Friday, April 20, 2018

Rethinking Fruit

Recently, I was invited to give a lecture on food facts and myths. As usual after such a lecture, many audience questions focused on what is the best diet. After six years of intensive reading, my arguably oversimplified, but most accurate working conclusion is that the healthiest generic diet is for one to eat healthy foods in moderation and avoid unhealthy food.
This is based on a highly researched conclusion.
1.     Given genetic and metabolic differences inherent in all humans, including varying predispositions to diseases like heart disease, cancer, and diabetes, it is challenging to be certain that the consumption of any single food in large quantities, fruits and vegetables included, has any health benefits. The body needs what it needs (natural occurring fats, proteins, vitamins, minerals, water, fiber, and antioxidants) and consumption of anything beyond that appears to serve no benefit no matter who you are.
2.     No study demonstrates that consumption of healthy food, including so called “super” foods, somehow neutralizes your consumption of unhealthy foods.
3.     Caloric restriction diets have decent supportive science. Remember, caloric restriction diets are primarily based on the premise of consuming nutritionally dense healthy food to meet minimal requirements and avoiding calorically-rich unhealthy food. I say the science is decent because populations studied have been limited and such studies need extensive tracking periods and variable control (other variables e.g., exercise, stress, sleep, social determinants of health, etc. also play a role) to generate truly reliable data, and such studies simply don’t exist. (There have been some good primate studies, but not without debate. One major study showed significant health improvement measured by longevity and one did not. Pundits argue that the one that showed benefit included primates that otherwise consumed a traditional human diet, i.e. an unhealthy one. Therefore, the switch to a healthy calorically restricted diet extended life. The second study included primates that already ate a limited healthy diet and further restriction served no benefit. That makes sense as there is a minimum requirement to getting what you need and below that there is also no benefit.)
Now, let’s discuss fruits. For the record and with full transparency, I am historically a huge consumer of fruit – a bona fide card-carrying member of the Fruitopian Society – actually I just made that society up, but you get the idea. What is true is that my affection for watermelon is legendary. Both during the off and on seasons, my watermelon consumption can be mind-boggling. On many an occasion, I have devoured half of a large watermelon in a single sitting. (As an aside my obsession with watermelon stems from positive memories of enjoying its sweetness after many a pleasant date. Its abundance of lycopene, an antioxidant some studies have shown to have benefit against prostate cancer, a not uncommon male affliction that has been spotted in my family, doesn’t hurt.) In addition, I routinely consume a banana and blueberries for breakfast. Various melons, citrus fruits, grapes, cherries, etc. often round out my daily fruit consumption. I choose organic when available for soft skinned fruits and eat regular for the rest.
Despite my embrace of fruit for many a year, I have begun to realize that I have been willfully negligent in applying my own philosophy to eat healthy foods, i.e., fruit, in moderation. Many a nutritionist has been challenged by me to identify why I can’t eat fruits with reckless abandonment. Nutritionists mostly agree fruits are very healthy. However, they also widely agree that diabetics should limit their intake to about 15 grams of fruit (equal to a small piece of whole fruit or about ½ cup of frozen or canned fruit) at any given time. The reason is that studies have shown that fruit does raise blood sugar levels, although by a different mechanism than processed sugar. The amount that a food raises blood sugar is called its glycemic index (GI). Most fruits have a low GI because of the intermingling of their fructose (natural sugar) and fiber content. The natural fiber slows down absorption of the sugar. (That’s why fruit juices, sans fiber, are generally not recommended by nutritionists worried about their patient’s blood sugar and weight gain. Smoothies contain fiber, but they also result in far larger fruit portion consumption and so also violate the eat healthy food in moderation dictum.) Melons and pineapple have medium GI values as do some dried fruits such as dates, raisins, and sweetened cranberries.
Where does that leave us with fruit? Let me answer for myself. Despite an otherwise ridiculously healthy diet, my fasting blood sugar levels maintain a rigid position in the pre-diabetes range as determined by fasting blood sugar levels and my hemoglobin A1C (a blood test that shows your average blood sugar over a few months.) I have been stymied by such results and finally realized my potential error – my oversized fruit consumption. Consequently, I have significantly cut back on fruit for the past few weeks. I still have a banana and blueberries for breakfast, had a few apple slices during the day yesterday and an orange later in the evening; but, my fruit splurging has ended. In eight weeks, I will check my levels again and will report if I finally see an improvement in my blood sugar levels. My confidence is high I will
By the way, in case you are wondering, my blood sugar levels have nothing to do with my weight, which is at high school levels again and well within the normal BMI (measurement of healthy weight) level.
Stay tuned as I report on this experiment of N equals one - me. Meanwhile, as I try to now truly practice what I preach, which is eat healthy foods in moderation and avoid unhealthy food, I implore you to consider doing the same.

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