Comparing Food Type Benefits
Choosing which foods to eat can be challenging. Articles and studies declaring this food is good for your heart and that food is a carcinogen abound in health sites, and it can be hard to get a clear understanding of how you should change your diet for long and healthy life.
Let’s look at the basic food types and see how they compare in impact on longevity. Here is the number of years of expected life gained or lost for a 40-year-old man:
Four Food Types for Long Life
When looking at longevity impact, many foods hailed as Superfoods, like blueberries or Brussel sprouts, don’t show more or less life extension than other foods in the same category. What type of food (fruit, legume, etc.) you’re eating is more important than which particular variety, so pick the ones you like in that category.
Four foods are Superfoods–nuts, whole grains, legumes (beans), and fish–that provide the most benefit for long health.
Ounce for ounce, nothing beats the life extension available from eating a small handful of nuts every day. The only downside is that the benefit of nuts is limited, so eating more than that is neither beneficial nor harmful. However, they do pack a lot of calories, so stopping after that first handful is a good idea if you’re watching your waistline.
Whole grains, like healthy breakfast cereals, oatmeal, or whole-grain bread, are the next Superfoods, providing almost three years of life extension at four servings a day. Including whole grains at breakfast is an excellent way to start your day with whole grains. Brown rice, quinoa, or oatmeal bars can help get more whole grains later in the day.
Legumes also provide significant life extension, and the benefits improve linearly with the amount consumed throughout the studies. Good sources of legumes can be hummus, chile bowls made with beans, edamame, or bean salad. In Japan, fermented soybeans, called natto, are another option, although the pungent smell and stringy texture may be challenging.
Fish extend life up to three servings in the studies, and, based on the linear results, those benefits probably extend for more servings as well.
Fruits and vegetables provide longevity benefits, but the benefits are capped at around three servings of vegetables or two and a half servings of fruit per day, with servings over those amounts being neither helpful nor harmful.
Refined grains (white bread, white rice, etc.) and poultry (mostly chicken) fall in the middle for effect on life span. They’re both a reliable source of calories and protein in the case of chicken, but studies have shown they generally don’t extend or shorten lifespan overall. Eating these foods provides the most benefit when consumed as an alternative is something less healthy, like processed meats.
In health research, many effects follow a J-curve for benefits. A little bit is good or neutral in effect, but as the amount increases, the result turns negative and continues to be more harmful. Both dairy and eggs follow this pattern. Half a serving or less for eggs has no impact on mortality, but one serving or more per day shortens life, and each serving after that linearly increases the reduction in life span. Likewise, for dairy foods (milk, cheese, ice cream), up to two servings per day is fine, but the third serving reduces lifespan by a small amount and continues each serving after that.
Surprisingly, the adverse effects of four servings of dairy are minor compared to four servings of eggs. Protein is about the same, with an egg having about 27 calories of protein vs. 31 calories for a cup of milk. Perhaps the body can’t handle the cholesterol in eggs over half an egg per day.
Two Food Types That Shorten Life
Each daily 3-ounce portion of red meat (including pork and lamb) takes almost a year off life expectancy. For comparison, four servings of red meat would shorten life by about as much as eating three servings of vegetables and fruits every day would lengthen life. Therefore, eating in moderation or only on special occasions is a good approach for these foods.
The big loser for longevity is processed meat–meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavor or improve preservation. Deli meats, including sliced turkey or ham, are also considered processed meats. The World Health Organization (WHO) categorized processed meats as “carcinogenic to humans (Group 1),” which includes other known carcinogens like smoking or asbestos. Despite the typically smaller serving sizes of processed meats, a sausage half the weight of a 3-ounce hamburger would shorten life by a third of a year more. Ouch.
Cancer isn’t the whole picture, as processed meats are also known to cause cardiovascular issues and type II diabetes.1
When choosing foods, in addition to the type of food, the preparation can also affect the longevity benefits. For example, which is healthier: a hamburger or fried fish? Potato chips or smoked beans? We can use the impacts above to estimate the effects of different foods with different preparation methods.
Common wisdom seems to be that fried foods are bad for you, but this blog is about quantification, so how bad are they? The best study I could find for this was from the BMJ medical journal, which breaks out the impact of eating fried foods on all cause-mortality both by type of food (chicken, fish, other) and serving frequency (<2/months, 2-3/month, >3/month). Unlike most foods that increase mortality, fried foods seem to have a threshold impact level at which they increase mortality and then not as much impact after that. For fried chicken, this threshold is hit at 2-3 servings/month, increases mortality by about 11%, and doesn’t increase much for eating over three times per month.
For fried fish, eating it 2-3 times/month doesn’t seem to have an effect, but over three servings per month increases mortality from all causes by about 7%.
Other fried foods, including french fries, fried potatoes, potato chips, etc., don’t significantly affect mortality. However, since the base of most of those fried foods is potatoes, especially by volume, I would guess the negative impact of fried foods is about as much as the positive impact from vegetables, so that a rough estimate would be about 0.4 years shorter life per daily serving.2
While curing or salting a non-meat food to preserve it isn’t common, smoking can be done for other foods, like smoked nuts or cheese. To estimate the impact of smoking on foods, let’s start with the impact of processed meat per serving (-0.9 years) and subtract that from the impact of processed meats per serving (-2.4 years), which gives -1.5 years change for smoking food.
So, fried fish (about neutral) is better than a hamburger (-0.6 years/daily serving), and potato chips (about neutral) are better than smoked beans (-2 years/daily serving).
And fried, processed meat (corndogs!) is right out (-2.8 years/daily serving).
Frequently Asked Questions
I care about healthy years, not total lifespan. Will eating the right foods extend my healthy life?
A 2020 study looked at how a healthy diet and other habits affect total lifespan and lifespan free from major chronic diseases (diabetes, cardiovascular diseases, and cancer). In general, they found that healthy habits increase lifespan and the number of healthy years before chronic diseases. In particular, for a nutritious diet, the healthiest diet quintile also seemed to reduce the chronic disease years, providing a total of over four years of additional healthy life expectancy compared to the lowest quintile.3
Can I calculate how many minutes of life I gain (or lose) by food type serving per day?
I’m so glad you asked. Yes, the yearly figures in the chart above can be calculated into minutes of life expectancy gained or lost for each meal. For example, since the chart above is for a 40-year-old man, who has a life expectancy of 78 years, he would live an additional 38 years. So a half-ounce of nuts adds 1.9/38 = 5% to his expected lifespan. Putting that into minutes/day, it’s 24 hours * 60 minutes/day * 5% = 72 minutes of additional life per daily serving of nuts.
If half an ounce of nuts gives an extra 72 minutes per day, then eating ten ounces would provide an additional 24 hours life expectancy every day, and I’ll live forever?
I’m afraid the benefits of nuts stop after half an ounce per day.
But the benefits of whole grains should continue even after four ounces per day, so if I eat three pounds per day, I’ll be immortal, right? And if I add three quarts of legumes, I’ll start aging backward and have a true age in my twenties by the time I’m seventy!
I… It doesn’t work that way.
Are you sure?
Interesting figures, but I’m not a 40-year-old man. So how do I find out how my diet impacts my expected lifespan?
Again, so glad you asked. Use the True Age Calculator to adjust the figures for your own life.