How Daily Habits Shape Cancer Risk

Number 1 strategy for preventing cancer, avoiding tobacco. Probably the single most impactful step anyone can take to lower their cancer risk. I won't spend a lot of time on that. I think the evidence— and I saw someone in the chat asking about negating the effects of previous smoking. You know, I think the best thing that you do is quit, right? I mean, cigarette smoking is linked to 80 to 90% of all lung cancer deaths in the United States. But even if you have smoked, quitting in early adulthood eliminates about 90% of the excess mortality from smoking, and it's never too late. Quitting later cuts lung cancer risk by about 50% within just 10 to 15 years. So quitting smoking is the best thing that you can do for your health. If you've already done that, you're well on your way.

And then, you know, if you're trying to live your healthiest, best life on top of that, even better, right? So number 2, I would say the next best thing that you can do for cancer prevention honestly is to maintain a healthy body weight. I hate to use BMI because, you know, a lot of muscle mass can kind of skew that BMI towards the high range, which isn't necessarily bad, but let's just, you know, presume that we're just talking about people without a lot of excess muscle. You wanna keep your BMI in around a healthy range between about 18.5 to 24.9. Obesity strongly increases risk for many cancers, like 13 different types of cancer, endometrial, breast cancer, colon cancer, kidney cancer, so many different types of cancer that is linked to obesity.

It's actually estimated that about 11% of cancers in women and 5% of cancers in men are linked to excess body weight. Being overweight or obese is detrimental. Most people are thinking about it in terms of their type 2 diabetes risk and their metabolic syndrome, but, but cancer needs to be on your mind because 50 to 60% of all endometrial cancers in the United States are linked to being overweight or obese. And, about 20% to 60% of postmenopausal women that are overweight or obese have a much higher risk of breast cancer. And, even colorectal cancer, again, that's another one, up to 40% of people have a much higher risk if they have an unhealthy weight. So, even modest weight loss can be very meaningful.

And one of the best ways to lose weight, you want to eat healthier and you want to eat less, move more. And that takes us to the regular physical activity. I mean, exercise is one of the best things you can do for absolutely every aspect of health. I have taken exercise so seriously to the point where sometimes I run myself down a little bit too much because I prioritize it. Just extremely important. It is the most important thing I do each day is getting my exercise. You wanna, you do, if following the guidelines, if you're getting about 150 minutes a week of vigorous-intensity exercise, you're at least doing good. If you can get more of that, even better.

For moderate intensity, if you're getting at least, you know, if you're getting about 300 minutes of moderate-intensity exercise a week, you're doing pretty good. If you can get, if you can mix in some vigorous-intensity exercise in there, even better. So I would say number 4 thing that's great for cancer prevention is eating a healthy diet. Now, what does that mean? I mean, it depends on who you're asking in, in many cases, but I would say it's undeniable and you're not gonna find a study that people, where people who eat vegetables and fruits, they eat nuts and whole grains and legumes, and they limit their processed meat, they eat healthy, you know, poultry and, and, and fish and lean red meat.

Um, I think that those people are— you're like, there's so many studies showing that that kind of diet, more of a Mediterranean type of diet, is associated with greater cancer reduction than, than other diets are. And in some cases, like colon cancer, having a lot of fiber reduces cancer incidence by up to 60%. Very important. And colon cancer is a top one that people get and die from. It's up there in the top 3 or 4. So it's something to really pay attention to. There's just, there's no argument. I know carnivore diet's popular, but there's just no argument that can be made that fiber isn't good for your colon and that it doesn't decrease colorectal cancer risk.

Because it really, for each 10-gram serving per day, it may decrease colorectal cancer risk by 10% for each 10-gram serving. So you go up 10, 10% reduction, you go up 10 more, 10 more percent reduction in colon cancer risk. It just keeps going. And that's why we're getting that number of about 50 to 60% reduction in colon cancer incidence for people that are eating at least 5 servings of fruits and vegetables each day. So, I do think that a healthy diet means fruits and vegetables, and I don't think that you should be as scared of the modest postprandial glycemic response from some fruits. It's modest, it goes down, especially if you're healthy and exercising, and it's not something to really be concerned about. I just— there's just no evidence that eating fruit makes you unhealthy.

