobacco in any form (cigarettes, chewing tobacco, snuff) and alcohol, especially in combination, significantly increase the risk. Obesity increases the risk of adenocarcinomas of the lower part of the esophagus and stomach, probably due to acid-induced reflux. Consuming very hot foods and drinks could also increase the risk of thermal injury. However, adequate intake of fruits and vegetables is likely to reduce the risk.

 

The primary recommendation is therefore to avoid tobacco, limit alcohol consumption, avoid obesity and consume at least five servings of a variety of fruits and vegetables daily.

 

Rare or inconsistent findings

 

There are currently no known nutritional risk factors for brain tumors and leukemia/lymphomas. Obesity is a clear risk factor for kidney cancer, and tobacco smoking also plays a role. However, evidence for specific dietary factors is limited or conflicting. The findings for ovarian cancer are still inconsistent. Although genetic and hormonal factors play a role, there are currently no established dietary risk factors. Some studies have suggested a small reduced risk with moderate alcohol consumption, while the association with obesity and physical activity remains unclear.

 

Tobacco smoking, diabetes and glucose intolerance are established risk factors for pancreatic cancer. Although some studies associate obesity, physical inactivity, and high red meat consumption with increased risk, and fruits and vegetables suggest reduced risk, these associations are not yet firmly established.

 

Myths and Facts: What Science Says About Supplements, Soy, and Organic Foods

 

If you're wondering what role supplements and specific food categories like soy or organic play in cancer prevention, the American Cancer Society's guidelines provide precise answers that often differ from common assumptions.

 

Basically, existing evidence shows that a diet rich in vegetables, fruits and other plant foods can reduce the risk of cancer. However, there is currently no evidence that supplements in pill or powder form can reduce the risk of cancer. In fact, some evidence suggests that high-dose supplements may even increase the risk. Because many healthy compounds in vegetables and fruits work synergistically and whole foods contain unidentified components, a dietary supplement cannot replace the full nutritional values ​​of fruits and vegetables.

 

Supplements are primarily intended for people with certain nutritional deficiencies or special needs, such as pregnant women or people with limited nutrient intake, and should then be balanced and contain no more than 100% of the daily requirement for most nutrients.

 

A well-known example of the risks of supplements is beta-carotene: although it is found in vegetables and fruits and has been attributed a protective role, three large clinical trials (RCTs) showed that high-dose beta-carotene supplements increased the risk of lung cancer in smokers rather than reducing it. Research suggests that beta-carotene in foods may be just a marker for other beneficial nutrients, and high doses of a single nutrient in isolation may be harmful.

 

The evidence for vitamin E is also contradictory. Alpha-tocopherol, the most active form of vitamin E in humans, is a powerful antioxidant. While a reduction in prostate cancer risk was observed in male smokers in the alpha-tocopherol beta-carotene (ATBC) study, this association was not confirmed in a later follow-up study (HOPE-TOO) or in two large prospective observational studies. The initial positive results may be due to chance, and hope for alpha-tocopherol as a cancer preventative is fading.

 

Animal studies indicate a potential protective effect against cancer for the trace element selenium, and an experimental study showed initial evidence of a risk reduction in lung, colon and prostate cancer. However, further well-controlled studies are required. An important safety note is that selenium has a narrow therapeutic window; there is only a small margin between a safe and a toxic dose. Therefore, a maximum dose of 200 micrograms per day in a supplement is not exceeded.

 

In the case of soy products, animal studies indicate a protective effect against hormone-dependent cancers due to certain phytochemicals contained in them, so-called phytochemicals, which may have weak estrogenic activity. However, data supporting a protective effect of soy supplements on cancer risk in humans are limited. High doses of soy supplements could potentially influence the risk of estrogen-dependent cancers, such as breast or uterine cancer. Breast cancer survivors should only consume soy foods in moderate amounts as part of a healthy plant-based diet and avoid consuming highly concentrated soy extracts or pills.

 

Artificial sweeteners such as aspartame and saccharin are also the subject of common questions. Aspartame, which is about 200 times sweeter than sugar, and saccharin have not been shown to increase the risk of cancer, according to current evidence. Although saccharin causes bladder stones in rats at high doses, which can lead to bladder cancer, this has not been observed in humans.

 

When it comes to organic foods, there is currently no research that shows that foods labeled as “organic” and grown without pesticides or genetic modifications are more effective at reducing the risk of cancer than conventionally produced foods.

 

Calcium is another nutrient whose role in cancer is complex. Some studies suggest that calcium-rich foods may reduce the risk of colon cancer, and calcium supplements showed a moderate reduction in the formation of colorectal adenomas (precursors to colon cancer). At the same time, however, there is also evidence that high calcium intake, particularly through supplements, may be associated with an increased risk of more aggressive prostate cancers. The recommended daily amounts of calcium are 1,000 mg for people aged 19 to 50 and 1,200 mg for people over 50. You should get calcium primarily from dietary sources, especially low-fat dairy products and green leafy vegetables.

 

In summary, science emphasizes the importance of a balanced diet rich in plant-based foods, but warns against the uncritical use of dietary supplements, especially in high doses, as they may pose unexpected risks.

 

Conclusion: The limits of evidence and the crucial role of community

 

With these guidelines, based on a comprehensive evidence review, the American Cancer Society (ACS) has demonstrated that four individual recommendations and a basic community requirement are the key factors influencing cancer risk after eliminating tobacco use as the largest modifiable risk factor. The guidelines highlight that one-third of the more than 500,000 annual cancer deaths in the U.S. are linked to diet and exercise habits, including overweight and obesity.

 

The core message of the guidelines is that there is no single “miracle pill” or isolated “superfoods” that remarkably prevent cancer. Rather, the overall picture of a healthy lifestyle is crucial. You learned that the recommendations are based on the totality of available scientific evidence, taking into account the methodological challenges of nutritional research. This research is extremely complex because factors such as dose, timing, duration of exposure and individual diets are difficult to isolate and measure in human populations.

 

Many findings therefore come from observational studies such as cohort and case-control studies, as long-term, randomized controlled trials (RCTs) would often be unethical, impractical or simply too expensive.

 

A striking example of the difficulties and controversies in research are the failed beta-carotene studies: although observational studies suggested possible protection against lung cancer, clinical trials with high-dose beta-carotene supplements in smokers showed an increase in risk. This highlights that taking individual nutrients in high doses can be harmful and the complex synergistic effects of nutrients in whole foods cannot be replaced by supplements. Similar caution should be exercised with other supplements, such as selenium, which can be toxic in high doses and whose therapeutic window is narrow.

 

A key perspective of the guidelines relates to the recommendation for collective action: you as an individual make the decisions about your lifestyle, but these decisions are significantly influenced by your social and physical environment. The guidelines emphasize that a supportive environment is essential so that all people have genuine opportunities to make healthy behavior choices.

 

The paper draws an important comparison to successful tobacco control in the United States: While initial educational campaigns resulted in only a gradual decline in smoking, it was not until comprehensive, community-wide policy interventions beginning in the mid-1980s that significant behavioral changes occurred. These included advertising restrictions, price increases through taxes, smoking bans in public spaces and access restrictions for children. The ACS concludes that similar policy approaches and strategies are needed at the community level to promote healthy eating and physical activity across the population.

 

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Originaldokument: CA A Cancer J Clinicians - September October 2006 - Kushi - American Cancer Society Guidelines on Nutrition and Physical.pdf