Happy New Year!
It has been some time since I last wrote on this blog. I promise to do better this year. And like many of you, one of my New Year resolutions for 2020 is eating more healthfully and mindfully. But what does that really look like and how am I going to sustain this new habit? At 4:30 pm on New Year’s Eve, while preparing my dish for a potluck dinner celebration with some friends, I read a wonderful article on the New York Times by Melissa Clark. In the Meat-Lover’s Guide to Eating Less Meat, Ms. Clark argued convincingly that reducing meat and dairy intake can help mitigate climate change. Apparently, meat and dairy production alone account for 14.5% of the world’s greenhouse gas emissions annually – as much as cars, planes and ships combined. I was happy that I was just roasting cauliflower for the party that night but that certainly did not absolve my guilt over the 7-pound prime rib that I made for our Christmas dinner. I was so moved by the article that I resolved to go completely vegetarian for two months and maybe I will reintroduce fish or possibly meat back into my diet. I will also double down on my intermittent fasting practice that I started a few months ago but it has been slacking of late, due to the many sweet temptations that paraded through my home and office during the holiday season. When it comes to a commitment of this sort, I found it easier to go all out and then back off a bit. I can endure just about anything for two months, but I love sushi and shellfish so much that I cannot imagine giving them up forever. So, if you are reading this, ask me about my resolution and hold me accountable the next time you see me.
The cardiovascular benefits of a plant-based diet have been pretty well established, as pioneered by Dr. Dean Cornish and other researchers. But what about the eyes? After all, this is the year 20/20. Can a vegetarian diet prevent eye diseases or even improve eyesight? Is there any truth to the old adage that eating carrot is good for your eyes? As usual, mom is right. Carrot is high in beta-carotene, a naturally occurring pigment that is converted into Vitamin A in our intestinal walls. Vitamin A in turn is essential for the normal functioning of the photoreceptor cells in our retina (cones and rods) which transduce light energy into electrical signals that are transmitted to the brain.
Leafy green vegetables such as kale, collard greens and spinach are high in luetin and zeaxanthin, a related class of pigment (Xantophylls) that protect the eyes by filtering out blue light that can damage the central part of the retina to cause macular degeneration. Leafy green vegetables may also offer protection against glaucoma. In a multicenter study of 1155 female (mostly white) 65 years and older, just one serving of collard greens per month decreased the odds of glaucoma risk by 69% when compared to those who consumed less than one serving per month. The same study also found that consuming more than two servings per week of carrot or one serving per week of canned or dried peaches also substantially lower the odds of glaucoma development. I am heading to Trader Joe after writing this article but beware that these findings may not be extrapolated to males, African-American or a younger population.
But if a meat lover eats a sufficient vege side dish, would that be enough for protection against eye disease? Would eliminating meats confer additional eye health benefits? In a study out of England (EPIC -Oxford), a strong and convincing pattern of cataract risk and meat consumption was found. Low meat eaters, defined as less than 50g per day reduce the odds of cataracts risk by 15% compared to high meat eaters, defined as more than 100g per day (which isn’t much by American standard). Fish eaters reduced the odds further to 21%. Vegetarians: 30%. And vegans? A whopping 40%. Studies in the Spanish and Swedish populations similarly found that consuming food rich in antioxidants (fruits, vegetables, wholegrains and coffee) reduce the risk of cataracts. While I know first-hand that the visual outcomes with cataract surgery are excellent and the complication rate is so low, the idea of keeping my own natural lens is still very appealing to me and many patients. Personally, knowing the findings of these studies, I would definitely choose to eat less meat to avoid cataract altogether.
Intermittent fasting is all the craze lately in the health and fitness world. The idea is to restrict one’s caloric intake into specific times of the day or week even though the total calories that are consumed might still be the same. Technically, within reasons, you can eat what you want, ie: no restriction on proteins, carbohydrates etc. The most popular regimen is the 16/8 program in which all the day’s eating is confined in an eight-hour window and you fast the remaining 16 hours. For example, you finish dinner by 8pm and the first meal the next day is lunch at noon. Another popular program is the 5:2 plan in which one eats normally for five days per week but in the remaining two non-consecutive days, one takes in only 500 calories per day. Yet another program is referred as Eat-Stop-Eat where one finishes dinner one night and consumes nothing until dinner the next day, once or twice per week. Other programs include Alternate-Day fast (ie: fasting every other day) and the Warrior diet (one huge dinner every night, small snacks and vege during the day).
I think that the best plan for each individual is the one that you can easily fit into your life and that you can stick to it. The common denominator for all these plans is of course a significant duration of fasting in which the body sees no food and starts to burn the stored fat and glycogen due to a low level of insulin in our bloodstream. I have been trying intermittent fasting now for four months. For the first two months, I could go 14 hours without food. By 10:00AM, I was so ravenous that I got to have a snack. I did not feel any different and my weight stayed the same during those two months. However, I quickly realized that fasting was more a mental challenge than a physical contest of stomaching the hunger pangs. I let the pain sit with me and by sipping more water or coffee (milk free, by the way), the hunger pain just dissipates and I was able to extend my fasting phase to the full 16 hours. I shredded four pounds and half an inch off my waist, but I gained even more mental clarity and my subjective level of energy has also increased. The holiday season has reversed some of those gains but I am re-energized into this fasting schedule with my new love of the vegetarian diet.
The ocular benefits of intermittent fasting, however, are far more tenuous when compared to that of a plant-based diet. Most experimental studies that I reviewed which showed a promising effect were done in mice and the benefits may not be translatable to human subjects. They are nonetheless fascinating as intermittent fasting has been shown to reduce chronic low grade inflammation. Mice that were put on an intermittent fasting protocol (no food at night or fasting every other day) had a lower expression of inflammatory genes in the retina and prevented the development of diabetic retina changes. Similarly, it has also been shown that intermittent fasting in aged mice restores retinal ganglion cell resistance to intraocular pressure elevation. The ganglion cells make up the optic nerve and they expressed less markers of oxidative stress to eye pressure challenge in those mice that were on a diet. This may have implications to seniors with glaucoma in that intermittent fasting can help their optic nerves to withstand a higher pressure.
Finally, food restriction has been shown to restore the plasticity in the visual cortex of adult rats. After four weeks of every other day fasting schedule, the part of the brain that controls vision in adult rats began to behave like young ones, such that they were amenable to lazy eye treatment. Currently, lazy eye (amblyopia) treatment with patching or dilating eye drops to the fellow eye is generally effective only up to age nine. If undiagnosed amblyopia in human adults can be treated with the introduction of intermittent fasting, the impact to many patients with visual impairment due to amblyopia would be unimaginable.
2020 is the year of vision. I know what vision is in its physical sense but the best definition of vision that I know is by Jonathan Swift, the famed author of Gulliver’s Travel. Vision is the art of seeing what is invisible to others, said Swift. Whatever your 2020 resolutions might be, I hope they are beyond your wildest imaginations. And may you have the foresight and fortitude to carry you there.