In fact, quite the contrary. I would say the biggest thing that you want to avoid is processed meat. You know, there's no— at this point, I'm convinced that processed meat is linked to colorectal cancer. In fact, it's really alarming over the last— if you look at the colorectal cancer incidence dating back to like the 1930s, it keeps rising exponentially each decade, each decade. And what's happening, what's been happening in our diets over the course of these decades is we've really increased our intake of ultra-processed foods. We're taking in these foods that are high in refined sugar, they're low in nutrient, they're high in fat, they're high in calories, high in sodium. And we're taking a lot of these processed meats that have all these preservatives and additives.

And we're eating less whole food. And it truly is reflected in the increased incidence of colorectal cancer. So I think that limiting ultra-processed foods, limiting processed meat will clearly reduce cancer risk. So that is something that I think is really important to consider as well. Number 5, limiting alcohol intake. Less really is better here. Heavy drinkers do face a 5-fold greater risk for mouth and throat cancers, and even moderate drinking, just 1 drink per day, raises breast cancer risk by about 10%, while those who consume 2 to 3 drinks a day have about a 20% higher risk. I covered this in my alcohol podcast. You know, it's, it's, it's pretty clear. I think the evidence is clear now that alcohol increases cancer risk. So doesn't mean you can't ever drink it.

You just have to realize that, you know, if you're do— if it's a habit where you're doing it once a day, that's probably gonna be a problem because it's really gonna dramatic— gonna affect your, your cancer risk. If it's something that you're gonna do once in a while, a couple times a month, I mean, I don't know that that's something so much to be concerned about. Not a lot of evidence showing that really raises cancer risk, but it's this, it's this daily, you know, drinking of alcohol, that's really, it's really just, I would say, something that you can get rid of and it'll be tremendous for lowering cancer risk.

And then there's things like, you know, if you're someone that's outside and runs a lot and you're just really in the sun for long periods of time, you have to really consider, especially if you're living in a place that's getting a lot of ultraviolet radiation, you know, UV radiation's the main cause of skin cancers. No denying that. And the good news is you can protect your skin from UV exposure by a lot of different ways. There was a randomized controlled trial in Australia that showed regular sunscreen use reduced melanoma incidence by 50% over 10 years. That is amazing. No argument there. Sunscreen does reduce the risk of melanoma.

Melanoma is one of those, those skin cancers that's really problematic because it metastasizes quite quickly actually, and people end up dying from, from cancers in other areas. And then there's a lot of environmental exposures, right? So there's air pollution, secondhand smoke, you know, having an air filter I think is something to be, to, to consider as well, 'cause it's gonna filter out some of that particulate matter and things like that. Radon, something you may not be aware of. Radon is an invisible gas. It enters our home through the soil beneath it. It's actually the second leading cause of lung cancer in the United States.

So you can test your house for radon and make sure that you're not living in an area where the soil has high radon levels and it's something that you're breathing in every day, particularly in the wintertime when you have a lot of the doors and windows shut. And so that's also something to consider as well. Stress management, mental health. I mean, stress is linked to cancer. There's a lot of fuzziness into how it's happening, cortisol, high inflammation. It's hard to pin down the exact mechanisms, but there's just observational evidence that stress, chronic stress increases cancer incidence. Essentially through some immune and inflammatory pathways, right? Then there's sleep and circadian rhythm. I mean, this is a very important area.

We know that people who have poor sleep, they're night shift workers, they have a disrupted circadian rhythm, they have a higher cancer risk. In fact, the World Health Organization classifies circadian disruption, shift work, as a probable carcinogen. So prioritizing consistent quality sleep, you wanna make sure you're at least getting 7 to 8 hours nightly to support your immune, immune regulation, to support hormonal regulation. These are very, this is very important. So focusing on sleep's very important for cancer prevention. And then there's supplements. I know a lot of people are interested in supplements as well, and there's a lot of supplements that can have, I would say, plausible mechanisms to help with cancer prevention. Like we've talked about magnesium.

