DEAR DR. BLONZ: I am in my middle years, and my hair has become thin and is subject to frequent breakage. Someone suggested that I try some Norwegian kelp, as it was claimed to bolster the thyroid, which, if not functioning properly, will cause hair breakage and loss. Will this nutrient remedy my symptoms and stimulate hair growth? What other natural products would you suggest? -- S., Nashville

DEAR S.: Kelp is a seaweed known primarily for its iodine content, but it also contains small amounts of other minerals and vitamins. Iodine is an essential mineral that plays a role in manufacturing the thyroid hormones, which help regulate body metabolism.

Dry, coarse and breaking hair and hair loss can be symptoms of inadequate thyroid hormone -- hypothyroidism -- so perhaps that was the connection your friend was referencing. That is not the only possible explanation for your dry, thinning hair, and it is unclear whether kelp could be the answer if a lack of iodine is not the issue. Thyroid issues are diagnosed via blood tests.

Hair is among our most actively growing tissues. One's genetic background, certain health conditions, medications and aging can affect how your hair looks, grows and behaves. (For more information on the effects of aging on hair and nails, see b.link/ttn6tetr.)

The quality of your diet is also a factor. Aim for a good mix of fruits, greens and grains, which provide the essential vitamins and minerals. Include a regular intake of seafood, nuts and seeds, which are good sources of minerals and essential fatty acids.

We all need the essential nutrients -- deficiencies can negatively impact most of the body's systems, including the health of our hair -- after all, that's why they are called essential. However, it is unwise to suggest that consuming more than is required will make things better.

Be cautious with dietary supplements specifically promoted for hair health. Look for objective clinical evidence of a supplement's efficacy -- this is key, because you shouldn't rely on evidence only from the company profiting from the sale of the product.

Our hair is greatly influenced by the products and treatments we use on it. Also consider the exposure your hair receives to sunlight, chlorinated pool water, hats, helmets and body lotions. A knowledgeable esthetician or hair stylist can review your current practices and might be able to recommend products suited to your specific issues.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: I often see commercials for capsules of powdered greens and fruits and how they supply important nutrients and antioxidants, the same as eating whole fruits and vegetables. I have been taking this product daily for a few months and haven't noticed any effects. I want to know if these are a good replacement when I don't get enough fruits and vegetables in my diet. -- J.R., Oklahoma City

DEAR J.R.: I don't favor using supplements as a substitute for healthy eating. While these powdered products are made from dehydrated fruits and vegetables, there is no product standard, so you would have to check the ingredients list and label statements to see what's in each serving of a particular product. Some might be fortified with vitamins, minerals and phytochemicals, which must be listed on the ingredients statement. Outside of supporting testimonials, there tends to be little objective evidence available on these supplements. Look for studies that prove the products' efficacy.

Some supplements come in liquid form, some as tablets or capsules, and others come in powder form. They may have a grassy taste, but assuming you have no allergy or sensitivity issues -- which you should discuss with your health professional -- safety should not be a problem with products made according to the FDA's Current Good Manufacturing Practices (read more about these standards at b.link/uv7euav). However, relying on these supplements is not effective as a replacement for healthy eating. Taking care of yourself increases the odds that your body will be better able to fend off ill health and chronic ailments that are a part of the aging process.

To end this sermon, I suggest you reconsider your remedy for "not getting enough fruits and vegetables." The best thing to "take" is a plant-based, whole foods diet coupled with a healthy lifestyle. It's all a matter of priorities, and you will appreciate the payoff even more as you age. Healthful eating and an active lifestyle don't come with a guarantee, but they are the foundation of taking care of yourself.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: I received information from my doctor's office that read: "Don't take a multivitamin and mineral supplement containing iron. Men can't eliminate iron except through blood loss. High levels of iron in the body may promote cardiovascular disease/cancer." This information goes against the recommendation to take 8 mg of iron daily in my multivitamin. Please explain. -- R.A.

DEAR R.A.: Some context may help here. The human body has a daily requirement for iron, which it needs to make hemoglobin -- the oxygen-carrying compound in blood -- and myoglobin, a related compound that handles oxygen in the muscles. Both compounds are essential to producing energy for our cells. If the body has insufficient iron, the decreased hemoglobin and myoglobin levels can't produce needed energy.

The claim that men cannot eliminate iron is a bit confusing. The non-menstruating adult human body eliminates about 1 milligram of iron per day. Menstruating women lose significantly more. The daily iron requirement for premenopausal women (ages 18 to 50) is 18 mg. For adult men and postmenopausal women, the requirement is 8 mg a day. The dietary requirement is higher than the 1 milligram lost daily because we absorb only about 5% to 10% of the iron in our diet. Meat and poultry contain heme iron, which is the most efficiently absorbed form. (Read more on iron at b.link/z5msxnp.)

If you are an otherwise healthy individual with a healthful diet and lifestyle, you needn't fear taking a supplement that provides up to the recommended daily amount of iron, especially if the supplement is your primary source. There is no advantage, however -- and possible negative reaction -- in consuming excess iron. Discussing your multivitamin with a health professional familiar with your health issues is your best course of action.

Iron's darker side comes from epidemiological studies that found elevated iron stores associated with cardiovascular abnormalities and cancer. Consider how an iron nail will rust if left exposed to the elements, which is the result of iron's reaction with oxygen. Our bodies don't get rusty, per se, but it is thought that iron in our body grabs on to oxygen and then forces it on nearby substances, such as fats or cholesterol. (Oxidized fats and cholesterol are considered the primary villains of disease.) Antioxidants, including vitamins C, E and A, can help prevent errant oxidation and risk of disease.

Another element of iron's "Jekyll and Hyde" personality relates to individuals born with a genetic iron storage disease called hemochromatosis. Also referred to as "iron overload disorder," hemochromatosis is the inability to rid excess iron, which continues to build up, wreaking havoc on systems throughout the body.

Many people are unaware that they have this condition until symptoms emerge. Treatment often involves periodic removals of some of the patient's blood. Hemochromatosis is diagnosed via blood tests and genetic testing. (For more on hemochromatosis, see b.link/v9ndrk2.)

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.