Americans spend billions of dollars annually on dietary supplements. Yet, how much do they really help? More and more studies cite the benefits of this supplement or that, but it's often hard to evaluate a study's merit.
What we know for sure is that the best way to get most of the important nutrients we need is to eat a well-balanced diet that is low in saturated fats and includes whole grains, fresh fruits and vegetables. Supplements are additions to -- not a substitute for -- healthy eating. Before taking a supplement, consider eating foods that contain that particular nutrient. And it's always a good idea to discuss supplements with your doctor to ensure that they don't conflict with prescription medications or dietary restrictions.
Q: If I eat a lot of leafy greens, do I need to take lutein and zeaxanthin supplements?
A: Some published studies show that getting approximately 6 mg of lutein and zeaxanthin daily from foods decreases the risk of developing macular degeneration and cataracts. Lutein and zeaxanthin, which are carotenoids found in large amounts in the macula and peripheral retina of our eyes, function as antioxidants and also filter out blue light that might damage the eye. The best food sources for these carotenoids are dark, green leafy vegetables (kale, spinach), yellow and orange fruits and vegetables (squash, cantaloupes, peaches, sweet potatoes, carrots) and egg yolks. However, it may be difficult to reach the 6 mg target even with five daily servings of these foods. For people who have food restrictions, it is even harder. For example, people on blood-thinning medications may need to restrict their intake of leafy greens because they are rich in vitamin K, a nutrient that counteracts anti-coagulant medication. In addition, people with diverticulosis often have difficulty tolerating the high amounts of fiber in fruits and vegetables; and people who have diabetes need to be careful about natural sugars found in fruits.
For those who have age-related macular degeneration (AMD), daily amounts of 20 mg lutein and 6-10 mg zeaxanthin are generally recommended. The AREDS2 clinical trial underway (see page 3) is studying the effects of lutein and zeaxanthin supplementation.
Q: If I eat fish twice a week, should I still take a supplement that contains omega-3 fats?
A: Omega-3 fats are made up of the following fatty acids: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA is found primarily in plant foods, which our bodies convert to DHA and EPA. DHA and EPA are found mostly in fish. Scientists think that the omega-3 fat DHA, which is highly concentrated in the retina, may be protective of the eye. The best sources of DHA are cold-water fish such as wild Alaskan salmon, mackerel, herring and sardines, so eating these types of fish twice a week is definitely a good idea. However, if you're not eating fish that contain high sources of omega-3, you may want to supplement your intake with fish oil capsules. And if you don't enjoy fish, consider taking 1000-2000 mg capsules. If you're a vegetarian, look for foods or supplements with DHA from algal oil.
There is a cautionary note for people on blood thinning medications: check with your doctor because fish oil is a blood-thinner. The 2001 Age-Related Eye Disease Study (AREDS) found that people with AMD who ate fish at least twice a week had approximately a 50% reduction in the risk of advanced macular degeneration as compared to those who never ate fish. It's important to note that it has not yet been determined whether omega-3 is responsible for the difference. The AREDS2 study (below) is evaluating omega-3 supplementation.
Q: I have been reading articles about the need to increase vitamin D intake. Is supplementation necessary?
A: Researchers studying vitamin D are becoming concerned that people are not getting enough of this vital hormone that plays an important role in calcium absorption, bone growth and regulation of the immune and neuromuscular systems. Some good food sources include cod liver oil, salmon, mackerel, tuna, sardines, egg yolks, beef or calf liver, cheese and milk. In addition, there are now many brands of orange juice, yogurt and cereals that are fortified with D.
Many people don't know that there are two types of vitamin D: D2 (ergocalciferol) and D3 (cholecalciferol). D3 is the natural form that our bodies make from exposure to sunlight and is considered the supplement of choice. Many supplements contain vitamin D2 unless otherwise stated. Some experts recommend that people should get at least 1000 international units [IU] per day, which includes vitamin D from all sources -- food, vitamins and sunshine. Since absorption of vitamin D is affected by steroids, seizure drugs and other medications, any supplementation should be discussed with your doctor.
This article was written by Carol J. Sussman-Skalka, LMSW, MBA; with Eleanor E. Faye, MD, and Cydney H. Strand, RN