Vitamin D, even sulforaphane. There's only really a few supplements that have had, you know, promising clinical evidence for reducing cancer risk over the past couple of decades. I would say one of those is actually vitamin D. So vitamin D, there's Mendelian randomization studies. Again, these are studies where researchers use genetics to get at a causal role for something in the environment while controlling for a certain outcome. So, in this case, people have SNPs in genes that are related to vitamin D metabolism that make them have genetically low vitamin D levels. Those individuals, so this is completely independent of any other lifestyle activities, right? You could say someone with low vitamin D levels might just be unhealthy. They never go outside.

They don't, you know, they're not getting exercise outside. There's a lot of reverse causation problems when you look at observational data, just directly measuring vitamin D levels and associating it with an outcome. Well, with Mendelian randomization, you're not actually measuring their levels, you're looking at their SNPs, and people with these SNPs have low vitamin D levels. And so what happens is people with those SNPs have a much higher cancer-related mortality, much higher than people without those SNPs. And so, it strengthens the observational data that has also shown people with low vitamin D levels have a higher cancer-related death and incidence. And so, that's where you go, okay, well, the genetically low vitamin D levels really strengthen that.

And so, it seems as though vitamin D may be playing a role in preventing cancer death. There was a very large clinical trial. This was the VITAL study. A secondary analysis of that trial found that vitamin D supplementation, this was 2,000 IUs a day, did lower cancer-related death compared to placebo. So vitamin D's a big one. Magnesium is another one. And it's so, it's so obvious because, you know, half the country of, at least in the United States, half the people in the United States have low magnesium. They're not getting enough magnesium. Same with vitamin D, even more than half the country has low vitamin D. So those are 2 obvious, obviously I would say low-hanging fruits there because people are already sort of deficient or insufficient in them.

And so it helps to take a supplement to get you to that sufficient level. There's also some observational studies showing vitamin C is linked to a lower cancer risk. And again, with the observational studies, it's hard to know. Vitamin C is often packaged with fruits and vegetables. And so— It's likely also that people that are eating a low fruit and vegetable diet have low vitamin C, and therefore, we don't really know if it's the vitamin C or just the whole food itself with all the different micronutrients, not just vitamin C, but other ones like magnesium and vitamin K and calcium, for example. They all may be having an effect.

There's also some interesting data that making sure you're getting enough dietary calcium, we've talked a lot about calcium in these Q&As, but you know, essentially it's best to get your 1,000 milligrams a day as much from your diet as you can. Remember, vegetables are a great source. Dark leafy greens are a great source of calcium. Nuts are a great source of calcium as well. Some dairy, of course, also is a great source of calcium. There's evidence that it seems as though calcium's really good for the colon as well and for preventing colon cancer and particularly these adenomas that are, that form and that are predictive of cancer. So, so that's also something to consider as well. And then there's some supplements that may cause harm.

And this is kind of going back to the question about N-acetylcysteine. You know, the N-acetylcysteine, it's a very potent antioxidant. It's really seem— it seems to be a concern in smokers that are already sort of at a high risk for lung cancer. And that's the same with beta-carotene. So actually taking a really high dose of beta-carotene, 30 milligrams a day, and retinyl palmitate, 25,000 IUs a day, significantly increased lung cancer risk in people with a history of smoking. The risk went up to about 28% higher. And this was a big trial that was done. It was the— in 2004, it was a beta-carotene and retinol efficacy trial. Now, keep in mind, this is people that have already previously smoked, and there's something about the niche in the lungs and the reactive oxygen species in the lungs that the beta-carotene sort of has an effect on. And so, it's one of those things that if you were a former smoker, certainly a current smoker, is something that you do not want to be taking.